title: Human immune response to group A streptococcal carbohydrate (A-CHO). II. Antigen-independent stimulation of IgM anti-A-CHO production in purified B cells by a monoclonal anti-idiotopic antibody.
abstract: The paper describes the induction by a monoclonal anti-idiotopic antibody (anti-Id mAb) of specific antibody production to group A streptococcal carbohydrate (A-CHO) in purified human B cells of several unrelated individuals. The anti-Id mAb, designated 16F498 (anti-Id498), recognizes a recurrent idiotope (Id 498) associated with the combining site of human antibodies to N-acetyl-D-glucosamine (GlcNAc), the immunodominant group of A-CHO. Id498 is expressed on IgM anti-GlcNAc antibodies but does not occur on IgG antibodies with the same specificity. It occurs also on a minor population of IgM antibodies without specificity for A-CHO. Id498 was found in 19 of 27 sera from unselected healthy donors and thus seems to be frequently expressed within the adult B cell repertoire. The in vitro induction of anti-A-CHO antibodies was analyzed in human B cells extensively depleted for T cells. Specific antibody secretion required cross-linked anti-Id which was achieved by coupling the mAb to agarose beads. No antibody secretion could be induced by soluble anti-Id (1 and 10 micrograms/ml). An optimal response required soluble T cell-derived factors which were added as a mixture of recombinant interleukin 2 with a T cell hybridoma supernatant that augments B cell growth and differentiation. Under these conditions an antigen-independent specific increase of IgM anti-A-CHO production (2.6- to 10-fold, or up to 2000 ng/ml respectively) could be induced in blood B cell populations of four of six normal individuals expressing the Id498 at serum level.
mesh_terms: D000117:Acetylglucosamine / Q000276:immunology; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000276:immunology*; D000939:Epitopes; D006801:Humans; D007130:Immunoglobulin Idiotypes / Q000276:immunology*; D007132:Immunoglobulin Isotypes / Q000276:immunology; D007075:Immunoglobulin M / Q000096:biosynthesis; D066298:In Vitro Techniques; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013297:Streptococcus pyogenes / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000939:Epitopes; D007130:Immunoglobulin Idiotypes; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M; D011135:Polysaccharides, Bacterial; D000117:Acetylglucosamine