T cell subsets in human airways prior to and following endobronchial administration of endotoxin

Background and objectives Bronchial instillation of lipopolysaccharide ( LPS ) provides a reversible model of lung inflammation that may resemble early stages of acute respiratory distress syndrome ( ARDS ). We investigated the distributions of T ‐cell subsets in the human airways and sought to determine whether pro‐ and anti‐inflammatory T cells are involved in the local immune response to lung inflammation. Methods Bronchoalveolar lavage ( BAL ) was performed in 15 healthy volunteers, after which E scherichia coli   LPS (4 ng/kg) was administered. BAL was repeated at 2, 4, 6, 8 or 24 h after instillation of LPS . Results BALF CD 4+ and CD 8+ T cells were characterized by expression of activation markers ( HLA‐DR + CD 38+), the proportion of cells expressing naïve markers ( CD 45 RA + CD 27+ CCR 7+) was lower, and that of cells expressing effector memory markers ( CD 45RA‐ CD 27+ CCR 7‐) was higher, compared with peripheral blood. Bronchial LPS induced a local inflammatory response with recruitment of CD 4+ ( P  = 0.014), CD 8+ T cells ( P  = 0.034), an increase in the proportion of CD 4+ CD 25+ CD 127low F oxp3+ regulatory T cells ( T regs) ( P  = 0.045) and a tendency towards an increase in CD 4+ CD 161+ cells ( P  = 0.071) were observed. Conclusions A unique distribution of T cells with little day‐to‐day variation was found in human airways. An increase in T regs after endobronchial LPS suggests a role for T regs during early stages of pulmonary inflammation.