Specificity of lymphocytotoxic anti-human antibodies in normal rabbit sera

Forty-nine of 127 normal sera from New Zealand white rabbits were found to contain cytotoxic antibodies against human lymphocytes. Reactions with these sera did not correlate with those of known HL–A or ABO specificities. However, four distinct specificities were found in 18 sera. These antibodies are labile upon prolonged storage at −20°C and heating at 56°C for 30 min and have low avidity. Since rabbit serum is the most efficient source of complement in the cytotoxic reaction with human lymphocytes, the quantity as well as the specificity of these natural antibodies in rabbit serum have to be considered when selecting this reagent for the lymphocytotoxic test.