A purified protein from Salmonella typhimurium inhibits proliferation of murine splenic anti-CD3 antibody-activated T-lymphocytes

FEMS Immunol Med Microbiol. 1996 Jun;14(2-3):121-7. doi: 10.1111/j.1574-695X.1996.tb00278.x.


In previous study, we observed that the purified substance Salmonella typhimurium-derived inhibitor of T-cell proliferation (STI) had an immunosuppressive effect, demonstrated as the suppression of mitogenic lectin-induced proliferation of murine spleen cells. In the present study, we confirmed the immunosuppressive effect of STI, which suppressed the proliferation of murine splenic T-lymphocytes activated with the anti-CD3 antibody (Ab) and phorbol 12-myristate-13 acetate (PMA) and this phenomenon was accompanied by augmentation of interferon-gamma (IFN-gamma) secretion and inhibition of interleukin-2 (IL-2) secretion. Furthermore, the augmentation of IFN-gamma secretion caused IL-2 receptor alpha chain (IL-2R alpha) over expression on T-cells. However, the addition of an anti-IFN-gamma Ab and recombinant IL-2 (rIL-2) did not reverse the suppressed T-cell proliferation, although the level of IL-2R alpha expression on T-cells recovered to around normal. Furthermore, Western blotting using an anti-phosphotyrosine Ab showed that IL-2R-mediated tyrosine phosphorylation of protein substrates in T-cells was inhibited by incubation with STI for 48 h and this inhibition was not reversed by adding the anti-IFN-gamma Ab and rIL-2. These results suggest that STI-induced suppression of T-cell proliferation involves a defect in IL-2R function and/or IL-2 signaling pathway in T-cells.

MeSH terms

  • Animals
  • Bacterial Proteins
  • CD3 Complex / metabolism*
  • Cells, Cultured
  • Immunosuppressive Agents / pharmacology*
  • Interferon-gamma / metabolism
  • Interleukin-2 / metabolism
  • Interleukin-2 / pharmacology
  • Lymphocyte Activation / drug effects*
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Phosphorylation
  • Receptors, Interleukin-2 / metabolism
  • Salmonella typhimurium / chemistry*
  • Salmonella typhimurium / pathogenicity
  • Spleen / cytology
  • T-Lymphocytes / drug effects*
  • Tetradecanoylphorbol Acetate / pharmacology
  • Tyrosine / metabolism


  • Bacterial Proteins
  • CD3 Complex
  • Immunosuppressive Agents
  • Interleukin-2
  • Receptors, Interleukin-2
  • Tyrosine
  • Interferon-gamma
  • Tetradecanoylphorbol Acetate