Mechanisms of regulation of cell-mediated immunity. IV. Azobenzenearsonate-specific suppressor factor(s) bear cross-reactive idiotypic determinants the expression of which is linked to the heavy-chain allotype linkage group of genes.

Abstract

T[thymus-derived]-cell derived suppressor factor(s) (SF) specific for azobenezenearsonate (ABA) were prepared by the mechanical disruption of suppressor cells. Such suppressor factors were adsorbed to and recovered from immunoadsorbents prepared from the F(ab'')2 fragments of rabbit immunoglobulin [Ig] directed against the cross-reactive idiotype of A/J anti-ABA antibodies. These ABA-suppressor factors were not retained on Sepharose 4B immunoadsorbent columns which had been coupled with F(ab'')2 fragments of normal rabbit Ig prepared from prebleeds of rabbits used to make anti-idiotypic antiserum. The specificity of the F(ab'')2 rabbit anti-idiotypic serum was established by direct idiotypic-binding assays and by affinity purification over an immunoadsorbent consisting of CRI[cross-reactive idiotype]+ anti-ABA Ig from A/J mice. ABA-suppressor factors were specifically absorbed and eluted from F(ab'')2 anti-idiotypic columns. The eluted suppressor factor can be specifically reabsorbed and recovered from a 2nd anti-idiotypic immunoadsorbent. The concordance between antigen-binding specificity and the presence of idiotypic determinants was demonstrated by adsorbing ABA SF to antigen columns and then fractionating the ABA-specific factor on anti-idiotypic immunoadsorbents. ABA-suppressor factors were specifically retained on immunoadsorbents directed against major histocompatibility complex (MHC) determinants. Factor eluted from anti-MHC columns could then be specifically adsorbed to anti-idiotypic immunoadsorbents. The same molecular complex that is recognized by the H-2 alloantiserum is apparently specifically adsorbed to an anti-idiotypic immunoadsorbent. Genetic analysis of the expression of CRI+ suppressor factor was performed using the C.AL-20 mouse strain which has the AL/N allotype and produces CRI+ anti-ABA Ig. The implication of these findings to the nature of T cell-derived regulatory molecules was discussed.