The immune response of the mouse to lymphocytic choriomeningitis virus. II. Active suppression of cell-mediated immunity by infection with high virus doses.

Infection of CBA/J mice with low doses of strain WE lymphocytic choriomeningitis (LCM) virus resulted in high cell-mediated and relatively low humoral virus-specific immune phenomena; anamnestic responses were marked. In contrast, infection with high doses of this virus induced no or low degrees of cell-mediated immune phenomena but higher antibody concentrations. Subsequent challenge of these mice did not reveal cell-mediated immunity. However, transfer of spleen cells from mice suppressed as to cell-mediated immunity together with virus into X-irradiated recipients led to marked anamnestic responses. Furthermore, when spleen cells from mice previously infected with low virus doses were injected into mice previously infected with high virus doses, cell-mediated immune phenomena could not be induced by concomitantly inoculated virus, although in controls anamnestic responses were readily evoked. Thus, infection with high doses of LCM virus actively suppressed LCM virus-specific cell-mediated immune responses but led to increased production of antibodies. suppressor cells could not be demonstrated.