Suppression of cytolytic T-cell activity by staphylococcal enterotoxin B-induced suppressor cells: role of interleukin 2.
We have previously shown that staphylococcal enterotoxin B (SEB) is a potent inducer of suppressor T cells which function to inhibit antibody production in vitro. In the present paper we extend these studies and show that the SEB-induced suppressor cells also inhibit the development of cytotoxic lymphocytes in mixed-lymphocyte reaction (MLR) cultures. Since further analysis also showed that the level of interleukin 2 (IL-2) in cultures of SEB-primed cells was significantly reduced, experiments were carried out to determine the role of IL-2 in the inhibition of cytotoxic cell activity. Attempts to neutralize the suppression by supplementing MLR cocultures with delectinated supernatants from concanavalin A (Con A)-stimulated rat splenocytes were not successful. In addition, MLR cocultures supplemented on Day 0 with 50 units of affinity-purified IL-2 were also suppressed. Further analysis showed that the IL-2 activity in the supplemented MLR cocultures containing suppressor cells were significantly reduced by Day 3. However, repeated supplementation of the MLR cocultures with exogenous IL-2 was successful in achieving (and maintaining) "normal" levels of IL-2. The cytotoxic cell activity in these MLR cocultures remained suppressed. These results suggest that the inhibition of cytotoxic cell activity by SEB-induced suppressor cells is independent of IL-2 levels in the MLR coculture.
D000818:Animals; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004768:Enterotoxins / Q000494:pharmacology*; D007376:Interleukin-2 / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D008810:Mice, Inbred C57BL / Q000276:immunology; D051381:Rats; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology*
D004768:Enterotoxins; D007376:Interleukin-2; C031818:enterotoxin B, staphylococcal