Variable regions of antibodies to synthetic polypeptides--I. Characterization of an idiotope expressed on antibodies and T-cell factors.

Spleen cells from a Lewis rat immunized with affinity-purified B10 anti-(T,G)-A-L antibody were fused with the non-secreting murine hybridoma SP2/0. Cell lines secreting monoclonal antibodies specific for mu- and kappa-chains, as well as an idiotope on anti-(T,G)-A-L antibodies, were isolated and characterized. The anti-mu and -kappa antibodies, are true anti-isotypes, reacting with sera from all strains of mice tested. The anti-idiotope antibodies recognize a determinant on antibodies binding a GT-containing epitope. The proportion of anti-GAT antibody bearing the idiotope varies markedly in different murine strains. A 1000-fold higher level of antibody from Igha mice than from Ighb and Ighe mice is required to give an equivalent inhibition of the idiotope-anti-idiotope reaction. Analysis of monoclonal antibodies expressing the idiotope indicates that the affinity of binding between idiotope and anti-idiotope can vary by as much as two orders of magnitude. Immunoadsorbants prepared with anti-idiotope antibody bind suppressor factor secreted by a GAT-specific T-cell hybridoma.