Group II phospholipase A2 (membrane-associated phospholipase A2, M-PLA2) hydrolyses the 2-acyl position of a glycerophospholipid. The concentrations of M-PLA2 in serum and bronchoalveolar lavage fluid (BALF) were measured in 13 asymptomatic cigarette smokers without clinically detectable lung disease, and the results were compared with those in 13 healthy non-smokers, using a specific radioimmunoassay. In addition, Northern blot analysis of M-PLA2 mRNA was performed in preparations of total RNA extracted from the cell pellet of BALF from two smokers and two non-smokers. No significant difference was found in serum M-PLA2 levels between 13 smokers (mean +/- SD, 3.48 +/- 1.21 ng ml-1) and 13 non-smokers (3.12 +/- 1.06 ng ml-1). The smokers' BALFs contained significantly greater levels of M-PLA2 compared with the non-smokers', whether expressed in terms of BALF volume (0.59 +/- 0.34 vs. 0.12 +/- 0.09 ng ml-1, P < 0.001) or protein content (7.22 +/- 3.17 vs. 2.31 +/- 1.48 ng mg-1 protein, P < 0.001). Northern analysis showed that the levels of M-PLA2 mRNA in two smokers were greater than those in two non-smokers. Thus, cigarette smoking was associated with increased levels of M-PLA2 in BALF. This enzyme may be involved in the pathogenesis of pulmonary disease associated with cigarette smoking.