Interlaboratory study of the primary antibody response to sheep red blood cells in outbred rodents following exposure to cyclophosphamide or dexamethasone.

EPA guidelines provide a choice in evaluating humoral immune system function in rats and mice immunized with sheep red blood cells (sRBC): an antibody-forming cell (AFC) assay or a sRBC-specific serum IgM enzyme-linked immunosorbent assay (ELISA). Four different laboratories used both methods to detect suppression of the antibody response by cyclophosphamide (CP) or dexamethasone (DEX). Attempts were made to minimize interlaboratory variability through the use of common reagents and vendors; each laboratory used the same source for rodents, immunosuppressive agents, and one sheep for sRBCs, and determined optimal sRBC concentration for immunization and peak day of antibody response in female CD rats and CD1 mice. The CP dose at which statistical significance was first observed in each species was quite similar within each lab using either assay. For DEX, the AFC assay detected significant and greater suppression at lower concentrations compared to the ELISA in both rats and mice. All labs detected DEX suppression using an AFC assay, whereas only one lab detected significant suppression in both species using an ELISA. For both compounds the magnitude of suppression was greater using the AFC assay, and resulted in ID(50) values which were lower in the AFC assay when compared to the ELISA. In addition, cross-species comparisons of ID(50) values suggested rats were more sensitive than mice. These initial experiments with two chemicals indicated that the AFC assay is consistently better at identifying suppression of a T-dependent antibody response across laboratories following xenobiotic exposures in outbred rats and mice. Additional compounds will need to be evaluated before concluding that one method is superior or more sensitive to the other in detecting suppression of the antibody response.

Modulation of immune response following dietary genistein exposure in F0 and F1 generations of C57BL/6 mice: evidence of thymic regulation.

To further determine whether genistein (GEN) modulation of the immune responses was related to its endocrine-disrupting properties and time of exposure, pregnant C57BL/6 mice were exposed to GEN at 0-1250 ppm in feed starting on day 14 of gestation. The C57BL/6 offspring were exposed to GEN in utero and lactationally, and through feed after weaning until postnatal day 42. In dams, exposure to GEN increased the terminal body weight (250 and 1250 ppm), the number of splenic T cells and NK cells (250 ppm), and the activity of NK cells (250 ppm). In F(1) males, GEN increased the terminal body and spleen weights (25 and 250 ppm), the number of CD4(+)CD8(+) and CD4(-)CD8(+) thymocytes (25 ppm), and the number of splenic T cell subsets and NK cells (25 and 250 ppm). Moreover, splenic NK cell activity and anti-CD3-mediated splenocyte proliferation were increased in all treatment groups. In F(1) females, the percentages of CD4(-)CD8(+) and CD4(-)CD8(-) thymocytes (25 and 250 ppm), and CD4(+)CD8(-) and CD4(+)CD8(+) splenocytes (25 and 250 ppm) were increased. In contrast, the percentage and number of CD4(+)CD8(+) thymocytes were decreased (250 ppm). Exposure to GEN decreased the percentages of splenic NK cells in all treatment groups, and decreased the activity of splenic NK cells at the 25 ppm concentration. Additionally, evaluation of CD25(+) and CD44(+) expression by thymocytes indicated that the decrease in the percentage of CD44(+)CD25(+) thymocytes was at least partially responsible for the decrease in the percentage of CD4(-)CD8(-) thymocytes in F(1) male mice. Overall, the results demonstrate that GEN can modulate the immune system in both adult and developing C57BL/6 mice in a dose-specific manner. The gender-specific effects of GEN on the immune responses in F(1) mice suggest that GEN may modulate the immune system by functioning as either an estrogen agonist or antagonist. The differential effects of GEN on thymocytes in F(1) male and female mice indicate that GEN immunomodulation might be related to its effect on thymus.

Myelotoxicity in genistein-, nonylphenol-, methoxychlor-, vinclozolin- or ethinyl estradiol-exposed F1 generations of Sprague-Dawley rats following developmental and adult exposures.

The myelotoxicity of five endocrine active chemicals was evaluated in F1 generation of Sprague-Dawley rats following developmental and adult exposures at three concentration levels. Rats were exposed to genistein (GEN: 25, 250 and 1250 ppm), nonylphenol (NPH: 25, 500 and 2000 ppm), methoxychlor (MXC: 10, 100 and 1000 ppm), vinclozolin (VCZ: 10, 150 and 750 ppm) and ethinyl estradiol (EE2: 5, 25 and 200 ppb) gestationally and lactationally through dams from day 7 of gestation and through feed after weaning on postnatal day (PND) 22 to PND 64. The parameters examined included the number of recovered bone marrow cells, DNA synthesis, and colony forming units (CFU) in the presence of granulocyte macrophage-colony stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF) and erythropoietin. Except for the EE2, the concentrations of other individual chemicals in the diet were in an approximate range that allowed for a comparison to be made in terms of myelotoxic potency. Decreases in the DNA synthesis, CFU-GM and CFU-M seemed to be the common findings among the alterations induced by these compounds. Using the numbers of alterations induced by each chemical in the parameters examined as criteria for comparison, the order of myelotoxic potency in F(1) males was: GEN>MXC>NPH>VCZ; the order in females: GEN>NPH>VCZ. Additionally, some of the functional changes induced by these compounds were gender-specific or dimorphic. Overall, the results demonstrated that developmental and adult exposures of F1 rats to these endocrine active chemicals at the concentrations tested had varied degrees of myelotoxicity with GEN being the most potent. Furthermore, the sex-specific effects of these chemicals in F1 male and female rats suggest that there may be interactions between these compounds and sex hormone in modulating these responses.

Oral exposure to atrazine modulates cell-mediated immune function and decreases host resistance to the B16F10 tumor model in female B6C3F1 mice.

Atrazine (ATZ) is used throughout North America to control annual broadleaf weeds and grasses in various crops including; corn, sorghum, and sugar cane. Unfortunately, contamination of surface and ground water has occurred as a result of ATZ's chemical and physical properties, and its widespread use throughout the U.S. Midwest. A study of ATZ's immunomodulatory properties was conducted using female B6C3F1 mice and a panel of immune assays and host resistance models designed to evaluate cell-mediated and antibody-mediated immunity. Mice were administered ATZ by gavage (0, 24, 250, and 500 mg/kg/day) for 14 days then evaluated for immune responsiveness. ATZ treatment significantly increased the number of splenic CD8+ T cells, cytotoxic T cell and mixed leukocyte responses, and dose-dependently reduced host resistance to B16F10 melanoma. Thymus and spleen weights, total spleen cell numbers and fixed macrophage function was also reduced in mice that were exposed to ATZ. These results demonstrate that oral ATZ exposure is sufficient to alter cell-mediated immune function and disease resistance in female B6C3F1 mice.

Vinclozolin modulates splenic natural killer cell activity, antibody-forming cell response and phenotypic marker expression in sprague dawley rats: a two-generation feeding study.

The potential effects of the fungicide vinclozolin (VCZ) on the immune system were evaluated in F(0) (dams) and F(1) generations of Sprague Dawley rats exposed to a soy-free diet containing VCZ at 10, 150 and 750 ppm. In dams, exposure to VCZ at the highest concentration from gestation day 7 to postpartum day 51 (65 days total exposure) produced a significant increase in the numbers of splenocytes, B cells, T cells, helper T cells and cytotoxic T cells and a decrease in the percentage of NK cells. In F(1) males, exposure to VCZ gestationally, lactationally and through feed from postnatal day 22 to 64 (78 days total exposure) produced no effect on spleen or thymus weights or splenocyte subsets. However, increases in the spleen IgM antibody-forming cell response to sheep red blood cells (150 and 750 ppm) and the activity of NK cells (150 ppm) were observed. In F(1) females, exposure to VCZ produced a decrease in the activity of NK cells in all the treatment groups. Although decreases in the number of cytotoxic T cells (150 ppm) and the percentages of NK cells (10 ppm) and cytotoxic T cells (150 ppm) were also observed, the lack of a dose-related response suggested that these findings might not be biologically meaningful. In conclusion, these results demonstrate that exposure to VCZ at the concentrations tested modulates the immune responses in Sprague Dawley rats. Furthermore, the differential effect of VCZ in F(1) male and female rats is consistent with the reported anti-androgenic properties of VCZ.

Thalidomide modulation of the immune response in female B6C3F1 mice: a host resistance study.

Previously, we have reported that thalidomide (Thd) treatment can modulate the immune responses in female B6C3F1 mice. The present study was designed to evaluate whether or not these immunomodulatory responses were of sufficient magnitude to alter host resistances in a number of pathogen and tumor models. B6C3F1 mice were treated intraperitoneally with Thd (30-150 mg/kg) for 14 or 28 days, then inoculated with either Plasmodium yeolii, PYB6 fibrosarcoma tumor cells, B16F10 melanoma tumor cells, Listeria monocytogenes, or Streptococcus pneumoniae. Significant dose-dependent protection against B16F10 and L. monocytogenes was observed in mice that were treated with Thd. Furthermore, time course study using bacterial colony-forming units per spleen and liver as the endpoints indicated that the protective effect of Thd on host resistance to L. monocytogenes was time-dependent. In contrast, Thd treatment did not affect host resistance to P. yeolii, S. pneumoniae and PYB6 tumor. Additionally, the effect of Thd on the phagocytic function of the mononuclear phagocyte system (MPS) was evaluated following intravenous injection of 51Cr-labeled sRBCs. The overall phagocytic activity of MPS was not significantly altered by Thd treatment. In conclusion, these results demonstrate that Thd immunomodulation altered host resistance to B16F10 and L. monocytogenes; and selective modulation of Thd on the immune system may be responsible for the pathogen or tumor-specific effect of this compound.

Evaluation of the immunomodulatory effects of the disinfection by-product, sodium chlorite, in female B6C3F1 mice: a drinking water study.

Sodium chlorite is an inorganic by-product of chlorine dioxide formed during the chlorination of drinking water. Relatively little is known about the adverse health effects of exposure to sodium chlorite in drinking water. In this study, we evaluated sodium chlorite's immunomodulatory properties using female B6C3F1 mice and a panel of immune assays that were designed to evaluate potential changes in innate and acquired cellular and humoral immune responses. Female B6C3F1 mice were exposed to sodium chlorite in their drinking water (0, 0.1, 1, 5, 15, and 30 mg/L) for 28 days, and then evaluated for immunomodulation. Overall, minimal toxicological and immunological changes were observed after exposure to sodium chlorite. Increases in the percentages of blood reticulocytes, and the relative spleen weights were both observed at different sodium chlorite treatment levels; however, these increases were not dose-dependent. An increasing trend in the number of spleen antibody-forming cells was observed over the range of sodium chlorite concentrations. This increase was not, however, significant at any individual treatment level, and was not reflected by changes in serum IgM levels. A significant increase (26%) in the total number of splenic CD8+ cells was observed in mice treated with 30 mg/L of sodium chlorite, but not at the other concentrations. Splenic mixed leukocyte response and peritoneal macrophage activity were unaffected by sodium chlorite. Lastly, exposure to sodium chlorite did not affect natural killer cell activity, although a decrease in augmented natural killer cell activity (42%) was observed at the lowest sodium chlorite treatment level. These results suggest that sodium chlorite, within the range 0.1-30 mg/L, produces minimal immunotoxicity in mice.

Immunotoxicity of sodium bromate in female B6C3F1 mice: a 28-day drinking water study.

Bromate is one of the water disinfection by-products (DBPs) produced during the process of ozonation. The purpose of this study was to evaluate the immunotoxic potential of sodium bromate (SB) in female B6C3F1 mice. SB was administered in the drinking water for 28 days at doses of 80-800 mg/l. There was no difference in drinking water consumption between the animals exposed to SB and the tap water controls. Exposure to SB did not produce any signs of overt toxicity. Furthermore, no significant differences were observed in body weight, body weight gain, or the weights of thymus, liver, kidneys or lungs. No gross pathological lesions were observed in SB-treated animals. However, animals exposed to SB had a significant increase in absolute (28%) and relative (26%) spleen weights. The erythrocyte count, hemoglobin, hematocrit, mean corpuscular volume (MCV), platelet count, total leukocyte count, and counts of differential leukocytes were unaffected by SB. A dose-related increase in reticulocytes was observed following exposure to SB with the greatest increase (78%) observed at the highest dose level. Overall, there were no changes in the absolute number of total T cells, CD4+CD8- T cells, CD4-CD8+ T cells, natural killer (NK) cells and macrophages. Exposure to SB did not affect the percentage of B cells, although a slight increase in absolute number of B cells at the dose of 600 mg/l was observed. There was no alteration in IgM antibody-forming cell (AFC) response, mixed leukocyte reaction (MLR) and NK cell activity after exposure to SB. When the activity of peritoneal macrophages, unstimulated or stimulated with IFN-gamma and LPS, was evaluated using the cytotoxic/cytostatic assay of B16F10 tumor cells, the suppressive effect of macrophages on the proliferation of B16F10 tumor cells was decreased after exposure to SB. In conclusion, SB, when administered in the drinking water at doses from 80 mg/l to 800 mg/l, produced minimal toxicological and immunotoxic effects in female B6C3F1 mice.

Evaluation of the immunomodulatory effects of the macrolide antibiotic, clarithromycin, in female B6C3F1 mice: a 28-day oral gavage study.

The macrolide antibiotic, clarithromycin, is used extensively to treat bacterial infections associated with pneumonia, duodenal ulcers, and the advanced stages of human immunodeficiency viral (HIV) infection. In addition to its antimicrobial properties, several studies have indicated that clarithromycin also has anti-inflammatory and immunomodulatory properties. In this study, clarithromycin's immunomodulatory properties were evaluated using female B6C3F1 mice and a panel of immune assays that were designed to evaluate potential changes in innate, and acquired cellular and humoral immune responses. Female B6C3F1 mice were treated daily by gavage with clarithromycin (0, 125, 250, and 500 mg/kg) for 28 days then evaluated for immunomodulation. Minimal immunological changes were observed after 28 days of treatment. A slight increase in the number of spleen antibody-forming cells was observed at the 250 mg/kg treatment level, but not at other doses. Serum IgM levels were unaffected by the clarithromycin treatment. A significant increase in the number of splenic macrophages was also observed in mice treated with 125 mg/kg of clarithromycin, but this increase was not observed at the other treatment levels. Innate and cell-mediated immunity, as measured by natural killer cell activity, and mixed leukocyte and cytotoxic T cell response, respectively, were unchanged following treatment with clarithromycin. These results suggest that the immune system is not a target for clarithromycin at doses of 500 mg/kg or below.

Carbon tetrachloride is immunosuppressive and decreases host resistance to Listeria monocytogenes and Streptococcus pneumoniae in female B6C3F1 mice.

Carbon tetrachloride (CCl(4)) is an environmental contaminant that has been detected in ambient air, seawater, surface-water and snow. The immunotoxic potential of CCl(4) was evaluated in female B6C3F1 mice. The animals were administered with CCl(4) daily for 14 days at doses of 50, 100, 500 or 1000 mg/kg body weight by gavage with corn oil as a vehicle. Exposure to CCl(4) resulted in an increase of liver weight but not the body weight and the weights of brain, spleen, lungs, thymus and kidneys. Exposure to CCl(4) produced minimal effect on differential hematological parameters; however, it produced a significant increase in serum glutamic-pyruvic transaminase (SGPT) levels in all dose groups while other serum chemistries showed sporadic increases, primarily at the dose level of 1000 mg/kg. Exposure to CCl(4) produced a decreased humoral immune response; the IgM antibody forming cell (AFC) response to sheep red blood cells (sRBC) was suppressed with the maximal decrease (45%) observed at the dose level of 1000 mg/kg. The IgM serum titer to sRBC was also reduced with a maximal decrease (54%) observed at the dose level of 500 mg/kg. Although exposure to CCl(4) had no effects on the mixed leukocyte response (MLR), cytotoxic T lymphocyte activity and natural killer (NK) cell activity, a decrease in both the absolute number and the percentage of CD4(+)CD8(-) at the dose level of 500 mg/kg was observed. The functional activity of the mononuclear phagocyte system was compromised as reflected by a decrease in the vascular clearance of (51)Cr-sRBC and a decrease in the uptake of (51)Cr-sRBC by the liver. Finally, in the two host resistance models evaluated, exposure to CCl(4) decreased host resistance to both Streptococcus pneumoniae and Listeria monocytogenes with greater susceptibility to the latter. Overall, these studies demonstrate that CCl(4) was immunosuppressive in female B6C3F1 mice.

Glycidol modulation of the immune responses in female B6C3F1 mice.

The immunotoxic potential of glycidol was evaluated in female B6C3F1 mice using a battery of functional assays and three host resistance models. Glycidol was administered to the animals by oral gavage as a solution in sterile distilled water daily for 14 days at doses of 25, 125 and 250 mg/kg. In tier I, we observed that glycidol exposure produced a dose-related decrease in splenocyte IgM antibody-forming cell response to sheep red blood cells (sRBC); the spleen natural killer (NK) cell activity was also decreased. A decrease in B cell proliferative responses to anti-IgM F(ab')2 and/or interleukin-4 (IL-4) was observed while the splenocyte proliferative responses to T cell mitogen ConA and B cell mitogen LPS were not affected. The splenocyte proliferative response to allogeneic cells as evaluated in the mixed leukocyte reaction (MLR) to DBA/2 spleen cells was not affected. In tier II, we found that exposure to glycidol decreased the number and percentage of B cells and the absolute number of CD4+ T cells in the spleen while the number of total T cells, CD8+ T cells and CD4+CD8+ T cells was not affected. The cytotoxic T lymphocyte (CTL) response to mitomycin C-treated P815 mastocytoma was not affected; the cytotoxic activity of peritoneal macrophages was not suppressed. Moreover, the host resistance to Listeria monocytogenes was not affected although a slight increase in host resistance to Streptococcus pneumoniae was observed. However, exposure to glycidol decreased host resistance to the B16F10 melanoma tumor model with the maximal tumor formation in lung observed in the high dose group. Overall, these dada support the finding that glycidol is an immunosuppressive agent in female B6C3F1 mice.

Thalidomide stimulates splenic IgM antibody response and cytotoxic T lymphocyte activity and alters leukocyte subpopulation numbers in female B6C3F1 mice.

Thalidomide has been shown to have antiinflammatory and, more recently, immunomodulating properties, which are beneficial for the treatment of an ever-increasing list of immune related diseases. Although considerable knowledge regarding thalidomide s antiinflammatory properties has been acquired, relatively little is known about its immunomodulating properties in vivo. In this paper, a panel of immune assays was used to evaluate immunomodulation in female B6C3F1 mice treated intraperitoneally for 28 days with thalidomide (30, 100, or 150 mg/kg/day). Spleen antibody forming cell response was significantly enhanced by 37% in mice treated with 150 mg/kg/day, despite an 8% decrease in the percentage of Ig+ B cells. A significant stimulatory trend was observed for the cytotoxic T cell response across thalidomide treatment groups. An evaluation of the spleen leukocyte subpopulations revealed a 23% increase in the absolute number of CD8+ T cells in the 150 mg/kg treatment group and a 9 and 11% decrease in the absolute number of NK cells in both the 100 and 150 mg/kg thalidomide treatment groups, respectively. These findings demonstrate that, in addition to modulating spleen leukocyte numbers, thalidomide also stimulates murine humoral and cellular immune responses in vivo.

Immunological evaluation of the mycotoxin patulin in female B6C3F1 mice.

Patulin is a mycotoxin produced by many fungal species of the genera Penicillium, Aspergillus and Bryssochamys. Previous literature reports have suggested that patulin is toxic to the immune system. The studies presented were conducted to provide a comprehensive assessment of the effects of patulin on the immune system. Unlike previous reports, the doses of patulin used (0.08, 0.16, 0.32, 0.64, 1.28 and 2.56 mg/kg) were based on predicted human exposure levels. Female B6C3F1 mice were exposed orally to patulin for 28 days. Effects were not observed on final body weight or body weight gain. Relative weight of the liver, spleen, thymus, kidneys with adrenals, and lungs was not affected. Peripheral blood leucocyte and lymphocyte counts were decreased by approximately 30% in the two highest dose groups. The leucocyte differential was not altered. Total spleen cell, total T-cell (CD3+), helper T-cell (CD4+CD8-), B-cell (surface immunoglobulin+) and monocyte (MAC-3+) counts were not changed. Cytotoxic T-cell (CD8+CD4-) counts were increased 50% only by the highest dose. Natural killer cell (NK1.1+CD3-) and monocyte (MAC-1+) counts were increased 30% and 24%, respectively, only in the 0.08 mg/kg group. Humoral immune function as assessed by antibody-forming cell response and serum IgM titre to sheep erythrocytes, and cell-mediated immune function evaluated utilizing natural killer cell activity and the mixed lymphocyte reaction were not altered. Oral exposure to patulin for 28 days did not alter the ability of female B6C3F1 mice to mount either a cell-mediated or humoral immune response.

Immunotoxicity of 2',3'-dideoxyinosine in female B6C3F1 mice.

2',3'-dideoxyinosine (ddI) is one of several purine analogues used for the treatment of HIV and the acquired immunodeficiency syndrome (AIDS). These nucleoside analogues are promising in their inhibition of viral reverse transcriptase and termination of DNA synthesis. However, each of these drugs has toxicity associated with its use. A previous immunotoxicological evaluation of 2',3'-dideoxyadenosine (ddA), the parent compound of ddI, showed that ddA suppresses humoral immunity. These studies were undertaken to determine the potential for immunotoxicity due to treatment with ddI. This evaluation included an assessment of innate and acquired immunity after exposure to ddI (100, 250, 500, and 1000 mg/kg/day) for 14, 28 or 180 days. There were no overt signs of toxicity related to treatment with ddI except for a decrease in body weight in the group treated with the highest dose of ddI for 180 days. Overall, 6 months of treatment with ddI showed minimal effects on specific organs with the exception of the spleen and thymus. ddI selectively targets the immune system, with assays that challenge humoral immunity being more affected than those testing cell-mediated immunity. Innate immunity was unaffected by ddI treatment. Cell-mediated immunity, as measured by proliferative response to allogeneic cells (MLR) and the T cell mitogen (Concanavalin A), was moderately suppressed. There were no ddI associated effects on NK function or macrophage function as measured by the vascular clearance rate and phagocytic uptake of the tissue macrophages. The most sensitive indicator of ddI-induced immunotoxicity is suppression of the response to the T-dependent antigen, sheep red blood cells (sRBC). The No Observable Adverse Effect Level (NOAEL) for toxicity to the immune system following 14 days of exposure to ddI is 250 mg/kg. A suppression of the humoral immune response was seen at the lowest dose tested after treatment for 28 and 180 days. Thus, the NOAEL for both of these treatment periods is below 100 mg/kg/day.

The effect of methadone on the immune status of B6C3F1 mice.

Previously, morphine has been shown to elevate corticosterone via the hypothalamic-pituitary-adrenal axis and to suppress the immune system. The present investigation sought to determine if the mu-opiate receptor agonist methadone incurred a similar immune suppression in B6C3F1 mice. Serum methadone and corticosterone levels peaked 1 hr following a single subcutaneous injection of 20 mg/kg methadone HCl. Indeed, the rise in corticosterone levels paralleled that of methadone. After a single injection with 20 mg/kg methadone a pharmacokinetic analysis revealed a serum half-life of approximately 2 hr. Following five injections of methadone over a 24-hr period (every 6 hr), methadone levels were elevated as would be expected; however, corticosterone levels did not become elevated. This suggests that the ability of methadone to elevate corticosterone becomes uncoupled following repeated dosing, indicative of either a tolerance or an increased catabolic mechanism. Moreover, dosing every 6 hr for 5 days induced an increase in the catabolism of methadone itself. Therefore, all assays were begun 1 hr after subcutaneous administration of methadone HCl, a time at which both methadone and corticosterone serum levels were elevated. The primary IgM antibody response to sheep red blood cells (sRBC) was suppressed when splenocytes were immunized in vitro. In contrast, animals immunized with sRBC and assayed for the primary IgM antibody response 4 days later were not suppressed. The activity of the resident macrophages of the liver and spleen as measured by the uptake of 51Cr-sRBC was suppressed in a dose-dependent manner. Previously, it has been demonstrated that morphine suppresses hepatic and splenic phagocytic activity through an opiate receptor-mediated pathway that involves the release of corticosterone. It would appear that methadone plays a similar role in the suppression of hepatic and splenic phagocytosis.

Immunotoxicological profile of morphine sulfate in B6C3F1 female mice.

This study was undertaken to investigate a number of immune parameters which may be compromised with exposure to morphine sulfate. Mice were implanted subcutaneously with 8-, 25-, or 75-mg morphine sulfate pellets. Placebo pellets of identical makeup to the 75-mg morphine pellet (without morphine of course) were used as a control. Twenty-four hours after implantation of a 75-mg morphine pellet, blood levels reached a peak of 1610 ng/ml. Corticosterone increased in parallel with morphine and reached a peak level of 966 ng/ml 24 hr after implantation. The dose response of morphine to increase corticosterone, however, was flat. The weight of the lymphoid organs, spleen and thymus, and the liver were significantly reduced in the morphine-treated groups. Morphine treatment was associated with an increase in serum albumin, SGPT, BUN, and alkaline phosphatase indicative of hepatic damage. In contrast to increased serum proteins, the C3 component of complement was reduced in a dose-dependent manner. Leukocyte number in the peripheral blood was significantly reduced, while erythrocyte number and hematocrit were both increased. The number of B cells and T cells was decreased in morphine-treated animals. However, the percentage of T cells relative to B cells was increased. The primary IgM antibody response to the T-dependent antigen, sheep red blood cells, was decreased. Natural killer cell activity was reduced in response to morphine, as was the phagocytic capacity of Kupffer cells. Host-resistance models of Listeria monocytogenes or Streptococcus pneumoniae showed an increased resistance following administration of morphine. This increased host resistance, however, was not due to an increase in antimicrobial action of sera obtained from mice treated with morphine. The majority of morphine's effects on the immune system exhibited a flat dose response, suggesting that these effects may be mediated secondarily through corticosterone.

Subchronic 10 day immunotoxicity of polydimethylsiloxane (silicone) fluid, gel and elastomer and polyurethane disks in female B6C3F1 mice.

Millions of people have been exposed to silicones because of the widespread use in consumer products such as cosmetics and toiletries, food products, household products and paints. Silicones have wide use in medical practice, including lubricants in tubing and syringes, and as implantable devices. The most prevalent silicone in medical use is polydimethylsiloxane. This study was undertaken to determine the subchronic immunotoxicologic potential of the principal constituents of breast implants: silicone fluid, silicone gel and silicone elastomer. An alternative covering for devices containing silicone gels, polyurethane, was also included in the study. Silicone fluid and gel were injected subcutaneously into female B6C3F1 mice (1 ml/mouse) and 6 mm disks of silicone elastomer or polyurethane were implanted subcutaneously. There were no treatment-related deaths or overt signs of toxicity. None of the tested materials had notable effects on body or organ weights, erythrocytes or leukocytes in the blood, blood chemistries such as alanine aminotransferase, urea nitrogen, glucose, albumin or total protein. The cellularity of the bone marrow and responses to CSF-GM and CSF-M were normal. The tested silicones did not alter the distribution of B cells and T cells in the spleen, but polyurethane perturbed the distribution of CD4+CD8+ and CD4-CD8- T cells. The antibody response to sheep erythrocytes was not markedly altered, nor were proliferative responses to concanavalin A, phytohemagglutinin, lipopolysaccharide or allogeneic cells. Reticuloendothelial function was normal, but polyurethane evoked an enhanced phagocytosis of Covaspheres by adherent peritoneal cells. Natural killer cell activity and serum complement were not altered. All silicone materials afforded modest protection to a challenge with Listeria monocytogenes that killed 40 to 58% of control mice. Host resistance to Streptococcus pneumoniae or the B16F10 tumor was not affected by any of the treatments. There is a pattern indicative of some perturbation of T cell differentiation in mice implanted with a polyurethane disk.

Immunotoxicity of 180 day exposure to polydimethylsiloxane (silicone) fluid, gel and elastomer and polyurethane disks in female B6C3F1 mice.

Millions of people have been exposed to silicones which are present in consumer goods such as cosmetics and toiletries, processed foods and household products. In addition, silicones have been used extensively in medical practice as a lubricant in tubing and syringes, and as implantable devices. A silicone widely used in medical practice is polydimethylsiloxane. This study was undertaken to determine the immunotoxicologic potential of long term exposure to the principal constituents of breast implants: silicone fluid, silicone gel and silicone elastomer. An alternative covering for devices containing silicone gels, polyurethane, was also included in the study. Silicone fluid and gel were injected subcutaneously into female B6C3F1 mice (1 ml/mouse) and 6 mm disks of silicone elastomer or polyurethane were implanted subcutaneously. There were no treatment-related deaths or overt signs of toxicity during the 180 day exposure. None of the tested materials had notable effects on body or organ weights, erythrocytes or leukocytes in the blood, blood chemistries such as alanine aminotransferase, urea nitrogen, glucose, albumin or total protein, or serum CH 50 or C3 levels. The cellularity of the bone marrow and responses to CSF-GM and CSF-M were normal. The tested silicones and polyurethane marginally reduced the level of Ig+ cells in the spleen but did not consistently alter the distribution of T cell surface markers. The antibody response to sheep erythrocytes was not markedly altered, nor were proliferative responses to concanavalin A, phytohemagglutinin, lipopolysaccharide or allogeneic cells. Reticuloendothelial function was normal, as was phagocytosis of chicken erythrocytes and Covaspheres by adherent peritoneal cells. Natural killer cell activity was depressed in all silicone treatment groups and in mice implanted with polyurethane. No silicone or polyurethane treatment group displayed altered susceptibility to a challenge with Listeria monocytogenes, Streptococcus pneumoniae or the B16F10 tumor. The only consistent effect of 180 day exposure to silicone materials or polyurethane was a modest depression of natural killer cell activity.

Immunotoxicity of nitrobenzene in female B6C3F1 mice.

Nitrobenzene (NBZ) is primarily employed as an oxidizing agent in the synthesis of analine and benzene compounds. It produces myelotoxic effects and effects on erythrocytes in both animal models and man. Reported hepatosplenomegaly and effects on the bone marrow are indicators that NBZ may be immunotoxic. In these studies, female B6C3F1 mice were exposed to 30, 100 and 300 mg/kg of NBZ in corn oil by gavage for 14 consecutive days. To assess the immunotoxic potential of NBZ, body and organ weights were determined and selected immunologic and host resistance responses were studied. In these studies, the liver and spleen appeared to be the primary target organs. Both liver and spleen weights were dose dependently increased. Gross histopathologic examinations revealed significant changes in the spleen, consisting of severe congestion of the red pulp areas with erythrocytes and reticulocytes. Serum chemistry profiles showed increases in alanine aminotransferase and aspartate aminotransferase activities, indicating liver toxicity. Hematologic studies showed a decrease in erythrocyte number and a concomitant increase in mean corpuscular hemoglobin and mean corpuscular volume. A dose-dependent increase in peripheral reticulocytes was also seen. DNA synthesis was enhanced, as was the number of formed elements and the number of monocyte/granulocyte stem cells in the bone marrow of treated mice. IgM responses were decreased and the phagocytic activity of macrophages in the liver was dose dependently increased with a concomitant decrease in the activities in the spleen and lung. Other immunological parameters examined were unchanged. Host resistance to microbial or viral infection was not markedly altered by NBZ; however, there were trends towards increased susceptibility where T-cell function contributes to host defense. These data indicate that NBZ-induced hemolysis and liver injury are linked to the observed alterations in bone marrow activity.

Immunotoxicity of mono-nitrotoluenes in female B6C3F1 mice: I. Para-nitrotoluene.

para-Nitrotoluene (p-nitrotoluene) is used primarily as an intermediate in the production of various dyes, explosives, pharmaceuticals, and in the production of rubber and agricultural products. Previous investigations indicated that p-nitrotoluene was mutagenic in the Ames Test and that other mono-substituted nitrotoluenes bound covalently to hepatic macromolecules. The objective of these studies was to evaluate the potential immunotoxicity of p-nitrotoluene in mice exposed by the oral route. Mice exposed to p-nitrotoluene (200-600 mg/kg) daily for 14 days showed modest dose-dependent increases in liver and spleen weights. The livers of mice exposed subchronically to 400 and 600 mg/kg showed a mild to moderate swelling of the hepatocytes adjacent to the central veins; this swelling appeared to be reversible and there was no evidence of necrosis. The proportion of monocytes in blood was decreased in mice treated with p-nitrotoluene or toluene. Serum chemistries, bone marrow cellularity and the number of CFU-M and CFU-GM were unaffected. Immunologic investigations showed p-nitrotoluene suppressed the IgM response to sRBC and the DHR response to KLH. There was a 24% decrease in the percentage of CD4+ T lymphocytes in the spleen. There was no dose-dependent alteration of peritoneal macrophage numbers or differential count, unstimulated natural killer cell activity, response to B cell mitogen LPS, C3 activity or interferon levels. Exposure of mice to p-nitrotoluene decreased resistance to Listeria monocytogenes but not to Streptococcus pneumoniae, Plasmodium yoelii or the B16F10 melanoma, and increased resistance to the PYB6 tumor. These studies indicated that the immune system is an important target for toxicity of p-nitrotoluene. The decreased host resistance to L. monocytogenes can be attributed to the decrease in T lymphocytes and to a decreased delayed hypersensitivity response to KLH.