title: B-lymphocytes activation by the Fc region of IgG.
abstract: Strong stimulation of DNA synthesis (up to 150-fold) and blast transformation can be induced in mouse spleen cells by Fc fragments of human IgG. The mitogenic response is optimal on day 5 of culture and is dependent on the concentration of Fc fragments with a sedimentation rate of 3-5S. Intact IgG is also stimulatory, but only when modified by heat aggregation, and produces only a 10-fold increase in [3H]thymidine uptake. The stimulation by aggregated IgG is dependent on the Fc portion, since aggregated (or soluble) Fab or F(ab')2 fragments are inactive. The results show that the response is T-cell independent and that it is a function of nylon wool adherent, surface Ig-positive, Fc receptor-bearing B lymphocytes. Fc fragments do not induce plaque-forming cells to human IgG in normal mouse spleen cell cultures, but rather trigger polyclonal antibody synthesis (anti-goat erythrocytes, anti-2,4,6-trinitrophenyl). It is postulated that the Fc region of antibodies plays a role in the regulation of the humoral immune response by triggering clonal expansion of B lymphocytes.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000961:Antilymphocyte Serum / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology*; D002455:Cell Division / Q000187:drug effects; D003165:Complement System Proteins; D003208:Concanavalin A / Q000494:pharmacology; D004912:Erythrocytes / Q000276:immunology; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D009757:Nylons; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000276:immunology; D013936:Thymidine / Q000378:metabolism; D014301:Trinitrobenzenes / Q000276:immunology; D005719:gamma-Globulins
chemical_list: D000961:Antilymphocyte Serum; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D008070:Lipopolysaccharides; D009757:Nylons; D014301:Trinitrobenzenes; D005719:gamma-Globulins; D003208:Concanavalin A; D003165:Complement System Proteins; D013936:Thymidine