Leu 11+ T gamma cell chronic lymphocytic leukemia with partially activated natural killer function and its further activation by recombinant IL2 in vitro.

A patient with T gamma cell chronic lymphocytic leukemia with the Leu 11+ phenotype and novel function of activated natural killer cells is reported. The peripheral blood mononuclear cells of this patient showed large granular lymphocytes by May-Giemsa staining and lamellipodia by scanning electron micrography. Tests on reactivity with monoclonal antibodies showed that most cells were Leu 11+, OKT3-/Leu 1-, OKT4-, OKT8-, Leu 7-, OKM1-, and Tac-. Freshly collected cells lysed not only K562, which is highly sensitive to natural killer cells, but also Raji cells and Daudi cells, which are not. Leu 11+ cells were triggered by recombinant interleukin 2 (rIL2) to proliferate, produce gamma-interferon (gamma IFN), and show enhanced HLA-DR antigen expression, and 30% of the Leu 11+ cells became positive for IL2 receptor antigen (Tac). The spectrum of cytotoxic activity of these cells against target cells was extended by rIL2; after treatment with rIL2, the cells also lysed HeLa cells and even fresh cancer cells. This stimulation also increased the activities of acid phosphatase and tartrate-resistant acid phosphatase of the cells and resulted in the appearance of nonspecific esterase activity. The expanded cell population may represent a neoplasm, but these findings provide information on a novel differentiation stage of activated NK cells.