A COMPARATIVE STUDY OF HETEROLOGOUS ANTI‐MOUSE LYMPHOCYTE AND ANTIMOUSE THYMO‐CYTE SERA PREPARED BY TWO DIFFERENT IMMUNIZATION METHODS

Rabbit antimouse lymphocyte and antithymocyte sera were prepared with or without adjuvant. The sera were compared by their in vivo effect on allograft survival and their in vitro leukoagglutination and hemagglutination titers. Antilymphocyte serum made with adjuvant gave the best prolongation of skin survival of all sera tested, while antilymphocyte serum made without adjuvant gave the poorest survival. There was little difference in the effect on allograft survival between antithymocyte serum made with or without adjuvant. They both gave prolongation but to a lesser degree than antilymphocyte serum made with adjuvant. When a serum was toxic, the toxicity was caused by hemagglutinins and hemolysins and could be removed by absorption with red blood cells. The leukoagglutination titer of a serum was not always a reliable indicator of the effect of a serum on graft survival.