Antibody Response to Homografts

Antigenic differences between certain inbred strains of mice which could not be revealed by hemagglutination techniques were readily disclosed by lymphocyte cytotoxicity. With an improved cytotoxicity test lymphotoxic titers were as high as 1:512 with non-hemagglutinating A anti CBA antisera. In other mouse strain combinations, a close parallel of both types of antibody activity was obtained. Though both activities were absorbed from antisera proportionally by erythrocytes and lymph node cells, 100 to 1000 times as many erythrocytes as lymphocytes were necessary to produce an equivalent reduction in antibody activity. These findings suggest that erythrocytes may possess only subthreshold quantities of certain antigens which are present in readily detectable levels on lymphocytes. Lymphocyte cytotoxicity therefore may assay a wider range of allogenic antigens than hemagglutination.