Development of a syncytia inhibition assay for the detection of antibodies to bovine leukemia virus in naturally infected cattle; comparison with Western blot and agar gel immunodiffusion.

A syncytia inhibition assay (SIA) for the detection of antibodies to bovine leukemia virus is described. This test involves specific antibody-mediated inhibition of BLV-induced cytopathic effects in an indicator cell line. A total of 300 sera were screened commercially by agar gel immunodiffusion (AGID) and were then screened by Western blot and SIA. The new assay system provided results which were comparable to Western blot and AGID. The results obtained suggest that SIA may be more sensitive than either of the other two assay systems examined for the determination of the infection status of cattle.

Spontaneously generated non-Hodgkin's lymphoma in twenty-seven simian T-cell leukemia virus type 1 antibody-positive baboons (Papio species).

Simian T-cell leukemia virus type 1 (STLV-1), a type C retrovirus associated with leukemia/lymphoma in Old World monkeys, is closely related to human T-cell leukemia virus type 1, the etiologic agent of adult T-cell leukemia/lymphoma in humans. In a colony of 3200 baboons, the prevalence of antibodies to STLV-1 is more than 40%. Seropositivity is more frequent in female baboons than in males and increases with age. Of 27 STLV-1 antibody-positive baboons with non-Hodgkin's lymphoma, 20 were females and 7 were males, ranging in age from 3 to 21 years (mean, 13 years). Non-Hodgkin's lymphoma was not found in STLV-1 antibody-negative baboons. Clinical signs and laboratory findings were variable but generally included lethargy, low body weights, anemia, dyspnea, lymphadenopathy, hepatosplenomegaly, pneumonia, nodular skin lesions, and leukemia with or without multilobulated lymphocytes in peripheral blood. Radiography revealed pulmonary infiltrates consistent with pneumonia in 17 of the baboons. Serum chemical values were normal except for hypercalcemia in one baboon. Lymphocytosis was found in 18 of the baboons, with leukemia diagnosed in 11. At necropsy, variable enlargement of lymph nodes and other lymphopoietic tissue was usually found. Pale tan to white space-occupying foci typical of proliferative lymphoid tissue were often found in various organs, including lungs, spleens, livers, skin, and hearts. The lungs in 14 baboons had thickened pleuras, congestion,edema, and large tan to brown areas of consolidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Simian T-cell leukemia virus type I infection in captive baboons.

Human T-cell leukemia virus type (HTLV-I) is a type C retrovirus that has been linked to both adult T-cell leukemia and neurological disorders in humans. Baboons and other Old World non-human primates harbor a related virus termed simian T-cell leukemia virus type 1 (STLV-I), which may also be associated with neoplastic disease. To explore the utility of the baboon as a model for HTLV-I infection and disease, 329 baboons from a colony of 3200 at the Southwest Foundation for Biomedical Research (SFBR) were analyzed for the presence of antibodies against STLV-I. An overall seroprevalence rate of > 40% was found, with higher rates in females versus males. Furthermore, seroprevalence rates increased dramatically with age, reaching greater than 80% in animals over the age of 16. Molecular and antigenic analysis of proviral DNA isolated from both tumor tissue and a cell line isolated from a baboon with non-Hodgkin's lymphoma (NHL) indicates that STLV-I in this colony is closely related to HTLV-I. Furthermore, monoclonally integrated provirus isolated from lymphoma tissue was detected, strongly implicating STLV-I in the etiology of this malignancy. DNA primer pairs homologous to HTLV-I sequences amplified both HTLV-I and STLV-I, but not HTLV-II, providing further evidence for a close genetic relationship between baboon-derived STLV-I and HTLV-I. The detailed study of a large population of naturally infected baboons may therefore shed some light into the complex processes required for the induction of disease associated with HTLV-I infection in humans.

Induction of interferon synthesis and cytotoxicity by murine peritoneal macrophages exposed to glycoprotein ligands.

Thioglycollate-induced murine C57BL/6 and C3H/HeN peritoneal macrophages synthesized interferon-beta (IFN-beta) in response to exposure to glycoproteins such as horseradish peroxidase (HRP) or mannosyl or fucosyl bovine serum albumin (BSAman of BSAfuc, respectively), but not glucosylated or galactosylated BSA (BSAglu or BSAgal, respectively). These results suggest participation of the mannosyl-fucosyl receptor (MFR) in this response. IFN synthesis was augmented by culturing macrophages in L cell-conditioned medium prior to exposure to these substances. Macrophages obtained from lipopolysaccharide (LPS)-resistant C3H/HeJ mice did not produce IFN in response to HRP. Furthermore, IFN-induction by HRP was blocked by polymyxin B. In addition, exposure of macrophages to HRP or BSAman induced cytotoxicity against NIH 3T12 cells. Cytotoxicity was not inhibited by the presence of anti-IFN-alpha/beta. In contrast to IFN induction, however, macrophages activation was LPS-independent, since this activity was demonstrated in macrophages from C3H/Hej mice. The carbohydrate specificity of these responses suggests that the MFR or an another scavenger receptor may be involved in the responses to these substances, and that cytotoxicity and IFN-induction by glycoproteins follow unique pathways.

Serologic confirmation of simian T-lymphotropic virus type I infection by using immunoassays developed for human T-lymphotropic virus antibody detection.

Serum specimens from diverse species of Old World monkeys, categorized as seropositive (n = 97) or seronegative (n = 23) for human T-lymphotropic virus (HTLV) infection, were tested by using recombinant env-spiked Western immunoblot assays and synthetic peptide assays for simultaneous detection and discrimination of simian T-lymphotropic virus (STLV) infection. Of the 97 seropositive specimens, 93 reacted with the recombinant transmembrane (r21env) protein and 90 reacted with a recombinant, MTA-1, derived from the central region of the external glycoprotein of HTLV-I (rgp46env), thus yielding test sensitivities of 96 and 93%, respectively. While 1 of the 23 negative monkey specimens reacted with r21env, none reacted with rgp46env, for overall specificities of 96 and 100%, respectively. Analysis of synthetic peptide-based immunoassays demonstrated that while 85 of 97 (88%) seropositive specimens reacted with HTLV-I-specific epitope (p19gag), none of the specimens reacted with HTLV-II-specific epitope (gp52env). These results show that recombinant envelope-spiked Western blots provide a simple means for serologic confirmation of STLV-I infection and that type-specific synthetic peptides can be used to confirm the virus type in seropositive monkey specimens.

Peroxidases enhance macrophage-mediated cytotoxicity via induction of tumor necrosis factor.

Tumor necrosis factor (TNF) is a monokine which is involved in macrophage-mediated cytotoxicity (MMC). We have previously reported that peroxidases can activate thioglycollate-induced macrophages to the tumoricidal state in vitro. The present study was undertaken in an attempt to correlate peroxidase-induced MMC with production of TNF. Horseradish peroxidase (HRP) was used as the principal model for these studies. Resident and thioglycollate-induced macrophages exposed to peroxidases were examined for both MMC against 3T12 cells and production of TNF. Thioglycollate-induced macrophages exposed to HRP, bovine lactoperoxidase, or human myeloperoxidase demonstrated enhanced secretion of TNF. When exposed to HRP, both resident and thioglycollate-induced macrophages secreted significant amounts of TNF and acquired the ability to lyse 3T12 cells. However, resident macrophages were considerably less efficient in both their cytotoxic activity and TNF secretion. Macrophage-mediated cytotoxicity was eliminated by the addition of specific antisera to TNF. In addition, replacement of culture supernatants within 24 hr after exposure of the macrophages to HRP increased tumor cell killing in the absence of additional detectable TNF production, suggesting that other factors may be involved in peroxidase-induced MMC. These results indicate that TNF is intimately associated with peroxidase-induced MMC and suggest a possible role for peroxidases as immunomodulators via augmentation of macrophage capacities and functions.

The differential effects of calcium starvation on Duchenne muscular dystrophy fibroblasts.

The effects of nutrient deprivation on normal and Duchenne muscular dystrophy fibroblasts were examined. The requirements for Ca2+ and fetal bovine serum were assessed by their effects on the cells' ability to support viral replication, and by ability of the cells to divide in the presence of low levels of these nutrients. When grown in Ca2+-deficient media, Duchenne fibroblasts supported viral replication at a rate 2- to 2.5-fold greater than did normal fibroblasts. At normal Ca2+ levels, Duchenne fibroblasts supported viral replication at levels slightly lower than their normal counterparts. After 48 hr in medium containing 0.2 mM Ca2+, the growth of normal cells was arrested, while Duchenne fibroblasts were relatively unaffected. When grown in medium containing either 0.2 or 2.0% serum, the growth of normal cells was arrested within 48 hr, with cell death occurring within 72 hr. Duchenne fibroblasts continued to divide at these serum levels for 72 hr, reaching higher cell densities than normal cells. These results suggest that a defect related to Ca2+ metabolism may be part of the Duchenne phenotype, which could be used to identify Duchenne muscular dystrophy cells.

Peroxidase-induced enhancement of chemiluminescence by murine peritoneal macrophages.

A number of substances have been shown to enhance the respiratory burst (RB) of macrophages. Many of these substances are not normally found in vivo. The present study suggests that a group of enzymes characterized as peroxidases have the ability to significantly enhance the RB and concomitant phagocytosis by murine peritoneal macrophages. Horseradish peroxidase (HRP), lactoperoxidase (LPO), and microperoxidase (MPO) can significantly augment these functions. Both resident and thioglycollate-induced macrophages exhibited enhanced chemiluminescence (CL) upon exposure to HRP, however, the effect was more pronounced with the latter. The increase in CL was correlated with an increase in production of superoxide, which was measured by reduction of cytochrome c. Horseradish peroxidase immobilized on an inert carrier, was capable of enhancing the RB suggesting that it does not have to enter the cell in order to function. Hemin, hematoheme and hematoporphyrin had little effect on macrophage stimulated CL. All of the peroxidases tested caused increased phagocytosis of opsonized zymosan. These studies indicate that peroxidases are capable of stimulating the RB, phagocytosis and possibly other macrophage functions.

Survial from acute renal failure with and without multiple organ dysfunction.

A 10-year retrospective analysis has been carried out of 114 patients dialysed for acute renal failure. Fifty-eight patients, predominantly suffering from multiple organ failure, required treatment in an Intensive Therapy Unit (ITU); 56 less severely ill patients were treated in a Renal Unit. Overall survival in the former group was 36% and in the latter group 63%. In the first 5 years of the study, survival in the ITU patients was 31% and in the second 5 years, was 38% in spite of a trend towards increased severity of illness. These results challenge the view that haemodialysis is rarely worth-while in patients with multiple organ failure, and suggest that current management techniques have improved prognosis. The most important adverse factors continue to be old age, sepsis and gastrointestinal disease.

Treatment of accidental hypothermia: a prospective clinical study.

A 15-year prospective study was carried out of 44 patients with accidental hypothermia (mean age 60 years) admitted to an intensive therapy unit. The lowest core temperature recorded in each patient ranged from 20.0 to 34.3 degrees C. The precipitating factors were poisoning (by drugs, alcohol, or coal gas) in 25 cases and various illnesses in 19. Rewarming was achieved in 42 patients by applying a radiant heat cradle over the torso, and in two patients by mediastinal irrigation with warmed fluids. Twelve patients died, but only two during the period of rewarming. Thus rewarming may be consistently and safely achieved irrespective of the cause of hypothermia, and normal body temperature may be regained as rapidly as is compatible with adequate tissue perfusion and oxygenation. Surface rewarming of the torso is perhaps the simplest technique available, but internal rewarming procedures may be desirable or essential in the presence of, for example, profound hypothermia, severe hypotension, or ventricular fibrillation. Mortality was attributable to underlying factors or disease and not to hypothermia.