Anti-class II antibodies potentiate IgG2a production by lipopolysaccharide-stimulated B lymphocytes treated with prostaglandin E2 and IFN-gamma.
IFN-gamma secretion by Th1 cells has been shown to preferentially promote the production of IgG2a in LPS-stimulated murine B lymphocytes. We recently reported that PGE2 potentiated the ability of IFN-gamma to augment IgG2a production in both Ag-specific and polyclonal systems via a cAMP-dependent pathway. Because antibodies (Ab) directed against class II MHC molecules have been shown to induce a rise in B cell cAMP, we hypothesized that this event, like PGE2 treatment, would promote the production of IgG2a. In this manuscript, cultures of small and large B cells treated with anti-Ia Ab are shown to produce significantly higher levels of IgG2a, compared with cultures treated only with IFN-gamma and LPS. Moreover, the combined treatment of B lymphocytes with IFN-gamma and PGE2 followed by anti-Ia and LPS resulted in a fourfold rise in IgG2a levels compared with IFN-gamma and LPS. Only anti-class II, but not anti-class I Ab, stimulated IgG2a production. Utilizing an ELISA spot assay, the frequency of IgG2a-secreting B cells was determined to be elevated fourfold in anti-Ia treated B cells. B cell cultures incubated with either PGE2 or anti-Ia exhibited elevated levels of cAMP and treatment with IFN-gamma primed these lymphocytes to the cAMP-elevating effects of either PGE2 or anti-Ia. Finally, RpcAMP, a cAMP antagonist that blocks cAMP from activating protein kinase A, prevented the increased production of IgG2a induced by anti-Ia Ab. These results support the theory that a cAMP pathway exists that promotes B cell IgG2a production. Within this pathway, IFN-gamma sensitizes B lymphocytes to cAMP elevators such as anti-class II Ab, and in conjunction with LPS, causes an increase in the frequency of IgG2a-secreting cells and the amount of IgG2a produced. These observations suggest that, after exposure to viral Ag in vivo, interaction between IFN-gamma-primed murine B cells and T cells will potentiate production of IgG2a, the predominant murine anti-viral Ig.
Stein
S H
SH
Department of Periodontics, Medical College of Georgia, Augusta 30912-1220.
Phipps
R P
RP
D000818:Animals; D000917:Antibody Formation / Q000187:drug effects*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology; D015232:Dinoprostone / Q000494:pharmacology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007074:Immunoglobulin G / Q000096:biosynthesis*; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000494:pharmacology*; D007518:Isoantibodies / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D011994:Recombinant Proteins; D015290:Second Messenger Systems; D015398:Signal Transduction
D000949:Histocompatibility Antigens Class II; D007074:Immunoglobulin G; D007518:Isoantibodies; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D007371:Interferon-gamma; D000242:Cyclic AMP; D015232:Dinoprostone