Overexpression of programmed cell death-1 on circulatory Th1 and Th2 cells in cardiac arrest patients in the early period after the return of spontaneous circulation

Background: In patients with immune disorders, the role of T-helper (Th) cells immediately following the return of spontaneous circulation (ROSC) after cardiac arrest is unclear. We evaluated the influence of plasma cytokine and programmed cell death-1 (PD-1) expression on circulating Th1 and Th2 cells and elucidated their role in immune function immediately following ROSC. Methods: We enrolled 92 non-consecutive cardiac arrest patients that experienced ROSC between 6 and 24 h post-cardiac arrest as well as 40 healthy controls. Outcome data were collected 28 days after ROSC. Peripheral blood samples were analyzed to determine Th1 and Th2 cell counts and PD-1 expression. The plasma levels of cytokines, including interferon-γ, tumor necrosis factor-α, interleukin (IL)-4, IL-6, and IL-10 were determined. Results: Compared with those in healthy individuals, Th1 and Th2 cell counts and Th1/Th2 cell ratios in CA patients after ROSC were significantly reduced (P < 0.05). The percentages of PD-1 expression were significantly higher in Th1 and Th2 cells (P < 0.01). There were no significant differences in Th1 and Th2 cell expression of PD-1 between survivors and non-survivors. Plasma levels of IL-6 and IL-10 in ROSC patients were significantly higher during the early period (P < 0.05). Conclusions: Th1 and Th2 cell expression of PD-1 is upregulated in the period immediately following ROSC in cardiac arrest patients and may be responsible for the observed immunosuppression in these patients during this period.