Positional effect of amino acid replacement on peptide antigens for the enhancement of IFNg production

Abstract

Rationale Since certain amino acid replacement on peptide antigens induce increased IFNg production from CD4T cell clones, we investigated if specific position of peptide is prone to induce such a change. Methods Human Th0 clones BC20, BC33, and BC42 express distinct TCRa and TCRb but recognize the same TCR ligand; i.e., the same framework of peptide antigen BCGa84-100 in the context of DRB1 ∗1405. We stimulated these T cells with various analogue peptide with one residue replacement, and determined their proliferation and IFNg production. Results Increased IFNg productin was observed, if position 2 of BCGa84-100 was replaced by more hydrophobic residues. Such a change was associated with the structure of CDR3 of TCRa. Conclusions Thus structure-function relationship is apparent in increased IFNg production induced by analogue peptide.