RESUMO
BACKGROUND: The immune balance controlled by T-helper (Th)1 and Th2 cells is critical in protecting the host from pathogenic invasion, and its imbalance may increase susceptibility to infection in patients undergoing major surgery. The differentiation of naive T cells to Th1 and Th2 cells is largely driven by cytokines. In addition, steroid hormones have been shown to affect Th1/Th2 balance, particularly in autoimmune diseases. The regulation of Th1/Th2 balance in patients undergoing surgery and its potential clinical relevance remain unclear. MATERIALS AND METHODS: Blood samples were obtained from patients both before and 2 h after major abdominal surgery. Peripheral blood mononuclear cells were isolated and cultured in wells coated with either anti-CD3 (direct T-cell stimulation) or phytohemagglutinin (PHA) (indirect T-cell stimulation), with or without 10(-5) M dehydroepiandrosterone (DHEA). The release of interleukin (IL)-2, interferon gamma, and IL-10 was measured by an enzyme-linked immunosorbent assay, and the expression of CD4, CD8, and CD69 was determined by flow cytometry. RESULTS: DHEA decreased the release of IL-2 and IL-10 in directly (anti-CD3) and indirectly (PHA)-stimulated T cells from postoperative samples, whereas the release of interferon gamma in PHA-stimulated T cells was not affected. The distribution of CD4/CD8 was not significantly different after surgery or DHEA. DHEA was associated with a decrease in the expression of the activation marker CD69 on CD4(+) T cells, whereas the activation of CD8(+) T cells remained unchanged. CONCLUSIONS: These results demonstrate that DHEA plays a critical role in controlling Th1/Th2 balance in the immediate postoperative period. Attenuation of both the Th1 and Th2 responses has been suggested to have immunoprotective effects. The role of DHEA in the regulation of Th1/Th2 balance in patients undergoing major abdominal surgery may, therefore, also be of significant clinical relevance and warrants further investigation.