T-cell dependent and T-cell independent immune response in normal and in with Litomosoides carinii infected cotton rats.

The immune responses to SRBC and LPS were examined in immunized and non-immunized inbred cotton rats at different times after an infection with Litomosoides carinii. During the infection, the T-cell dependent immune response to SRBC was significantly suppressed in non-immunized animals as compared to non infected controls. In contrast, after immunization with SRBC the antibody levels of infected animals were significantly higher in three of five events. At the onset of patency the response to SRBC was significantly depressed transiently in immunized animals. A corresponding depression could be provoked by injections of isolated microfilariae as well as by FCS in immunized animals, infected and non-infected. The level of the antibodies was dependent on the density of microfilariae in the peripheral blood. The T-cell independent response to LPS was equal in non-immunized infected animals as in controls. After immunization with LPS during prepatency and at onset of patency a distinct but commensurate reaction was observed. Only after immunization at the peak of patency, the immune response of infected animals was significantly suppressed. In general, the antibody levels to LPS were not influenced by the microfilaremia.