A case of T-cell chronic lymphocytic leukemia (T-CLL) expressing a peculiar phenotype (E+, OKM1+, Leu 1+, OKT3- and IgG EA-).

A case of chronic leukemia is reported. Malignant cells had the morphology of lymphocytes and an affinity for skin. Cytochemically, they were peroxidase negative, and NaF-resistant alpha-naphthyl esterase positive. The peripheral mononuclear cells formed E-rosettes and reacted with Leu 1 and OKM1. They were unreactive with OKT3, OKT4, OKT6, OKT8, and OKIa1. The cells did not possess surface IG, C3b receptors, or IgG Fc receptors (EAIgG). They responded weakly to phytohemagglutinin, and did not respond to concanavalin A. The cells did not adhere to Petri dishes or phagocytose latex beads. It is concluded that it was a case of OKT3-, OKM1+, EAIgG- T-cell chronic lymphocytic leukemia. This suggests that OKT3 does not recognize all peripheral T-cells, and that OKM1 is not specific for the monocyte-myeloid lineage. These cells may be useful in the characterization of E+, OKM1+ subset of peripheral mononuclear cells.