EVIDENCE SUPPORTING A ROLE FOR CATHEPSIN-B IN THE GENERATION OF T-CELL ANTIGENIC EPITOPES OF HUMAN GROWTH-HORMONE

The elucidation of the enzymatic processing mechanism associated with the formation of antigenic peptide fragments that combine with MHC cla ss II molecules is fundamental to our understanding of the immune syst em. We have investigated a structurally well defined protein, recombin ant human growth hormone (rhGH), as an antigen, and present data suppo rting the hypothesis that the enzyme cathepsin B can produce peptide f ragments bearing T cell epitopes associated with lymphocyte proliferat ive response to hGH in Balb/c (H-2(d)haplotype) mice. Minimal T cell e pitopes are not generated; rather the cathepsin cleavage sites flank t he three antigenic peptide regions, amino acid residues 31 41, 81-100, and 166-181.