Superantigen-induzierte Effekte auf die Expression des IL-2 Rezeptors und Proliferation von CD4- und CD8-positiven T-Zellen in der Ratte

Activation of Vb-specific T cells by bacterial superantigens leads to a polyclonal immune response of large numbers of T lymphocytes. In the human system, superantigenic infection represents the main cause for food poisoning with a high risk of developing septic shock. The immune stimulating effects of superantigens in mice have been sufficiently investigated, whereas the effects in rats are still unclear. The aim of this work is to show the in vivo effects of staphylococcal enterotoxin A (SEA) on lymphocytes in different immune organs of the rat. There are currently no data being published on this issue. Serum samples and lymphatic tissues were obtained at different points of time after SEA injection. Elevated serum levels of IL-2 and IL-6 demonstrate a strong immunomodulatory effect of SEA. In situ hybridization detection of IL-2 receptor alpha mRNA in the periarteriolar lymphatic sheath (PALS) of the spleen, a T lymphocyte specific compartment, demonstrates a T cell mediated immunoreaction. PCR on tissue samples of the PALS gathered by Laser Capture Micro dissection (LCM) showed positive IL-2 receptor alpha mRNA levels compared to other regions of the spleen. Increased numbers of CD4+ and CD8+ lymphocytes, which additionally expressed the IL-2 receptor alpha chain (CD25) on their surface, were measured by FACS-analysis. The expected strong mitogenic effect of SEA on IL-2 receptor positive cells was finally approved by high proliferation rates of splenocytes, thymocytes and cells of mesenterial lymph nodes. Comparably to the human system, SEA can be characterized as a strong activator of the peripheral immune system of the rat.