PRIMING OF T-CELL RESPONSES IN MICE BY PORINS OF SALMONELLA-TYPHIMURIUM

An imbalance in signals delivered to T cells via T-cell receptor and a ccessory molecules can lead to anergy, apoptosis, or both. In the pres ent study we have demonstrated that Salmonella typhimurium infection i n mice leads to a progressive loss of CD4(+) T helper (Th) cell popula tion, abnormal T-cell death by apoptosis and loss of accessory molecul es (B7 and intracellular adhesion molecule-1) on macrophages. Quantifi cation of interleukin-2 (IL-2), interleukin-4 (IL-4) and interferon-ga mma (IFN-gamma) secretion revealed a Th2-type of response in lymphocyt es isolated from spleen. However, preimmunization of mice with porins resulted in an increased CD4(+) Th cell population and accessory molec ules on the surface of macrophages. Quantification of cytokines reveal ed a Th1-type of response. We conclude that preimmunization of mice wi th porins provides a microenvironment in which a well-balanced accesso ry molecule and cytokine network is established, which results in the prevention of cell death by apoptosis.