title: Influence of the immunoglobulin heavy chain locus on expression of the VK1GAC light chain.
abstract: The VK1GAC light chain represents the dominant V kappa structure employed in the antibody response of A/J mice to streptococcal group A carbohydrate ( GAC ). Two anti-idiotypic antisera, anti- Id5 and anti- Id20 , with specificity for the VK1GAC light chain were used to examine anti- GAC antibody responses in a series of inbred mouse strains that differ at the heavy chain constant region ( IgCH ) allotype locus. Both idiotypes were expressed in normal and immune sera from mice of most IgCH allotypes, except IgCHb (C57BL/6J) and IgCHf (CE/J). C57BL/6J mice expressed Id5 , but not Id20 , whereas CE/J mice did not express either idiotype. Testing of recombinant inbred strains between BALB/c and C57BL/6 indicated that the pattern of idiotype expression did not correlate with IgCH allotype. The C X B recombinants expressed all three idiotype patterns that were observed in the panel of inbred strains. Testing of allotype congenic mice between BALB/c and C57BL/6 showed that CB.20 and BC.8 mice were Id20 -, whereas BAB-14 mice were Id20 +, indicating that both VH and background (V kappa or regulatory) loci must be derived from BALB/c to obtain Id20 expression. The difference in the frequency of idiotype expression observed between BALB/c and BAB-14 mice indicates that the IgCH locus may exert a quantitative influence on the expression of this light chain. To examine the Id20 -, Id5 + antibodies of C57BL/6 mice, anti- GAC hybridomas were prepared. Of 16 C57BL/6-derived anti- GAC monoclonal antibodies, six were reactive with anti- Id5 and not with anti- Id20 . Isoelectric focusing of the purified kappa light chains from three of these antibodies revealed two distinct spectrotypes that co-migrated with the two known VK1GAC spectrotypes observed with A/J anti- GAC light chains. Idiotypic analysis of in vitro recombinants between the heavy and light chains of A/J and C57BL/6 monoclonal antibodies demonstrated that the C57BL/6 light chains were idiotypically similar to A/J light chains when they were free in solution or paired with A/J heavy chains. These results demonstrate that C57BL/6 mice can express a light chain that is very similar, if not identical, to the VK1GAC light chain, although the light chain is expressed in lower frequency and is paired with a distinct VH structure, which can mask expression of one of the VK1GAC idiotypes. These effects on V kappa expression map to at least three genetic loci: VH, CH, and an unlinked locus.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D000911:Antibodies, Monoclonal / Q000032:analysis / Q000276:immunology; D008040:Genetic Linkage; D007126:Immunoglobulin Allotypes / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology*; D007130:Immunoglobulin Idiotypes / Q000235:genetics / Q000276:immunology; D007147:Immunoglobulin Light Chains / Q000032:analysis / Q000235:genetics / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology*; D007525:Isoelectric Focusing; D051379:Mice; D008805:Mice, Inbred A; D008806:Mice, Inbred AKR; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D011817:Rabbits; D011995:Recombination, Genetic
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D007126:Immunoglobulin Allotypes; D007143:Immunoglobulin Heavy Chains; D007130:Immunoglobulin Idiotypes; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D011135:Polysaccharides, Bacterial; C036112:streptococcal polysaccharide group A