HIGH-LEVELS OF INTERLEUKIN-8 IN THE BLOOD AND ALVEOLAR SPACES OF PATIENTS WITH PNEUMONIA AND ADULT-RESPIRATORY-DISTRESS-SYNDROME

There is ample experimental evidence that polymorphonuclear neutrophil s (PMN) play a critical role in the pathogenesis of the adult respirat ory distress syndrome (ARDS). Since interleukin-8 (IL-8) is a strong c hemotactic factor for PMN, we measured IL-8 levels in plasma and bronc hoalveolar lavage (BAL) fluid of 18 patients, 12 with ARDS and 6 with severe pneumonia uncomplicated by ARDS, all of whom had an increased n umber of PMN in BAL fluid. Seven healthy subjects served as controls. We found elevated levels of IL-8 in the alveolar spaces of all patient s tested. Elevated BAL IL-8 levels were related to a fatal outcome and the presence of shock and correlated with a general clinical severity index (simplified acute physiological score). BAL fluid levels of IL- 8 were significantly higher in patients with ARDS than in patients wit h pneumonia. In plasma, IL-8 levels were increased similarly in all pa tients and did not correlate with survival or the presence of shock. T he BAL fluid-to-plasma ratio of IL-8 was significantly greater than th at of tumor necrosis factor alpha, indicating higher local production of IL-8. Moreover, the presence of a primed subpopulation of blood PMN with respect to H2O2 production indicates that IL-8 may contribute to the neutrophil-mediated process in the pathogenesis of ARDS and pneum onia.