Analysis of the fine antigenic specificity of the (T,G)-A--L specific helper T cell continuous line E-9M(+)

The TCGF-dependent E-9M(+) T cell continuous line was derived from in vitro activated T cells to (T,G)-A--L, which were further enriched for specific helper activity by incubation on antigen-pulsed splenic adherent cells. Cells and supernatants of this continuous line manifest a (T,G)-A--L specific helper activity, as assayed in an in vitro hapten-carrier antibody production system. The fine antigenic specificity of the helper effect induced by the E-9M(+) line was studied using 2 experimental approaches: A) NIP-OVA primed spleen cells were cultured with T cells of the line or its derived factor and challenged with NIP conjugated to different polypeptide antigens related to (T,G)-A--L. B) Supernatants of the E-9M(+) line were passed through immunoabsorbents built of the different synthetic polypeptide antigens, and the residual (T,G)-A--L specific helper activity was tested in the effluents and eluates recovered from the columns. Identical cross-reaction patterns were observed using both experimental systems. With the random synthetic polypeptides it was found that cells of the (T,G)-A--L specific E-9M(+) line or their derived factor completely cross-react with (Phe,G)-A--L and G-A--L and only partially cross-react with (H,G)-A--L, whereas no cross-reaction was observed with (T,G)-Pro--L. Anti-(T,G)-A--L antibodies bind well to the above-mentioned random synthetic polypeptide antigens. Using the ordered synthetic polypeptides, we showed that cells and supernatants of the E-9M(+) line cross-react with (T-T-G-G)-A--L and not with (T-G-T-G)-A--L. The order peptide T-T-G-G represents the major antigenic determinant of the randomly polymerized (T,G)-A--L molecule, and we found that anti-(T,G)-A--L antibodies are bound completely to (T-T-G-G)-A--L and only poorly cross-react with (T-G-T-G)-A--L. Thus, the fine antigenic specificity of cells and factor of the (T,G)-A--L specific E-9M(+) helper T cell continuous line is similar, however not identical, to that of specific antibodies.