Human B cell differentiation by Fc fragment. III. Effect of IL-1 and IL-2 on differentiation of human B lymphocytes induced by Fc fragments of human IgG.
The human Fc fragment of IgG, when added to blood mononuclear cells in vitro, induces B cell differentiation after 6 days of culture. This activity requires the presence of T cells and monocytes. This work explores the roles of interleukin 1 (IL-1) and interleukin 2 (IL-2) in B cell differentiation induced by Fc fragments. Peripheral blood mononuclear cells (PBMC) from normal donors were examined for plasma cell differentiation following stimulation with Fc fragment (15 and 30 micrograms/ml) with or without IL-1 (6 U/ml) or IL-2 (2 U/ml). Results indicate that both IL-1 and IL-2 accelerated B cell differentiation by the Fc fragment to 3 days of culture, compared to 6 days required with the Fc fragment alone. The time required for differentiation was not further shortened when both IL-1 and IL-2 were present in culture; both IL-1 and IL-2 were able to partially induce B differentiation alone at 6 days of culture. The importance of IL-2 in B cell differentiation was further supported by the finding that antibodies specific for the IL-2 receptor blocked B cell differentiation induced by Fc fragments, with or without additional IL-1 or IL-2. The depletion of monocytes also blocked B cell differentiation and the requirement for monocytes could not be replaced by exogenous IL-1; however, Fc fragments were shown to induce monocytes to secrete IL-1 beta after 24 hr in culture. These results suggest that accelerated differentiation of B cells into plasma cells requires a double signal provided by Fc fragments and IL-1 or IL-2. Monocytes are necessary for Fc fragment-induced differentiation and cannot be replaced by either IL-1 or IL-2.
Carosella
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ED
Institut Mérieux, Marcy l'Etoile, France.
Tilden
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AB
Dunlap
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NE
D000328:Adult; D001402:B-Lymphocytes / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000502:physiology*; D007074:Immunoglobulin G / Q000502:physiology*; D007372:Interferons / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology*; D007376:Interleukin-2 / Q000494:pharmacology*; D008875:Middle Aged; D009000:Monocytes / Q000502:physiology; D015375:Receptors, Interleukin-2 / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology
D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007375:Interleukin-1; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D007372:Interferons