| Abstract: | While regulatory T cells (Tregs) constitutively express programmed cell death‐1 (PD‐1), the role of PD‐1 expression in Tregs of patients with sepsis remains unclear. Thus, we determined PD‐1 expression in Tregs from the peripheral blood of patients with severe sepsis and septic shock. Seventy‐eight patients with severe sepsis and 40 with septic shock, as well as 21 healthy subjects, were enrolled in this study. The percentage of peripheral blood PD‐1+ Tregs, as well as absolute Treg counts, were compared between these three groups. PD‐1 expression in Tregs and absolute Treg counts were also compared between survivors and non‐survivors in patients with sepsis. PD‐1 expression in Tregs increased in patients with sepsis compared to healthy controls. Conversely, absolute Treg counts were significantly decreased in patients with sepsis compared to healthy controls; patients with septic shock had the lowest absolute Treg counts. Among patients with sepsis, survivors had lower levels of PD‐1 expression in Tregs, as well as higher absolute Treg counts, than non‐survivors. Additionally, the percentage of PD‐1+ Tregs correlated positively with lactate levels as well as the Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores in patients with sepsis. PD‐1 was upregulated in Tregs of patients with sepsis and may indicate a state of immune dysfunction. Overexpression of PD‐1 in Tregs was associated with more severe sepsis as well as poor outcomes. |
