Two patients with severe granulocytopenia and recurrent infections of the skin and oropharynx had excess T lymphocytes with receptors for the Fc portion of IgG (T gamma cells) in blood and bone marrow. The abnormal T gamma cells killed antibody-sensitized target cells in vitro (killer-cell activity) but did not suppress immunoglobulin production by B lymphocytes (suppressor-cell activity). T gamma lymphocytes from normal persons showed both killer-cell activity and suppressor-cell activity. In the serum of one patient, granulocyte antibodies, possibly of an autoimmune nature, were detected. The clinical picture in conjunction with the hematologic and immunologic findings characterized the disease of both patients as a distinct entity among the chronic lymphoproliferative diseases of T-cell origin.
Members of the Tumour Necrosis Factor-Receptor (TNFR) family play an essential role in the control of lymphoid cell growth and differentiation. The ligand of one of its lymphoid-specific members, CD27, was recently characterized as CD70, a type II transmembrane molecule with homology to TNF that is expressed on activated T and B cells. Ligation of CD27 by its natural ligand generates a potent costimulatory signal for cytokine production and proliferation of activated T cells. In contrast to normal B cells, where CD27 expression is confined to germinal centre cells and to a small subset of circulating B lymphocytes, CD27 expression is found on a large array of distinct B-cell neoplasia. Here, we review recent data on the expression and function of TNFR family members on normal and malignant lymphocytes and propose a role for CD27-CD70 interaction in B-cell development.
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