A CELL-FREE SALMONELLA-TYPHIMURIUM EXTRACT INDUCES INHIBITION OF TYROSINE PHOSPHORYLATION IN MURINE SPLENIC T-LYMPHOCYTES

In a previous study, we observed that suppression of T-cell proliferat ion induced by Salmonella infection is associated with inhibition of t yrosine phosphorylation in T-cells, and that a cell-free Salmonella ty phimurium LT2 extract (LT2 extract) also suppressed mitogen-induced T- cell proliferation. In the present study, therefore, we attempted to c larify whether the T-cell suppression induced by LT2 extract involved inhibition of tyrosine phosphorylation in T-cells. Western blotting us ing anti-phosphotyrosine antibodies showed that the mitogen-induced ty rosine phosphorylation of 120-, 106-, 94-, 76-, 68-, 57- and 36-kDa pr oteins in murine splenic T-cells was inhibited by treatment with LT2 e xtract. These results suggest that the suppression of T-cell prolifera tion induced by LT2 extract is also associated with inhibition of tyro sine phosphorylation in T-cells.