Antibody-dependent cell-mediated antibacterial activity: K lymphocytes, monocytes, and granulocytes are effective against shigella.

Normal human peripheral blood lymphocytes, monocytes, and granulocytes decreased the viability of Shigella flexneri in vitro in cooperation with heat-inactivated rabbit hyperimmune anti-shigella antisera. Purified K and T lymphocyte populations used before the removal of Fc receptor-bearing cells were effective in this antibody-dependent complement-free system. In contrast, B lymphocytes and T lymphocytes from which Fc receptor-bearing cells were removed exhibited no activity. In the absence of antisera, lymphocytes and monocytes were ineffective whereas granulocytes were only moderately effective even when cells from patients recently infected with shigella were used. Convalescent (but not pre-infection) sera from these patients, however, induced marked cell-mediated antibacterial activity against their homologous infecting shigella whether the cells were from uninfected or infected individuals. These data suggest that Fc receptor-bearing lymphocytes, monocytes, and granulocytes play a role in host immune defense against enteric pathogens such as shigella even in locations where complement may be functionally deficient such as among secretory mucosal surfaces.