Inflammation-Induced Changes in Circulating T-Cell Subsets and Cytokine Production During Human Endotoxemia.

Observational clinical studies suggest the initial phase of sepsis may involve impaired cellular immunity. In the present study, we investigated temporal changes in T-cell subsets and T-cell cytokine production during human endotoxemia. Endotoxin (Escherichia coli lipopolysaccharide 4 ng/kg) was administered intravenously in 15 healthy volunteers. Peripheral blood and bronchoalveolar lavage fluid (BALF) were collected at baseline and after 2, 4, 6, 8, and 24 hours for flow cytometry. CD4CD25CD127lowFoxp3 regulatory T cells (Tregs), CD4CD161 cells, and activated Human leukocyte antigen, HLA-DRCD38 T cells were determined. Ex vivo whole-blood cytokine production and Toll-like receptor (TLR)-4 expression on Tregs were measured. Absolute number of CD3CD4 (P = .026), CD3CD8 (P = .046), Tregs (P = .023), and CD4CD161 cells (P = .042) decreased after endotoxin administration. The frequency of anti-inflammatory Tregs increased (P = .033), whereas the frequency of proinflammatory CD4CD161 cells decreased (P = .034). Endotoxemia was associated with impaired whole-blood production of tumor necrosis factor-α, interleukin-10, IL-6, IL-17, IL-2, and interferon-γ in response to phytohaemagglutinin but did not affect TLR4 expression on Tregs. No changes in the absolute count or frequency of BALF T cells were observed. Systemic inflammation is associated with lymphopenia, a relative increase in the frequency of anti-inflammatory Tregs, and a functional impairment of T-cell cytokine production.