Figure 5

Sepsis impairs lymphocyte IFN-γ and IL-2 production. Peripheral blood mononuclear cells (PBMCs) from septic or critically-ill non-septic (CINS) patients were incubated overnight in media containing isotype control antibody. Blood from septic patients was obtained at three time points during the sepsis, that is, days 1 to 3 (Septic A), days 4 to 7 (Septic B) and days 8 to 12 (Septic C). Samples from days 13 to 21 (Septic D) were not tested. The following morning, cells were stimulated with PMA/ionomycin plus brefeldin for 5 h, washed, immunostained with phenotypic markers to CD3 and CD56, fixed and stained for intracellular interferon (IFN)-γ or interleukin (IL)-2. Flow cytometric analysis revealed a persistent decrease in the percentage of total lymphocytes and natural killer T (NKT) cells that were IFN-γ positive in septic compared to CINS patients throughout most of the septic duration. The difference in IFN-γ production in septic versus CINS patients did not quite reach statistical significance for CD3 T cells, P = 0.07. A similar pattern of decreased IL-2 production in septic versus CINS patients occurred at all septic time points. Data are from 15 septic (21 data points) and 7 CINS patients (7 data points) obtained during their illness. P-values shown are comparison of septic samples with CINS for each draw.