Characteristics of a poly(LTyr,LGlu)-poly(DLAla)--poly(LLys)-specific helper factor derived from a T cell hybridoma.

Abstract

AbstractA poly(LTyr,LGlu)‐poly(DLAla)‐poly(LLys) [(T,G)‐A‐L]‐specific helper T cell hybridoma, R‐9, was established by fusing activated T cells, enriched for specific helper activity by incubation on antigen‐pulsed splenic adherent cells, with the BW5147 thymoma line. Supernatants of this hybrid line or its active clones as well as ascitic fluids, aspirated from the peritoneum of mice injected with the hybridoma cells, manifest a(T,G)‐A‐L‐specific helper T cell‐replacing activity as assayed in an in vitro hapten‐carrier antibody production system. The factor activity can be specifically absorbed on and eluted from columns of immobilized (T,G)‐A–L, antibodies directed against the variable region of the immunoglobulin heavy chain and an antiserum directed against (T,G)‐A‐L‐specific idiotypes. Although the R‐9 factor and anti‐(T,G)‐A‐L antibodies share V region gene‐encoded determinants, they differ in their fine antigenic specificity, as determined by cross‐reactivity with closely related synthetic polypeptide immunogens. Whereas anti‐(T,G)‐A–L antibodies bind equally well to the L‐phenylalanine‐ or L‐histidine‐containing polypeptides (Phe,G)‐A‐L and (H,G)‐A‐L, to poly(LGlu)‐poly(DLAla)‐poly(LLys) (G‐A–L) and poly(Tyr,Glu)‐poly(LPro)‐poly(LLys) [(T,G)‐Pro–L], the R‐9 factor was completely absorbed on columns of (Phe,G)‐A‐L and G‐A‐L and only partially absorbed on immobilized (T,G)‐Pro–L and (H,G)‐A‐L. In addition to V region gene products, the R‐9 factor also bears major histocompatibility complex (MHC) determinants, which were found to map to the left end of the Ib region. Combination of inactive effluents obtained after absorption of the R‐9 factor on columns of anti‐H‐2b and anti‐Id antibodies resulted in active factor preparations, suggesting that although V region gene and MHC products are linked together in the active part of the factor, these moieties are located on different polypeptide chains which may associate in solution.