Surfactant protein A decreases lung injury and mortality after murine marrow transplantation

Surfactant protein A (SP-A), a collectin associated with surfactant liplids, can have immune modulatory effects. We hypothesized that exogenous and basal endogenous SP-A can function to suppress donor T-cell-dependent inflammation that occurs during the generation of idiopathic pneumonia syndrome after bone marrow transplantation (BMT). Wild type and SP-A-deficient mice were conditioned with cyclophosphamide and lethal irradiation and then given allogeneic donor bone marrow plus inflammation-inducing spleen T cells. On Day 7 after BMT, bronchoalveolar lavage fluids from SP-A-deficient mice contained increased numbers of inflammatory cells and higher levels of proinflammatory mediators tumor necrosis factor-alpha, interferon-gamma, and nitric oxide than wild-type mice. Exaggerated inflammation in SP-A-deficient mice was associated with decreased dynamic lung compliance and increased donor T-cell-dependent mortality (P=0.0007, n=10). Nitrative stress in alveolar macrophages from SIP-A(+/+) conditioned BMT recipients was higher than for SP-A(+/+) mice. Similarly, mice treated with transtracheal human SP-A (50 jig), instilled on Day 4 after BMT during a time of in vivo donor T cell activation, exhibited decreased inflammation and improved early survival compared with buffer-instilled mice. We concluded that basal endogenous SP-A and enhanced alveolar SP-A level modulate donor T-cell-dependent immune responses and prolong survival after allogeneic BMT.