Chronic T-cell lymphocytosis with neutropenia: report of a case studied with monoclonal antibody.

A 55-yr-old man presented with an 8-yr history of lymphocytosis. neutropenia. and infection. There was moderate splenomegaly without lymphadenopathy. and lymphocytosis of the blood (1 5.000-41 .200/cu mm) and bone marrow (30%): the latter also revealed no granulocytes more mature than the myelocyte. A diagnosis of leukemia could not be made from microscopic examination of the liver. spleen. or bone marrow. The circulating lymphocytes were T cells of the cytotoxic-suppressor subset with characteristic surface markers. They formed rosettes with unsensitized sheep erythrocytes (E rosettes), reacted with an antithymocyte heteroantiserum. were positive for the receptor for the Fc portion of lgG. and were devoid of surface immunoglobin. When examined with a panel of monoclonal antibodies. these cells reacted with 0KT3. a monoclonal that identifies peripheral T cells. OKT1 1. which identifies the sheep cell receptor. and 0KT5 and OKT8. which identify the cytotoxic suppressor subset of T