Virus Negative Sezary Leukemia, and Their Distinction Using Anti-Tac Monoclonal Antibody Identifying the Human Receptor for T Cell Growth Factor

As bstract. Adult T cell leukemia (ATL) and Se-zary leukemia are malignant proliferations ofT lympho-cytes that share similar cell morphology and clinical features. ATL is associated with HTLV (human T cell leukemia/lymphoma virus), a unique human type C ret-rovirus, whereas most patients with the Sezary syndrome do not have antibodies to this virus. Leukemic cells of both groups were ofthe T3, T4-positive, T8-negative phe-notype. Despite the similar phenotype, HTLV-negative S&ary leukemic cells frequently functioned as helper cells, whereas some HTLV-positive ATL and HTLV-positive Sezary cells appeared to function as suppressors of im-munoglobulin synthesis. One can distinguish the HTLV-positive from the HTLV-negative leukemias using a monoclonal antibody (anti-Tac) that appears to identify the human receptor for T cell growth factor (TCGF). Resting normal T cells and most HTLV-negative Sezary cells were Tac-negative, whereas all ATL cell populations were Tac-positive. The observation that ATL cells man-ifest TCGF receptors suggests the possibility that an ab-normality of the TCGF-TCGF receptor system may par-tially explain the uncontrolled growth of these cells. This article was presented in part at the meeting of The Association o