Characterization of the fine specificity and antigen markers associated with the receptor of autoreactive T-cell hybridomas

In this study we attempted to define the determinants on Ia molecules recognized by autoreactive hybridomas obtained from (C57BL/6 × BALB/c) F₁ mice. The epitopes recognized by the T cells were characterized (a) using stimulating cells from various congenic and H-2 recombinant inbred strains and (b) by inhibition of activation with anti-Ia antibodies. Our hybridomas were strictly autoreactive and did not exhibit any alloreactivity, as is often observed for such cells. Our results show that more epitopes than previously believed are recognized by autoreactive T cells. One T-cell hybridoma (QW27.1) is unique in that it recognizes a hybrid F₁ Ia determinant. Antigenic markers associated with the receptor of the T-cell hybridomas were studied with monoclonal antibodies (mAbs) specific for L3T4 and a V_β "idiotype." The results indicate that all Lyt 1.2 autoreactive T cells express L3T4 antigen in association with their receptor. One clone (QW64.14) expresses the V_β idiotype recognized by F23.1 monoclonal antibody. Moreover, this clone is activated by F23.1, linked to Sepharose 4B beads, which was believed previously to activate only Lyt 2⁺, L3T4 T cells. The supernatant of one clone (QW17.5) helps B cells to differentiate into antibody-producing cells without requiring direct contact with the autoreactive clone.