Iron status alters murine systemic lupus erythematosus.

The effect of Fe status on murine systemic lupus erythematosus was investigated. Weanling female MRL/MPJ-lpr/lpr mice (systemic lupus erythematosus strain) were fed diets with the following levels (mg Fe/kg diet): 3 (severely deficient), 10 (moderately deficient), 35 (control) and 250 (supplemented). A fifth group was pair fed the control diet in the amounts consumed by the severely deficient group. C3H/Hej mice fed the same diets were used as non-lupus controls. Anemia was more severe in severely deficient mice than in all other MRL groups and C3H severely deficient mice. Incidence of skin lesions was highest in MRL severely and moderately deficient mice compared with pair-fed, control and supplemented mice. By 22 wk of age, mortality was higher in supplemented and severely deficient mice than in moderately deficient, pair-fed and control MRL mice. Anti-dsDNA activity in serum was not altered by Fe. In a second experiment, kidney function was examined in mice fed severely deficient, control, supplemented and pair-fed diets. Urine protein concentration was highest in supplemented mice at 14 wk of age. Serum urea nitrogen was significantly higher in MRL severely deficient mice than in pair-fed and control mice at 18 wk of age. Glomerular filtration rate, measured by creatinine clearance, was significantly lower in MRL severely deficient mice than in pair-fed and Fe supplemented mice at 16 wk of age and pair-fed and control mice at 18 wk of age. Renal histopathology was more severe in Fe supplemented mice than in pair-fed and control mice, and more severe in severely deficient and pair-fed mice than in control mice. Fluorescent staining of kidneys with anti-Ig G and anti-C3 fluorescein-conjugated antibodies was most intense in severely deficient mice, and the concentration of circulating immune complexes in serum was significantly higher in severely deficient mice than in all other groups. These data demonstrate that systemic lupus erythematosus in MRL/MPJ-lpr/lpr mice is altered by dietary iron.

Changes in plasma cytokines associated with peripheral nerve injury.

Plasma levels of interleukins 1, 2, 4 and 6 and tumor necrosis factor (TNF) were measured from 0 to 30 days in rats after a unilateral crush of the sciatic nerve at the level of the sciatic notch and after sham operations without nerve crush. Interleukin-6 was observed to peak and return to baseline levels within 24 h and remained at baseline for the duration of the experiment. An initial sharp rise in interleukin-1 and TNF was observed in all animals 1-2 days after the operation. A transient increase in interleukin-1 and TNF was also observed only in nerve-injured animals between 10 and 14 days after injury. A large increase in interleukin-2 appeared only in nerve-injured animals beginning at 11 days after injury and remained elevated for the remaining study period. No alterations in plasma interleukin-4 were observed at any time point. The experiments provide preliminary evidence for significant trauma-induced alterations in plasma cytokines which could provide a basis for some of the diffuse responses of peripheral neurons to trauma. The biphasic nature changes in plasma cytokines suggest that the immune system may participate in tissue reactions involved in the recovery from nerve injury.

Comparative toxicities of amphotericin B and its monomethyl ester derivative on glial cells in culture.

Amphotericin B (AmB) is a potent antifungal polyene macrolide antibiotic and is the drug of choice for the treatment of deep-seated mycotic infections. Its use is limited, owing to its nephrotoxicity, and it must be dispersed in deoxycholate for parenteral administration. In contrast, AME (the monomethyl derivative of AmB) is water dispersible, is appreciably less cytotoxic than AmB toward a variety of cell types, and is reportedly active against the acquired immunodeficiency syndrome virus (human immunodeficiency virus type 1). The latter activity has generated interest in AME as an antiviral drug. However, AME is perceived to be neurotoxic, based on the outcome of a human clinical trial of AME as an antifungal drug. AmB is not regarded as neurotoxic, presumably because any neurotoxicity in vivo is precluded by its nephrotoxicity. It was important, therefore, to determine the potential for neurotoxicity of the two agents in comparative tests, assessing the effects of their direct action against neural cells in culture. Rat cortical cells, comprising astrocytes and oligodendrocytes, were used. AME was at least 10 times less toxic than AmB and equally less toxic against several other nonneural cell types also included in these tests. Equally important, AmB disrupted the myelin sheath in these cultures, and it inhibited its generation. AME did not, even at a concentration 10 times greater than the toxic concentration of AmB. AmB is, therefore, potentially more neurotoxic than AME, contrary to current perception. AME is effective as an antifungal and antiviral drug at a concentration far below its toxic concentration for neural cells. Also, AME does not cross the blood-brain barrier appreciably, so that a therapeutic level in blood can be expected without encountering neurotoxicity.

The arachidonic acid cascade: an immunologically based review.

Certain polyunsaturated 20-carbon fatty acids can undergo oxidation to form prostaglandins (PGs), thromboxanes (TX), and leukotrienes (LTs). Various cells, including immunologic cells which constitute the immune system, are able to release these metabolites. Outlining the role that such eicosanoids play in the immune response will be the primary focus of this review.

Human splenic Fc receptor function and dysfunction: definition by circulatory clearance rate compared to computerized kinetic scintigraphy.

In vivo reticuloendothelial Fc receptor function was studied in 14 individuals. To assess this function Tc-99m-labeled IgG-coated autologous erythrocytes were injected intravenously and circulatory clearance rates of radioactivity were determined. In 12 individuals [6 normals and 6 patients with systemic lupus erythematosus (SLE)], kinetic computerized scintigraphic imaging of various internal organs was compared to circulatory clearance rates. Both circulatory clearance rates and percentage splenic uptake (PSU) were significantly depressed in patients. The difference between patients and normals was more significant for PSU than for circulatory clearance. Splenic uptake curves showed significantly less linearity for patients, suggesting that splenic defects in SLE are not only quantitative, but also are qualitative. Understanding the nature of immune clearance defects in immune complex mediated diseases may allow for a more rational approach to treatment of patients with these disorders.

In vivo reduction of circulating C1q binding immune complexes by intravenous gammaglobulin administration.

Six patients with systemic lupus erythematosus were treated with high-dose intravenous gammaglobulin. Immunological parameters were studied and included solid-phase immune complex determinations, quantitative immunoglobulins G, A, and M, as well as C3 and C4 concentrations. Pretreatment values of circulating immune complex concentrations as measured by either C1q binding or anti-C3 binding assays were elevated in all patients. Posttreatment values showed reductions in all C1q binding immune complexes (p less than 0.01) and anti-C3 binding immune complexes also decreased in 5 out of 6 patients. These assays are described in detail and were also used to define in vitro interactions between the intravenous gammaglobulin preparation and heat-aggregated IgG or sera containing elevated circulating immune complexes. No reduction of immune complex levels were observed when IgG was incubated in vitro with either heat-aggregated IgG or sera with elevated immune complex concentrations. The duration of the in vivo effect and the patients' clinical responses are described. These findings show that high-dose intravenous gammaglobulin administration can reduce certain types of immune complexes in patients with elevated levels of these substances.

Technicium as a radiolabel in the assessment of in vivo human Fc clearance.

99m-Tc was used as a radiolabel to study in vivo human clearance of IgG sensitized erythrocytes. Stannous chloride pretreatment at different doses and varying amounts of 99m-Tc were studied with respect to radiolabelling efficiency and elution. Mean in vivo clearance rates in systemic lupus erythematosus patients were significantly prolonged compared to controls. Using as little as 200 microCi of 99m-Tc per patient, in vivo human immune clearance can be determined with a minimal radiation biohazard. With this method, serial immune determinations can be performed within very short time frames, allowing for monitoring effects of immunomodulatory therapy as well as variations in disease activity.

Amplification by macrophages of prostaglandin-mediated immunosuppression in mice bearing syngeneic tumors.

The role of macrophages in tumor-mediated immunosuppression was examined, using C57B1/6 strain mice bearing four different immunosuppressive transplantable syngeneic tumors (Lewis Lung Carcinoma, B16 Melanoma, and two fibrosarcomas induced by methylcholanthrene in our laboratory). When tested for immunosuppressive activity, in inhibiting the induction of antibody formation by normal spleen cells in response to SRBC in vitro, the splenic and peritoneal macrophages from tumor-bearing mice were all significantly suppressive. The degree of suppression correlated with immunosuppression in tumor-bearing mice challenged in vivo with SRBC. Direct action of tumor cells on normal splenic macrophages in vitro caused them to become suppressive, the extent of suppression dependent on the time of interaction and on the immunosuppressive activity of the tumor cells in vivo. Pretreatment of suppressive splenic macrophages with indomethacin, a potent inhibitor of the synthesis of prostaglandins (PG), reduced significantly their immunosuppressive activity. Also, peritoneal macrophages from tumor-bearing mice produced significantly more PGE in culture than control macrophages. Thus, tumor-activated macrophages, presumably those macrophages that infiltrate the tumor in a host reaction against the tumor, serve to amplify the level of immunosuppression in the host by producing relatively large amounts of PGE that is a key physiological mediator in the activation and function of suppressor T lymphocytes. The stimulation of PGE synthesis in macrophages, as a result of their interaction with syngeneic tumors, is initiated by PGE produced in relatively large amount by the tumor cells.

A computer method for determining plaque size and plaque morphology.

We describe a computer method for determining plaque size and morphology from photographs of hemolytic plaques. The method eliminates any inter-measurer and intra-measurer inconsistencies that may arise when manual measurements are made on plaques whose boundaries are poorly defined. For circular plaques inner and outer plaque radii are determined. In addition the computer generates a density profile for each plaque, i.e., a plot of the film density versus the radial distance from the antibody forming cell. We demonstrate the use of the method by analyzing a time study of the growth of a single plaque.