Polyclonal hypergammaglobulinaemia in a case of B-cell chronic lymphocytic leukaemia: the result of IL-2 production by the proliferating monoclonal B cells?
SEQ DATA who developed polyclonal hypergammaglobulinaemia: 38.3 milligrams polyclonal IgG, 0.97 milligram IgA and 0.33 milligram IgM. Immunophenotyping showed a monoclonal lymphocytic population CD19+ CD5+ CD40+ CD23+, low sIg+ (95%), kappa type in the great majority (96%). RT-PCR of immunoglobulin genes gave evidence of monoclonal rearrangement of the IgM type. Our tests showed that IL-2 was produced when leukaemic B cells were stimulated with phorbol 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-promoter element. Finally, the amount of IL-2 secreted by these cells is about 39 ng/ml/10(6) cells, which is remarkably high for non-T cells. These 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 stimulated by IL-2 produced by proliferating monoclonal (leukaemic) B cells. Under cyclosporin A treatment, immunoglobulin secretion and B cell count remained low.
Mouzaki
A
A
Division of Haematology, Hôpital Cantonal Universitaire de Genève, Switzerland.
Matthes
T
T
Miescher
P A
PA
Beris
P
P
D000328:Adult; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology; D001483:Base Sequence; D002455:Cell Division; D005260:Female; D006801:Humans; D006942:Hypergammaglobulinemia / Q000209:etiology* / Q000276:immunology; D007376:Interleukin-2 / Q000096:biosynthesis*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000150:complications* / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D014407:Tumor Cells, Cultured
D007376:Interleukin-2