POLYCLONAL HYPERGAMMAGLOBULINEMIA IN A CASE OF B-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA - THE RESULT OF IL-2 PRODUCTION BY THE PROLIFERATING MONOCLONAL B-CELLS

CLL is typically characterized by acquired hypogammaglobulinaemia. We report the case of a female patient suffering from B-CLL who developed polyclonal hypergammaglobulinaemia: 38.3 g/l polyclonal IgG, 0.97g/l IgA and 0.33g/l IgM. Immunophenotyping showed a monoclonal lymphocytic population CD19(+) CD5(+) CD40(+) CD23(+), low sIg(+) (95%), kappa ty pe in the great majority (96%). RT-PCR of immunoglobulin genes gave ev idence of monoclonal rearrangement of the IgM type. Our tests showed t hat IL-2 was produced when leukaemic B cells were stimulated with phor bol myristate acetate, ionomycin and lipopolysaccharide. In addition, transfections with the full IL-2 promoter or elements thereof revealed that IL-2 expression is inducible and mediated through the NF-kB-prom oter element. Finally, the amount of IL-2 secreted by these cells is a bout 39 ng/ml/10(6) cells, which is remarkably high for non-T cells. T hese results suggest that the large amounts of polyclonal IgG seen in this case of B-CLL are secreted by normal B cells which are in turn st imulated by IL-2 produced by proliferating monoclonal (leukaemic) B ce lls. Under cyclosporin A treatment, immunoglobulin secretion and B cel l count remained low.