Cd4+ T-cell depletion is not associated with alterations in survival, bacterial clearance, and inflammation after cecal ligation and puncture

Our recent studies indicate that mice depleted of T cells that bear the alpha beta T-cell receptor (alpha beta T cells) show less inflammation, less physiological dysfunction, and improved survival after cecal ligation and puncture (CLP) compared with control mice. Classic CD4(+) and CD8(+) T cells comprise most of the up T-cell population. We previously showed that CD8+ T cells, in conjunction with natural killer (NK) cells, participate in CLP-incluced inflammation. However, the contribution of CD4+ T cells to the early inflammatory response caused by CLP is largely undefined. In the present study, we evaluated CLP-induced mortality, bacterial clearance, and inflammation in mice that were depleted of CD4+ T cells. Compared with control mice, CD4 knockout mice and wild-type mice treated with anti-CD4 did not show significant differences in survival, cytokine production, and systemic bacterial counts. The combined depletion of CD4+ T and NK cells resulted in improved survival and decreased cytokine production compared with mice possessing a full lymphocyte complement, especially when CD4+ T and NK cell-deficient mice were treated with imipenem. These improvements were nearly identical to those observed in mice depleted only of NK cells. These studies show that CD4+ T cells do not seem to play a critical role in facilitating the early inflammatory response caused by CLP.