In Vitro Demonstration of Suppressive Antibody in Mouse Antisera vs. Allogeneic Spleen Cells

Abstract

Antisera produced by the injection of inbred mice with spleen cells of another inbred mouse strain were examined for cell-suppressive antibody against donor strain spleen cells by an in vitro test, using the hemolytic antibody plaque technique. Suppressive antibodies were detected by a reduction in plaque number, so that an endpoint of 50% plaque reduction could be determined for each serum. The plaque-reducing titers were found to be maximal in the 2nd or 3rd week after a second injection of allogeneic spleen cells. Some effects of dose and of time interval between injections were studied. In mice given an intraperitoneal irritant as well as being immunized with allogeneic spleen cells, plaque-reducing antibody was also found in ascitic fluids, at first considerably below the concentration in the serum but reaching approximately log₂=0.5 below the serum titer after the 10th day. The plaque-reducing effect of the antisera could be inhibited by prior incubation of the sera with antigens from cell fragments of donor-strain liver or spleen solubilized by triton and butanol. The specificity of both the plaque-reducing antisera and the inhibiting soluble cell-antigen was demonstrated.