Abstract
Serum from a patient (CO) with acute lymphoblastic leukemia was reactive in immunoadherence assays with autologous leukemia cells but not with autologous blood lymphocytes or bone marrow cells during complete remission. Extensive absorption tests with an array of leukemia cells and normal cells were performed in order to define the specificity of the reaction. The autologous leukemia reactivity was either completely or partially absorbed with acute lymphoblastic leukemia cells obtained from 10 of 14 patients but not with acute nonlymphoblastic leukemia cells or normal hematopoietic cells. Some cultured lymphocytic leukemia lines also showed expression of the antigen. The absence of alloantibodies in CO's serum detectable in our assay allowed direct testing of CO's serum on allogeneic target cells. The results of these tests correlated with the results of absorption tests, indicating that small populations of antigen-positive cells were not missed with absorption tests. In addition, absorption tests with CO-positive allogeneic leukemia target cells showed the same pattern of antigen distribution as tests with autologous targets. CO reactivity was not removed by absorption with cell lines expressing human T-cell leukemia virus, nor did CO's serum react with adult T-cell leukemia cells from three patients.