Especially on subjects suffering from trauma, recent major surgery or sepsis, several authors shown that different parameters obtained from the blood count [i.e., absolute lymphocyte count (ALC) and lymphocyte subsets, such as CD4/CD8 and regulatory T cell] are suitable biomarkers for evaluating the immune function in critically ill patients and strongly correlated to prognosis [8, 9]. This evidence concerns the gene CD4 and Sepsis.