Human thymus/leukemia-associated antigen in normal and leukemic cells.

A saline extractable human thymus/leukemia-associated antigen (HThy-L) has been detected in immunodiffusion using rabbit antisera raised to human thymus extracts. HThy-L was demonstrated in extracts of normal thymocytes, lymphocytes from E-rosetting T-cell lines and from the blast cells of patients with E-rosetting acute lymphoblastic leukemia. Extracts of leukemic cells from patients with acute myeloblastic leukemia and E-rosette-negative acute lymphoblastic leukemia contained significantly lower quantities of HThy-L. Only trace amounts of the antigen were detected in normal spleen tonsil, peripheral blood, bone marrow and PHA-induced lymphoblasts. HThy-L appears to be an antigen associated with the intrathymic differentiation of human T cells and a marker of leukemic cells in certain forms of acute leukemia.