Heterogeneity of CD7+ 4- 8- 1- leukemia: usefulness of cytoplasmic antigen detection for subclassification.

We identified CD3 and myeloperoxidase (MPO) antigens in the cytoplasm of leukemic cells from 15 patients with CD7+ 4- 8- 1- leukemia. Seven patients, five of whom had a mediastinal mass, had only cytoplasmic CD3 (cCD3) antigen; these seven were regarded as possibly being of T-lineage type. Six patients, one of whom had a mediastinal mass, showed both cCD3 and MPO; they were considered to have mixed lineage type. Two patients had neither cCD3 nor cytoplasmic myeloid antigens; they were therefore considered to have stem cell type. These two latter types were considered as the subgroups: mixed lineage or stem cell type. Patients with T-lineage type were good responders to L-17M therapy; four out of five who received L-17M therapy achieved complete remission. There were significant differences between the two subgroups in relapse-free survival, patients with T-lineage type exhibiting better prognosis than other types (p < 0.05).