title: Responsiveness of chronic lymphocytic leukemia B cells activated via surface Igs or CD40 to B-cell tropic factors.
abstract: Recent studies performed in the laboratory have established that interleukin-4 (IL-4) used in combination with anti-CD40 monoclonal antibody (MoAb) 89 presented on Ltk- mouse fibroblasts stably expressing human Fc gamma RII/CDw32 (referred to as the CD40 system) sustains long-term proliferation of normal human B cells. In the present study, B-cell chronic lymphocytic leukemias (B-CLLs) activated through slgs or CD40 were examined for their capacity to proliferate and differentiate in response to various cytokines. Our results indicate that the outcome of IL-4 stimulation on the in vitro growth of B-CLL depends on the signalling pathway used for their activation. Whereas IL-4 did not display any growth-stimulatory effect on B-CLL activated by Ig cross-linking agents, it could stimulate DNA synthesis and enhance the viable cell recovery when leukemic B cells were cultured in the CD40 system. Most B-CLL samples were induced for IgM synthesis upon Staphylococcus aureus strain Cowan I stimulation. This Ig response was potentiated by IL-2 and antagonized by IL-4. Anti-CD40 MoAb used alone or in combination with cytokines (IL-1 alpha to IL-6, interferon gamma, tumor necrosis factor gamma, and transforming growth factor beta) failed to induce Ig secretion from B-CLL cells. No evidence for Ig isotype switching was obtained with the cytokines listed above, regardless of the mode of activation. Taken together, our results suggest that B-CLL cells can be partially released from their apparent maturation block by IL-2 and Ig cross-linking agents. In contrast, combinations of IL-4 and cross-linked anti-CD40 antibodies induced entry of B-CLL cell into cycle, but poorly stimulated their differentiation into Ig secreting cells.
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000032:analysis / Q000276:immunology*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D019013:CD40 Antigens; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D005260:Female; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D016130:Immunophenotyping; D007376:Interleukin-2 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology*; D007700:Kinetics; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000276:immunology* / Q000473:pathology; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D019013:CD40 Antigens; D016207:Cytokines; D006133:Growth Substances; D007376:Interleukin-2; D011947:Receptors, Antigen, B-Cell; D011994:Recombinant Proteins; D015847:Interleukin-4