IN-VIVO ACTIVATION OF T-CELL INDUCTION INTO THE PRIMED PHENOTYPE AND PROGRAMMED CELL-DEATH BY STAPHYLOCOCCAL-ENTEROTOXIN-B

The authors demonstrate that SEE immunization activates V beta 8(+) T cells and induces the acquisition of the primed phenotype as defined p reviously by low MEL-14 and high Pgp-1 expression. SEB-activated splee n CD4(+) and CD8V beta 8(+) T cells have different population dynamics and regulate the expression of MEL-14 and Pgp-1 differentially, sugge sting that the SEB-MHC class II complex preferentially activates CD4V beta 8+ T cells. Interestingly, at day 3 after SEB immunization, V bet a 8(+) T cells expressing low, but not high, levels of MEL-l4 undergo apoptosis, indicating that T-cell activation is a prerequisite for tri ggering programmed cell death. These results might help to trace antig en-reactive cells to the activated or primed pool, as well as to ident ify those cells which will undergo programmed cell death.