STAPHYLOCOCCAL ENTEROTOXIN-B UP-REGULATES INTERLEUKIN-2 RECEPTOR BETA-CHAIN EXPRESSION ON TONSILLAR B-CELLS

The superantigen staphylococcal enterotoxin B (SEB) selectively up-reg ulates the interleukin-2 receptor (IL-2R) beta chain (p70) without up- regulating the IL-2R a chain (CD25) on a human tonsillar B cell popula tion depleted of T cells. This action of SEB, probably mediated by bin ding to major histocompatibility complex class II, renders B cells sen sitive to T cell-derived IL-2 and is sufficient for induction of vigor ous DNA synthesis with low concentrations of IL-2. This explains one o f the mechanisms by which bacterial superantigens activate large numbe rs of B cells and may reflect a similar mechanism operative in cognate helper T cell/B cell interactions.