[Mitogenic effect of Legionella pneumophila: the ratio of proliferating T- and B-cells changes after immunization]

The splenic lymphocyte proliferative response of guinea-pigs immunized with L. pneumophila antigen (ALP) was studied. The immune animals were shown to express enhanced reactivity in response to E. coli lipopolysaccharide, as compared to the controls, while the response to concanavalin A was markedly decreased. After 3 days in the culture ALP induced a significant nonspecific lymphocyte transformation that was expressed to a similar degree in both experimental and control group. However, after a 5-day incubation ALP induced a specific proliferative response of the immunized guinea-pig splenocytes. The experiments on fractionation by passing through the column with nylon wool revealed that T cells are activated in non-immunized guinea-pigs. The results obtained prove that T cells mediate the immune response to ALP in guinea-pigs.