title: Immunoglobulin-specific T-B cell interaction. III. B cell activation by immunoglobulin-recognizing T cell clones.
abstract: Immunoglobulin (Ig)-specific T-B cell interactions were studied in the model of T cell recognition of Ig kappa chain Ig kappa-1b allotype in Ig kappa-1-congenic rats. Using Ig kappa-1b-recognizing major histocompatibility complex (MHC)-restricted T helper clones from August rats we have shown that Ig kappa-1b+ B cells from congenic August.1b rats presented Ig kappa-1b epitope of the processed self-synthesized Ig to T clones. This interaction was found to be a bidirectional regulatory event inducing specific MHC-dependent proliferation of both interacting T cell and B cell as well as Ig(Ig kappa-1b) synthesis. Small Ig kappa-1b+ B cells were capable of inducing T clone proliferation and becoming activated in response to the same T clone. Limiting dilution analysis suggested that every tenth cell in Ig kappa-1b+ B cell population is involved in this interaction. The bystander activation of Ig kappa-1a+ B cells by T clones in the presence of irradiated Ig kappa-1b+ spleen cells, if observed, was less than the level of specific Ig kappa-1b+ B cell proliferation. In contrast to a 20-fold increase of Ig(Ig kappa-1b) levels upon stimulation of Ig kappa-1b+/1a+ B cell population from heterozygous (August x August.1b)F1 rats by T clones, a "nonspecific" increase of Ig(Ig kappa-1a) was not observed. This result demonstrates the requirement for direct T-B contact for B cell activation to occur. The data suggest a great functional potency of T-B interactions mediated by T cell recognition of Ig-derived peptide/MHC class II complexes on the B cell surface. The implication of the data for idiotypic regulation enables us to propose the existence of putative idiopeptidic network T-B cell interactions.
authors.affiliation: Laboratory of Immunology, All-Union Research Institute for Genetics and Selection of Industrial Microorganisms, Moscow, USSR.
authors.forename: S M
authors.initials: SM
authors.lastname: Mazel
authors.forename: A Y
authors.initials: AY
authors.lastname: Rudensky
authors.forename: V L
authors.initials: VL
authors.lastname: Yurin
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002450:Cell Communication; D002999:Clone Cells; D007145:Immunoglobulin kappa-Chains / Q000096:biosynthesis / Q000276:immunology*; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D051381:Rats; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D007145:Immunoglobulin kappa-Chains