A case of T-cell chronic lymphocytic leukemia with an unusual phenotype and central nervous system involvement

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Abstract
A case of T‐cell chronic lymphocytic leukemia is reported. The leukemic cells had the morphologic features of medium‐sized, mature‐looking lymphocytes, and had an affinity for the central nervous system. Cytochemically, they were positive for alpha‐naphthyl acetate esterase and acid phosphatase. They formed E‐rosettes (E+) and reacted with OKT11 but not with OKT3/Leu‐4, OKT4/Leu‐3, OKT8/Leu‐2, or OKM1, and did not possess IgG‐Fc receptors (FcγR). Functionally, they did not respond to phytohemagglutinin or concanavalin A, and were not natural killer cells or antibody‐dependent as well as alloantigen‐reactive killer cells. Furthermore, they did not possess a helper or suppressor T‐cell function for immunoglobulin synthesis. Results of immunologic studies suggest that the leukemic cells were derived from a normal counterpart of a lymphocyte subset present as a minor component of the peripheral blood, namely an E+, OKT3‐, OKM1‐, FcγR‐ subset, the function of which is not yet identified.