FAILURE OF B-CELLS OF CHRONIC LYMPHOCYTIC-LEUKEMIA IN PRESENTING SOLUBLE AND ALLOANTIGENS

B-cell-type chronic lymphocytic leukemia (B-CLL) patients have immunol ogical abnormalities of both B and T lymphocytes. Since T cell defects might depend upon a defective accessory function of neoplastic B lymp hocytes, we analyzed the ability of peripheral blood B cells of seven B-CLL patients to stimulate allogenic normal T cells in mixed lymphocy te reaction (MLR) and to present tetanus toxoid (TT) to autologous T c ells. In both systems, neoplastic B lymphocytes show a defective antig en-presenting function, which is more evident with disease progression . Such a defect cannot be ascribed to a decreased MHC class II molecul e expression nor to an abnormal IL-1 beta production, but it can be pa rtially accounted for by a low B7 expression. Pretreatment of neoplast ic B cells with interleukin-4 (IL-4) restores primary MLR, but has lit tle effect on the response to TT. The effect of IL-4 is not mediated b y quantitative modifications of class II and B7 molecule expression or of IL-1 beta production. (C) 1995 Academic Press, Inc.