Staphylococcal enterotoxin B up-regulates interleukin-2 receptor beta chain expression on tonsillar B cells.

The superantigen staphylococcal enterotoxin B (SEB) selectively up-regulates the interleukin-2 receptor (IL-2R) beta chain (p70) without up-regulating the IL-2R alpha chain (CD25) on a human tonsillar B cell population depleted of T cells. This action of SEB, probably mediated by binding to major histocompatibility complex class II, renders B cells sensitive to T cell-derived IL-2 and is sufficient for induction of vigorous DNA synthesis with low concentrations of IL-2. This explains one of the mechanisms by which bacterial superantigens activate large numbers of B cells and may reflect a similar mechanism operative in cognate helper T cell/B cell interactions.