title: Investigations into the mechanism of immunosuppression caused by acute treatment with O,O,S-trimethyl phosphorothioate: generation of suppressive macrophages from treated animals.
abstract: At concentrations normally found in the spleen, macrophages from animals treated with O,O,S-trimethyl phosphorothioate (OOS-TMP) for 24 hr were previously shown to be immunosuppressive (Rodgers et al., 1985b). In addition, it was shown that macrophages from OOS-TMP-treated animals had a diminished capacity to present antigen (Rodgers et al., 1985c). In this report, it was shown that lowering the number of splenic adherent cells (95% macrophages by morphology) utilized in cell-mixing experiments to reconstitute the nonadherent splenic populations returned the humoral immune response to control levels. One day following acute administration of OOS-TMP, resident peritoneal cells were able to suppress the proliferation of P815 tumor cells. In addition, proliferative responses to concanavalin A and lipopolysaccharide were decreased at suboptimal concentrations of mitogen. Fresh supernatants from splenocytes cultured for 24 hr from OOS-TMP-treated animals blocked the generation of a humoral immune response. However, supernatants from splenocytes of control animals generated in the same manner did not block the generation of a humoral immune response. These data suggest that OOS-TMP induced the generation of suppressive macrophages which may potentially act through the release of labile factors which block proliferation or antigen- or mitogen-induced lymphocyte stimulation.
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D002452:Cell Count / Q000187:drug effects; D002455:Cell Division; D005260:Female; D007166:Immunosuppressive Agents; D008213:Lymphocyte Activation / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D009374:Neoplasms, Experimental / Q000276:immunology / Q000473:pathology; D063086:Organothiophosphates / Q000494:pharmacology*; D009946:Organothiophosphorus Compounds / Q000494:pharmacology*; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects
chemical_list: D007166:Immunosuppressive Agents; D063086:Organothiophosphates; D009946:Organothiophosphorus Compounds; C019123:O,O,S-trimethyl phosphorothioate