A common idiotype on SJL and C57BL/6 anti-(4-hydroxy-3-nitrophenyl) acetyl antibodies and its relationship with lambda chain production

Hybridoma cell lines secreting antibodies specific to (3-nitro-4-hydroxyphenyl) acetyl (NP) were generated by fusion of NP-immunized SJL spleen cells with the SP2/0 cell line. One hybridoma (N-hybridoma) anti-NP antibody (mu, lambda2) was found to partially inhibit (35-40%) the binding of the predominant idiotype in primary C57BL/6 anti-NP antibodies (NPb). Iodinated hybridoma antibody could be completely bound with anti-idiotypic antiserum made against either specifically purified C57BL/6 anti-NP antibodies, SJL anti-NP antibodies, or N-hybridoma antibody. The idiotypic specificities defined with anti-idiotypic antiserum made against N-hybridoma antibody were termed NP-1 idiotype. Strain distribution and genetic mapping studies indicate that the gene(s) controlling the production of NP-1 idiotype is closely associated with Igh-1b and Igh-1e alleles and mapped within the same chromosomal segment that controls the synthesis of NPb idiotype. However, unlike NPb idiotype, the expression of NP-1 idiotype is not influenced by the gene(s) that control lambda1 chain synthesis. Thus, SJL mice that produce low or undetectable levels of NPb idiotype due to a defect in lambda1 chain production express high levels of NP-1 idiotype. Specifically purified C57BL/6 and SJL anti-NP antibodies fully express NP-1 idiotype, the level of which correlates with the level of lambda2 chain-bearing molecules. Nonetheless, further experiments indicate that lambda1-bearing anti-NP antibodies can express extremely weak NP-1 idiotypic cross-reactivity.