title: Molecular analysis of heavy and light chains used by primary and secondary anti-(T,G)-A--L antibodies produced by normal and xid mice.
abstract: The primary (1 degree) antibody response to (T,G)-A--L shows limited heterogeneity, consisting mostly of side chain-specific antibodies that bind GT and that express the TGB5 idiotype (Id). The secondary (2 degrees) response is very diverse: antibodies that bind the backbone A--L constitute a third of the response, and a high proportion of the side chain-specific antibodies do not bind GT and are TGB5 Id-. To provide a molecular basis for understanding this difference in repertoire expression, we analyzed the Ig genes used by heavy and light chains of 1 degree and 2 degrees side chain-specific anti-(T,G)-A--L hybridoma antibodies (HP). Southern blot restriction analysis and nucleotide sequence analysis of the expressed genes used by three TGB5 Id+ 2 degrees HP showed usage of three different VH genes in two VH gene families (36-60 and J558), different D segments, and two different Vk1 genes (the Vk1A and Vk1C subgroups). Thus, antibody heterogeneity in the 2 degrees response is contributed by combinatorial diversity of distinct germ-line genes. Nucleotide sequence analysis of the expressed genes used by TGB5 Id+ 1 degree HP showed use of highly homologous VH genes in the J558 VH gene family and highly homologous Vk1A genes. The majority of TGB5 Id+ 1 degree HP from different donors gave similar heavy and similar light chain gene rearrangements by Southern blot restriction analysis, after correction for known or potential J region differences. The combined nucleotide sequence and Southern blot restriction analysis data suggest that most 1 degree B cells use the same or very similar VH and Vk genes, i.e., the 1 degree response is paucigenic. Different D segments were used by the TGB5 Id+ 1 degree and 2 degrees HP that were sequenced, and there was no apparent correlation between TGB5 idiotypy and VH, D gene, or JH gene usage. However, all TGB5 Id+ HP sequenced used highly homologous genes from the Vk1 group. Expression of a Vk1 light chain correlates with, but is not sufficient for, TGB5 idiotypy, because one GT-binding, TGB5 Id- HP was found to use a Vk1C subgroup light chain. By Southern blot and nucleotide sequence analysis, the Vk genes used by two TGB5 Id+ 2 degrees HP from xid mice are highly homologous, if not identical to the Vk1A gene(s) used by 1 degree and 2 degrees Id+ HP from wild-type mice.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology; D001483:Base Sequence; D005786:Gene Expression Regulation; D006825:Hybridomas / Q000502:physiology; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007130:Immunoglobulin Idiotypes / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007145:Immunoglobulin kappa-Chains / Q000235:genetics; D007153:Immunologic Deficiency Syndromes / Q000276:immunology*; D007156:Immunologic Memory; D051379:Mice; D005810:Multigene Family; D010455:Peptides / Q000276:immunology*
chemical_list: D007143:Immunoglobulin Heavy Chains; D007130:Immunoglobulin Idiotypes; D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains; D010455:Peptides; C021759:(T,G)-A-L