The Mechanism of Antigen-presentation of Porin from Salmonella typhimurium to T Lymphocytes

Abstract

Porins from wild type strains of Salmonella typhimurium are known to consist of three species of proteins named 34, 35 and 36K. It is understood that these three species of proteins construct porin trimers and the porin trimers from the wild type strain of S. typhimurium are constructed from homologous species of porin subunits. However, we have demonstrated previously that only porin trimers from wild type strains but not mixtures of homologous porin trimers from mutant strains of S. typhimurium could induce antigen-specific cell-mediated immunity (CMI). In this study, therefore, a mechanism of antigen-presentation of porin from a wild type strain of S. typhimurium to T cells was studied. Our data showed that porin proteins from the wild type strain received antigen-processing as well as other protein antigens in murine macrophages and were presented with Ia antigen to T cells. These results suggested that porin trimers from wild type strains of S. typhimurium were constructed from heterologous species of porin subunits and only heterologous porin trimers held epitopes for a CMI-eliciting antigen.