Age-dependent changes in the response to staphylococcal enterotoxin B.

In the present study we investigated the response of old mice to staphylococcal enterotoxin B (SEB) immunization. Old mice were susceptible to lethal toxic shock, probably mediated by tumor necrosis factor-alpha, although lethal toxic shock was not observed in young mice. Old mice were able to produce more IL-2 and IL-4 than young mice in response to in vivo immunization with SEB. V beta 8+CD4+ T cells of old mice expanded less in vivo and were not deleted in response to SEB. However, in spite of the absence of clonal deletion, SEB was found to induce energy of SEB reactive cells in old mice, as demonstrated by reduced in vitro T cell proliferation to SEB and reduced in vitro IL-2 and IL-4 production.