Selective inhibition of antigen presentation to cloned T cells by protease inhibitors.

The effect of eight microbial protease inhibitors on Ag-presentation to six different Ag-specific T cell clones was investigated. We found that these protease inhibitors can inhibit Ag presentation in a highly selective manner. This selectivity was evident with T cell clones specific to different Ag as well as with T cells specific to the same Ag but differing in their H-2 restriction. The inhibition was to due to cytotoxicity or effects through the TCR because none of the eight inhibitors inhibited IL-2-induced T cell proliferation, and because they did not inhibit Ag presentation by fixed APC or synthetic polypeptide. The conclusion after these data suggests that each specific antigenic fragment is produced by a unique set of proteases.