PLATELET-ACTIVATING FACTOR-LIKE ACTIVITY IN MACROPHAGES OBTAINED FROMBRONCHOALVEOLAR LAVAGE FLUID OF ASTHMATIC-PATIENTS

In order to investigate the role of platelet activating factor (PAF) i n the development of bronchial asthma, we examined the PAF-like activi ty in macrophages obtained from bronchoalveolar lavage fluids of patie nts with bronchial asthma and compared it with that in macrophages fro m nonasthmatic subjects. The macrophages were stimulated with f-Met-Le u-Phe (fMLP, 10 mu M) for 15 min. PAF-like activity was detected by ag gregation of washed guinea-pig platelets. The PAF-like activity releas ed from macrophages from asthmatic patients was 34 +/- 17 (S.D.) % agg regation/10(7) cells in the supernatants and 81+/-13% aggregation/10(7 ) cells in the cells themselves. It was found that the PAF-like activi ty in macrophages obtained from non-asthmatic subjects stimulated with f-MLP was 9 +/- 3% aggregation/10(7) cells in the supernatants and 13 +/-5% aggregation/10(7) cells in the cells. There was no aggregation r esponse in the supernatants and in the cells of macrophages in either of the-groups without f-MLP stimulation. The results show that PAF-lik e activity was significantly greater in the macrophages obtained from the asthmatic patients than that in the macrophages obtained from non- asthmatic subjects, suggesting that macrophages are involved in the de velopment of bronchial asthma by releasing more PAF-like activity.