SUBSET DERIVATION OF T-CELL ACUTE LYMPHOBLASTIC LEUKEMIA IN MAN

Normal human peripheral blood T cells can be characterized as belonging to either the TH(+)(2) or TH(-)(2) T-cell subset. Approximately 20% of T cells are TH(+)(2), whereas 80% are TH(-)(2) utilizing specific heteroantisera. To determine whether human T-cell acute lymphoblastic leukemia (T-ALL) cells belong to one or another T-cell subset, cell surface phenotyping was performed on tumor populations from 25 patients with T-ALL. Tumor cells from these 25 individuals were either TH(+)(2) or TH(-)(2), but not both. 5 of 25 patients had TH(+)(2) T-ALL cells. These TH(+)(2) tumor populations were found exclusively in children and often without an accompanying thymic mass. TH(-)(2) T-ALL, in contrast, occurred in both children and adults and was almost always associated with thymic enlargement. Although children with TH(+)(2) T-ALL had as high or higher peripheral blast counts on presentation than their TH(-)(2) T-ALL counterparts, overall survival was greater for the TH(+)(2) group (>36 mo) than the TH(-)(2) group (<12 mo). These studies demonstrate that T-cell leukemias in man arise from distinct T-cell subsets and that cell surface characterization of T-cell malignancies may provide useful clinical data related to prognosis.