Selective reactivity of sera from alloimmunized sheep and cattle against human T and leukemia cells

Human B and T lymphocytes from a panel of healthy individuals were tested against serial dilutions of 68 mare, 81 cow, 7 sow, and 87 ewe sera. All the animals had been alloimmunized by pregnancies and/or blood transfusions. Weak correlations with HLA-A, B, C, and DR specificities were found in 20 sera. Twelve other sera, 9 from ewes and 3 from cows, had a strong reactivity against T lymphocytes but weak or no reactivity against B cells, spleen null cells, granulocytes, and platelets, suggesting a non-major histocompatibility complex (MHC) cross-reactivity. They were cytotoxic for most of the cells of malignant proliferative origin tested thus far, including T acute lymphoblastic leukemia (T ALL), common ALL (cALL), acute myeloblastic leukemia (AML), and Sezary cells, but were negative with B lymphoblastoid cell lines and cells from patients with B chronic lymphocytic leukemia (CLL) and chronic myelocytic leukemia (CML). The hypothesis that humans and certain other mammals share a common determinant on T-lineage cells and some malignant cells is advanced.