SepsisThe early phase of human sepsis is characterized by a combination of apoptosis and proliferation of T cells

PurposeT cell activation as well as unresponsiveness has been described in separate studies in sepsis. Our aim was to establish the coexistence of both T cell fate in human sepsis.Patients and MethodsThis is a cross-sectional study of 48 patients presenting with severe sepsis or septic shock and 15 healthy controls. Cytofluorometric techniques were used to quantify T cell activation, apoptosis, proliferation, expression of costimulatory molecules, and cytokine secretion.ResultsPatients with sepsis were characterized by a significant increase in the percentage of activated T cell subsets, as measured using CD69 marker, compared with healthy controls (P < .05). T cell proliferation as measured through Ki67 expression was obvious in infected patients for both CD4 and CD8 T cell subsets compared with controls (P ≤ .006). T cell subset apoptosis as measured using Hoechst dye was also increased in infected patients compared with controls (P ≤ .002). CD4 T cell proliferation was correlated with interleukin 2 secretion (R2 = 0.84, P < .001), whereas up-regulation of CD4 T cell apoptosis was correlated with CTLA-4 expression (R2 = 0.24, P = .001). No such similar relationship was observed for CD8+ T cells.ConclusionsConcomitant T cell proliferation and T cell apoptosis are observed in human sepsis, being related to a different pathway.