Stimulation of humoral antibody formation by polyanions. III. Restoration of the immune response to sheep red blood cells by polyanions in thymectomized and lethally irradiated mice protected with bone marrow cells

Adult thymectomized C57BL/6J mice were lethally irradiated and injected 4 h later with 10 × 106 syngeneic bone marrow cells. Two weeks later animals were either inoculated with sheep red blood cells alone or treated with synthetic polyanions such as dextran sulfate or polyacrylic acid prior to inoculation with sheep red blood cells. On the fifth day after immunization the mice treated with polyanions showed a 19 S and 7 S plaque‐forming cell response as well as significant hemolytic titers. Control mice showed no significant plaque‐forming cell response or hemolytic titers. Polyanions seem to be capable of replacing thymus cell function.