Generation in vitro of alloreactive lymphocytes is suppressed by the addition of spleen cells from mice infected with lymphocytic choriomeningitis virus.

The generation of cytotoxic T cells to alloantigens in mixed lymphocyte culture was suppressed by the addition of spleen cells from adult mice acutely infected with lymphocytic choriomeningitis virus. T cells of surface phenotype Lyt 1+2+ were required for the suppression. Suppressive cells appeared also in lymph nodes, but not in the thymus. In the spleen their number was maximal 6 to 8 days after infection. Infectious virus could not be detected in the suppressive spleen cells. Therefore the virus itself does not seem to cause the effect.