SUPPRESSIVE ANTIBODY IN HETEROLOGOUS ANTI-LYMPHOCYTIC SERUM ESTIMATED IN VITRO BY THE HEMOLYTIC ANTIBODY PLAQUE TEST

Abstract

Summary: Heterologous anti-lyniphocytic sera (ALS) produced by injection of rabbits with spleen cells from CBA or BALB/c mice were found to suppress hemolytic antibody plaque formation by antigenically stimulated spleen cells following prior incubation of such cells with ALS and complement. Cytotoxicity of such antisera for mouse spleen cells was also shown. Both antibody effects were demonstrable in high titer in both anti-CBA and anti-BALB ALS tested against cells of both strains. The bulk of the antibody was species-specific. However, the presence of significant amounts of strain-specific antibody was indicated, first, by higher titers in some classes of sera tested against cells of the immunizing strain than against those of the other strain; second, by absorption of the ALS with cell fragments of the other strain before testing against cells of the immunizing strain; and, third, by sequential absorption of ALS by cell fragments of the other strain and then those of the immunizing strain and elution of antibodies from these absorptions. Hemolytic antibodies appearing in such sera were more preponderantly species-specific. If strainspecific hemolysins were present, they could have constituted at most a substantially smaller fraction. The strain-specific component of an anti-CBA ALS was shown in vivo to cause prolonged retention of BALB skin grafts by CBA mice and reduction in the production of agglutinins to Sltigella by such mice