Cytotoxins - cause of serum activity as complement in the lymphocytotoxic test.

The Ferrone's hypothesis elucidating the effect of rabbit complement in HLA typing using the cytotoxic test, due to the presence of xenocytotoxins to human lymphocytes in the rabbit serum was corroborated by the following experiments: 1. In human serum active as complement in HLA typing non-HLA lymphocytotoxins with optimum activity at 20 degree C were shown. In the guinea pig complement ineffective in HLA typing no cytotoxin to human lymphocytes were found. 2. In the rabbit complement cytotoxins to peripheral human lymphocytes were found when the incubation period of the cytotoxic test was prolonged to 3-4 h. 3. During the cytotoxic test on a model of rabbit immune sera - rabbit lymphocytes human complement showed a substantially higher activity than the rabbit complement. In the human complement xenocytotoxins to rabbit lymphocytes were demonstrated.