Humoral aspects of the immune response to homografts. II. Relationship between the hemagglutinating and cytotoxic activities of certain isoimmune sera.

Isoimmune sera, prepared in BALB/c mice by immunization with living or lyophilized tissue from C57Bl/6 mice, were found to possess both hemagglutinating and cytotoxic activity for donor cells. Comparative titrations indicated a good correspondence between these two activities. Absorbtion with living or dead donor tissue caused removal or proportionate reduction of both activities. The results are consistent with the existence in isoimmune sera of a single class of isoantibodies, capable of agglutinating donor cells or of sensitizing them for complement lysis. Living and lyophilized tissue differ quantitatively, but not qualitatively, in their capacity to induce formation of these antibodies.