QUANTITATION OF HUMAN THYMUS-LEUKEMIA-ASSOCIATED ANTIGEN IN ESTABLISHED HEMATOPOIETIC-CELL LINES BY RADIOIMMUNOASSAY

A competitive radioimmunoassay for a saline-soluble human thymus-leukemia-associated antigen (HThy-L) was applied for quantitation of this antigen in leukemia and normal hematopoietic cell lines. Highly Increased quantities of HThy-L were detected in all T-cell leukemia lines tested, regardless of the presence or absence of receptors for sheep erythrocytes. This elevated level of HThy-L in combination with high terminal de-oxynucleotidyl transferase and adenosine deaminase activities and the presence of a T-lymphocyte-specific surface antigen appear to represent stable phenotypic characteristics of T-cell lines. Most normal B-cell lines had low quantities of HThy-L. The level of HThy-L was slightly elevated in a considerable number of lymphoma B-cell lines and in all non-T, non-B leukemia cell lines tested. No relationship existed between quantities of HThy-L and an expression of different surface immunoglobulin isotypes In B-cell lines. Low quantities of HThy-L were detected in leukemia myeloid and myeloma cell lines as well as in B-cell leukemia lines originating from patients with B-cell acute lymphoblastic leukemia. Apparently, the Increased quantities of HThy-L in T- cell leukemia lines may be related to certain stages of T-cell differentiation at which leukemia cell transformation occurs. © 1979, Oxford University Press.