Human cyclic neutropenia occurs in adults as well as children. Clinical illness is similar in the childhood and adult diseases, but distinctly different modes of onset suggest heterogeneity in its pathophysiology. We studied seven patients with cyclic neutropenia, three with disease acquired in adulthood, and four with the childhood-onset disorder. All three patients with adult-onset cyclic neutropenia had increased numbers of circulating large granular lymphocytes (LGL), whereas the four children with cyclic neutropenia had normal LGL counts. LGL from patients with adult-onset cyclic neutropenia expressed cell surface antigens HNK-1 (three of three patients) and IgG Fc receptors (two of three patients), although natural killer activity was low. Two of these patients were treated with alternate-day steroids, resulting in decreased LGL counts and abrogation of neutrophil cycling. We suggest that adult-onset cyclic neutropenia may be distinguished from the childhood-onset form of the disease by increased numbers of LGL. Furthermore, increased LGL may identify a subset of patients with cyclic neutropenia who respond to steroid therapy.
Large granular lymphocyte (LGL) leukemia is a rare disease characterized by clonal expansion of LGL associated with chronic neutropenia, multiple auto-antibodies, and occasionally polyarthritis. We studied cell surface antigen expression and functional activity of leukemic LGL from ten such patients. Using two-color flow cytometric analysis, we found that leukemic LGL from all ten patients expressed the CD3 and HNK-1 markers, while cells from only four patients expressed IgG Fc receptors (FcR). The LGL leukemic cells had little or no NK activity (defined as MHC-nonrestricted cytotoxicity against K562 target cells); however, NK activity could be induced in leukemic LGL by in vitro treatment with as little as 0.05 microgram/mL of anti-CD3 monoclonal antibody. Cell sorting experiments demonstrated that NK activity was induced in CD3+ leukemic LGL (either CD3+, HNK-1+ or CD3+, FcR+) with anti-CD3 monoclonal antibody but not in normal CD3+, FcR- T cells. Treatment with purified interleukin 2 (IL 2) also caused direct activation of some CD3+ leukemic LGL. Despite induction with anti-CD3 MAb or IL 2, activated leukemic LGL did not proliferate or express high density IL 2 receptors detectable by cell sorter analysis. Treatment with alpha interferon had minimal effect on NK activity of LGL leukemic cells. These results suggest that leukemic LGL may provide a useful model for examining the signals required for LGL maturation and activation.
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