IN-VIVO EFFECTS OF A BACTERIAL SUPERANTIGEN ON MACAQUE TCR REPERTOIRES

A macaque model was employed to explore staphylococcal enterotoxin B ( SEB) superantigen-driven T lymphocyte responses. The SEE-reactive V be ta(+) cell subpopulations demonstrated a striking tri-phase response i n rhesus monkeys following an SEE challenge in vivo. The hyperacute do wn-regulation, seen as early as 2 h through 2 days after SEE injection , was characterized by a disappearance of the reactive V beta-restrict ed PBL subpopulations from the circulation and decreased expression of these cell subpopulations in lymphoid tissues. Following this, a domi nant expansion of reactive V beta-expressing CD4(+) cell subpopulation s occurred in lymph nodes and spleens, whereas in the peripheral blood a preferential expansion of reactive V beta-expressing CD8(+) cell su bpopulations was seen. An exhaustion of this response was then seen, w ith a prolonged decrease in the number of the reactive V beta(+) CD4() lymphocyte subpopulations. Interestingly, monoclonal or oligoclonal dominance was seen in the reactive V beta(+) cell subpopulations in th e period of the transition from the polyclonal cellular expansion to t he exhaustion of the response, suggesting that some V beta(+) cell. cl ones may be more resistant than others to superantigen-mediated deplet ion. These results indicate that in vivo SEE superantigen-mediated eff ect on lymphocyte subpopulations in macaques is complex, suggesting th at profound dynamics in the TCR repertoires may in part account for th e susceptibility of higher primates to SEE-induced diseases.