title: Molecular basis of an isogeneic anti-idiotypic response.
abstract: The nucleotide sequences of the variable region genes expressed in the heavy and light chains of six isogeneic anti-idiotope antibodies recognizing idiotopes on two closely related antibodies with specificity for the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP) were determined. In two independently derived anti-idiotope cell lines the same or strongly homologous V kappa, VH and D region genes had originally been rearranged. The two lines express long and partly homologous N sequences (presumed to be not of germ line origin) at the border of D, resulting in CDR3s of unusual length. An unusually long CDR3, partly encoded by N sequences, is also present in the heavy chain of a third anti-idiotope antibody. The VH regions of the three remaining anti-idiotope antibodies originate from a single VH gene which belongs to the same VH group as the VH genes expressed in the other anti-idiotopes. Two of these antibodies, expressing similar V, D and J elements, had been isolated from the same mouse and appear to have diverged from the same B cell precursor by at least two rounds of somatic mutation. Somatic point mutations have occurred in most, if not all anti-idiotope V region sequences. In two instances somatic mutations in J increase the structural homology between anti-idiotopes. The anti-idiotypic response in this system is thus genetically restricted and may depend upon the selection of non-germ line sequences, suggesting an explanation for the low frequency at which anti-idiotope antibodies are expressed in this system.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000917:Antibody Formation; D001483:Base Sequence; D002460:Cell Line; D005796:Genes; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007130:Immunoglobulin Idiotypes / Q000235:genetics*; D007147:Immunoglobulin Light Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D051379:Mice; D008815:Mice, Inbred Strains; D011061:Poly A / Q000235:genetics; D012313:RNA / Q000235:genetics; D012333:RNA, Messenger; D013045:Species Specificity; D014158:Transcription, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D007143:Immunoglobulin Heavy Chains; D007130:Immunoglobulin Idiotypes; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA