Increased PMN CD11b/CD18 expression following post-traumatic ARDS.

We investigated the role of polymorphonuclear leukocytes (PMN) in the pathogenesis of post-traumatic adult respiratory distress syndrome (ARDS). Two groups of patients were studied: Group I (n = 29) represents trauma patients studied within 24 hr of admission to the SICU, and Group II (n = 10) represents a subset of Group I patients who subsequently developed ARDS. Circulating pulmonary artery PMN were then assayed for CD11b/CD18 expression, MTT-Formazan production, intracellular H2O2 production, and superoxide anion release. PMN from Group II patients were upregulated with regard to all of the PMN functions assayed within 24 hr of the diagnosis of ARDS being made. Subsequently, longitudinal assays were performed on 17 patients at risk for the development of ARDS. In 6 of 7 patients prior to the clinical recognition of ARDS, CD11b/CD18 expression and MTT-Formazan production increased significantly over baseline. These results suggest that: (i) ARDS coincides with increased CD11b/CD18 expression on PMN cell surfaces, (ii) PMN oxidative metabolism increases at the onset of ARDS, and (iii) changes in circulating pulmonary artery PMN may provide markers for the development of ARDS in the traumatized patient.