Detection and Characterization of Human Leukemia-Associated Antigens on Leukemic Cell Lines and Thymocytes

Abstract

Abstract The γG fractions of baboon and rabbit anti-MOLT-4 (a human leukemic T cell line) sera were extensively absorbed with glutaraldehyde-aggregated fetal calf serum and pools of normal human spleen cells and peripheral blood cells, both of which were derived from several different individuals. The spleen and peripheral blood cell preparations used contained normal T lymphocytes as well as B lymphocytes. The absorbed γG fractions were then further treated with several normal (nonmalignant) B cell lines that possessed HLA alloantigens known to be expressed on MOLT-4 cells. The resulting absorbed γG fractions of baboon (Abs-BαMOLT) and rabbit (Abs-RαMOLT) antisera were tested against thymocytes, leukemic T cell lines (MOLT-4, CCRF-CEM, CCRF-HSB-2, RPMI 8402) and a leukemic null cell line (NALM-1), various normal B cell lines, normal peripheral blood lymphocytes, normal spleen lymphocytes, and other control cells. Three different tests were used for both Abs-BαMOLT and Abs-RαMOLT: 1) A complement-dependent cytotoxicity test, 2) an 125I-antibody binding assay, and 3) a quantitative absorption-cytotoxicity test. Both the Abs-BαMOLT and Abs-RαMOLT that we used detected antigens common to the four leukemic T cell lines and to thymocytes and did not react with any of the control cells including normal T cells and cultured normal B cell lines. Abs-BαMOLT differed from Abs-RαMOLT in that only the former reacted with NALM-1, a leukemic null cell line, and only the latter reacted with an antigen(s) on MOLT-4 that was not detectable on thymocytes from certain donors. The Abs-RαMOLT was used for the isolation and partial characterization of the human thymus leukemia-associated antigens reported in the following paper.