Immunosuppression in vitro induced by leukemia virus-infected splenocytes (38544).

Immunization of dispersed spleen cells from normal mice in vitro with SRBC was suppressed by simultaneous incubation of the spleen cell cultures with splenocytes from mice previously infected with FLV. Cell-free virus preparations alone did not suppress the antibody response. In contrast, relatively small numbers of splenocytes from infected mice, even when present at a ratio of 1-500 normal spleen cells, significantly suppressed the in vitro immune response to SRBC. Viable leukemic splenocytes were necessary for immunosuppression although the leukemic cells did not have to be in direct contact with the normal spleen cells. Specific anti-FLV serum, when added to the leukemic splenocytes or to normal spleen cells separated from infected cells by cell-impermeable membranes, prevented immunodepression.