Increasing the potency of MHC class II-presented epitopes by linkage to Ii-Key peptide

We previously found that peptide Ii77-92 from the immunoregulatory Ii prote in significantly enhances the binding of antigenic peptides to MHC class II molecules. Now a series of hybrids have been constructed linking LRMK, the active core region of the Ii77-92 peptide, to an antigenic epitope of cyto chrome C. In vitro T cell hybridoma stimulation by some of these hybrids is up to 250 times more potent than by the antigenic peptide. The biological activities of the hybrids were tested in terms of length and composition of the linker. Simple spacers containing a polymethylene bridge (-HN-CH2-CH2- CH2-CH2-CO2-) were fully active in these hybrids which can enhance vaccinat ion with MHC class II-presented epitopes. (C) 2000 Elsevier Science Ltd. Al l rights reserved.