Polymorphonuclear leukocytes (PMN) are the predominant inflammatory cells recruited in acute lung injury. This study compares the concentration of interleukin-8 (IL-8) to those of GRO alpha, both of which are CXC chemokines, in bronchoalveolar lavage fluid (BALF) in three acute pathologic states: bacterial pneumonia (BPN); adult respiratory distress syndrome (ARDS); and Pneumocystis carinii pneumonia (PCP). Levels of both IL-8 and GRO alpha were below 5 pg/ml in 16 nonsmoking volunteers who served as controls. Despite more than twice as many neutrophils in the BALF of the BPN group (n = 12) than in the group with ARDS (n = 13), both groups had similar levels of IL-8, of 569 +/- 120 pg/ml and 507 +/- 96 pg/ml, respectively. The GRO alpha concentrations in the BPN and ARDS patients were respectively 3.3 and 3.4 times those of IL-8, reaching 1,870 +/- 314 pg/ml for the BPN and 1,699 +/- 377 for the ARDS patients. In the PCP group (n = 48, 45 human immunodeficiency virus [HIV]-positive, 3 HIV-negative), GRO alpha levels (897 +/- 172 pg/ml) were sevenfold higher than IL-8 levels (123 +/- 40 pg/ml). In all pathologic states there was a good correlation between GRO alpha and IL-8 (r = 0.53, p = 0.0001). GRO alpha or IL-8 both correlate with the absolute neutrophil number/ml when all groups were studied together (r = 0.52, p = 0.0001). Only in the PCP and ARDS groups did IL-8 correlate with the PMN number.(ABSTRACT TRUNCATED AT 250 WORDS)