Natural killer and suppressor T-cell chronic lymphocytic leukemia.

A patient with low-grade lymphocytosis, splenomegaly, and neutropenia, but adequate myeloid leukogenesis, was found to have chronic lymphocytic leukemia, which represented a clonal proliferation of a distinct T-lymphocyte subset. The lymphocytes did not form E rosettes but had an OKT3+, OKT4+, OKT6+, OKT8+, OKT11+, HNK-1+, HNK-36+, OKIa1+, OKM1+ phenotype and functionally had suppressor and natural killer activity. Morphologically, they were large granular lymphocytes, which were strongly acid phosphatase positive and nonspecific esterase negative. They did not respond to mitogens, or to allogeneic cells. Initially, the spleen appeared to be the most involved organ and, judging from the high proportion of leukemic splenic lymphocytes in the S and G2/M phases of the cell cycle, was also the organ of origin of the leukemic cells. Only a few leukemic cells in the blood and bone marrow were in S and G2/M phases. After splenectomy, the lymphocyte count rose considerably and the bone marrow became progressively more infiltrated by tumor nodules. One year after diagnosis, the patient was started on chemotherapy because of progressive anemia. He responded to the chemotherapy by normalization of the hemoglobin and neutrophil count and had a moderate decrease in the bone marrow involvement and peripheral lymphocytosis.