IN-VIVO APOPTOSIS IN SHIGELLA-FLEXNERI INFECTIONS

Shigella flexneri, an etiological agent of bacillary dysentery, causes apoptosis in vitro. Here we show that it also induces apoptosis in vi vo. We were able to quantify the number of apoptotic cells in rabbit P eyer's patches infected,vith S. flexneri by detecting cells with fragm ented DNA. Infection with virulent S. flexneri results in massive numb ers of apoptotic cells within the lymphoid follicles. In contrast, nei ther an avirulent strain nor an avirulent strain capable of colonizing Peyer's patches increases the background level of apoptotic cells. Ma crophages, T cells, and B cells are shown to undergo apoptosis in vivo . These results indicate that apoptosis may play a crucial role in the pathogenesis of shigellosis.