Immune processes in the course of infection with dysentery bacilli. III. Protective activity of spleen cells and serum from mice immunized with killed dysentery bacilli.

Killed dysentery bacilli induce immunity in mice which can be transferred to other mice with serum. Spleen cells do not transfer this immunity, in contrast to spleen cells from mice immunized with live dysentery bacilli. The results of this and previous studies 5,17 suggest that immunity in mice infected with dysentery bacilli depends on two coexisting effector mechanisms--cell-mediated and humoral immunity. Live bacilli induce both, however killed bacilli stimulated humoral immunity and protect mice equally effectively against lethal infection with dysentery bacilli.