Complement C3 depletion links to the expansion of regulatory T cells and compromises T-cell immunity in human abdominal sepsis: A prospective pilot study

Purpose

Complement depletion commonly occurred in septic patients, but this problem was often underestimated during the treatment process. This study was designed to determine the association between complement depletion and T-cell immunosuppression.

Methods

From November 2011 to March 2012, patients with severe abdominal sepsis were prospectively enrolled in a single center. The baseline levels of complement C3 were used to stratify subjects into 2 groups. Plasma levels of complement components, percentage of regulatory T cells (Tregs), and T-cell immunity indexes were monitored at times after admission. The relationship between C3 depletion and T-cell response was investigated, with clinical outcomes explored meanwhile.

Results

A total of 60 patients aged 43.9 ± 11.3 years were included within the period. C3 depletion, occurring in 65% of enrolled subjects, was strongly correlated with Treg expansion (P = .001) and decreased CD4⁺/CD8⁺ ratio (P = .008). This depletion was also related to prolonged hospital stay (P = .001), delayed time to operation (P < .001), increased postoperative complications (P = .036), and hospital expenditure (P < .001).

Conclusions

Complement C3 depletion was found to be linked to the expansion of Tregs during abdominal sepsis. Such depletion and associated immunosuppression should be paid close attention in the critical care.