HLA class II restriction repertoire of antigen-specific T cells. II. Evidence for a new restriction determinant associated with DRw52 and LB-Q1.

We have studied the HLA class II restriction repertoire of antigen-specific T lymphoblasts (T-LB) in response to purified protein derivative (PPD) and tetanus toxoid (TET), presented by allogeneic antigen-presenting cells (APC). In 102 fully DR(1-w14) mismatched T-LB/APC combinations matching for DRw53 (MT3) had a significant influence on T-LB proliferation (p = 0.0005). Moreover, the supertypic specificity DRw52 (MT2) and LB-Q1 (a new class II determinant in strong linkage disequilibrium with DRw52) appeared to be markers for a new RD (p less than 0.0005). LB-Q1 was most strongly associated with this RD and among DRw52 identical T-LB/APC combinations additional LB-Q1 sharing significantly increased T-LB responsiveness (p = 0.02). DRw52- and LB-Q1-restricted responses could be inhibited by an anti-DRw52 and an anti-DR framework monoclonal antibody, indicating that DR(w52), LB-Q1, and the new RD are located at the same molecule.