CHARACTERIZATION OF SIGNAL-TRANSDUCTION THROUGH THE TCR-ZETA CHAIN FOLLOWING T-CELL STIMULATION WITH ANALOG PEPTIDES OF TYPE-II COLLAGEN-260-267

The immunodominant T cell determinant of type II collagen (CII) recogn ized by DBA/1 mice (I-A(q)) is CII 260-267. The aims of this study wer e to determine the role of the amino acid residues within CII 245-270 in T cell signal transduction. To that end, we utilized I-Ag-restricte d, CII-specific T cell hybridomas and examined tyrosine phosphorylatio n of TCR-zeta following stimulation with either wild-type CII 245-270 or a panel of analogue peptides. A variety of patterns occurred, rangi ng from increased phosphorylation of TCR-zeta to either partial or a c omplete abrogation of phosphorylation. Critical substitutions also com pletely abrogated the phosphorylation of ZAP70, a downstream molecule in TCR-zeta signaling. Evaluation of the supernatants of the T cell hy bridomas for cytokine production in response to the peptides revealed a dose correlation between the induction of phosphorylation of TCR-zet a and the amount of cytokine induced. Selected analogue peptides were tested as tolerogens in neonatal mice. Analogues that did not induce t he phosphorylation of zeta chain, such as B3 (CII 251-270s263F-->N), w ere completely unable to induce tolerance, while analogues that caused a partial phosphorylation, such as B6 (CII 251-270s267Q-->T) and A3 ( CII 245-270s269P-->A), induced partial tolerance judged by intermediat e degrees of suppression of arthritis. We conclude that discrete alter ations in specific amino acid residues of antigenic peptides had profo und effects on T cell signaling and that the signaling correlated with T cell cytokine secretion and T cell function in the induction of tol erance and suppression of arthritis.