RELATIONSHIP BETWEEN SOLUBLE CD14, LIPOPOLYSACCHARIDE-BINDING PROTEIN, AND THE ALVEOLAR INFLAMMATORY RESPONSE IN PATIENTS WITH ACUTE RESPIRATORY-DISTRESS SYNDROME

The effects of bacterial endotoxin (lipopolysaccharide, LPS) are ampli fied by lipopolysaccharide binding protein (LBP) and CD14, resulting i n cellular activation at very low concentrations of LPS. To investigat e the importance of this pathway in acute lung injury, we measured LPS , LBP, and soluble CD14 (sCD14) in the bronchoalveolar lavage fluid (B AL) of 82 patients with acute respiratory distress syndrome (ARDS). LB P and sCD14 increased markedly in BAL of patients with ARDS. BAL sCD14 and LBP each were strongly related to BAL total protein and polymorph onuclear neutrophil (PMN) concentration, whereas LPS concentration was not. Multivariate analyses showed sCD14 to be strongly related to BAL total protein, even after controlling for LPS and LBP concentrations. sCD14 was strongly and independently related to PMN concentration, af ter controlling for BAL LPS, LBP, and interleukin-8 (IL-8). The BAL LP S concentration was not strongly related to either BAL total protein o r BAL PMN. The BAL sCD14 and LBP values were similar in all subgroups of patients with ARDS, and were not related to survival. The serum LBP and sCD14 were elevated in ARDS, but were not related to BAL total pr otein, LBP, sCD14, PMN, or clinical outcome. Thus, LBP and sCD14 reach high concentrations in the lungs of patients with ARDS, and BAL sCD14 is strongly related to two major indices of lung inflammation: total protein and PMN concentration. CD14-dependent mechanisms may contribut e to lung inflammation in ARDS.