title: Biological effects of Pseudomonas aeruginosa exotoxin A: lymphoproliferation of T lymphocytes in athymic mice.
abstract: Pseudomonas aeruginosa exotoxin A has been observed to exert modulatory effects on the immune response. The present study examines the ability of exotoxin A to induce proliferation of splenocytes from athymic nu/nu mice. We observed that exotoxin A induced the proliferation of athymic nude splenocytes which could be abrogated by heating the toxin at 70 degrees C or by preincubation of the toxin with rabbit anti-exotoxin A antiserum. Photoaffinity-labelled toxin significantly induced splenocyte proliferation although the relative activity was reduced. Maximum nude splenocyte proliferation was observed at a toxin dose of 100 ng. This same dose was shown previously for athymic splenocytes to induce an enhanced response to the thymus-dependent (TD) antigen, sheep red blood cells (SRBC). The increased [3H]-TdR uptake in athymic splenocytes stimulated by exotoxin A was initiated by 24 hours and continued to day 10. Nude splenocytes depleted of Ig+ and Ia+ cells were induced to proliferate by exotoxin A. Cyclosporin A addition abrogated the ability of exotoxin A to induce proliferation. These results suggest that Pseudomonas aeruginosa exotoxin A can stimulate the proliferation of splenic T lymphocytes in athymic nu/nu mice.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000502:physiology; D003524:Cyclosporins / Q000494:pharmacology; D005098:Exotoxins / Q000493:pharmacokinetics / Q000494:pharmacology*; D006358:Hot Temperature; D007136:Immunoglobulins / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D008819:Mice, Nude; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D003524:Cyclosporins; D005098:Exotoxins; D007136:Immunoglobulins