CHANGES OF FATTY-ACID COMPOSITION AND OXIDATIVE-METABOLISM OF HUMAN NEUTROPHILS MIGRATING INTO AN INFLAMMATORY EXUDATE

The peripheral blood neutrophils and the neutrophils accumulated into a skin-window experimental exudate were compared for their ability to release super-oxide anion (O-2(-)) and for their fatty acid compositio n, determined by capillary gas-chromatography. The basal O-2(-) releas e and the phorbol myristate acetate (PMA)-induced O-2(-) release were not significantly different in the two neutrophil populations, while i n response to formyl-methionyl-leucyl-phenylalanine (fMLP) the exudate cells showed an activity that was two fold higher than that of blood cells. The most significant changes of fatty acid composition of exuda te versus blood cells were the following: i) increase of C16:0 (palmit ic acid) from 21.3 +/- 1.2% to 23.5 +/- 1.3% (+10.2%) of total fatty a cids (p < 0.001), ii) increase of C18:2 (linoleic acid) from 9.3 +/- 1 .7% to 11.0 +/- 2.1% (+ 18.3%) (p = 0.005), iii) decrease of C20:4 (ar achidonic acid) from 12.8 +/- 1.6% to 10.6 +/- 1.2% (-17.3%) (p < 0.00 1), whereas C18:1 (oleic acid) did not change. The total content of sa turated or unsaturated fatty acids did not change. In exudate cells, a strong negative correlation was found between palmitic acid content a nd 0; release in response to both fMLP and PMA (r = -0.52, p < 0.02 an d r = -0.49, p < 0.05, respectively) whereas arachidonic acid correlat ed positively, but weakly, with O-2(-) (r = 0.40, p = 0.07 and r = 0.4 7, p = 0.05, with fMLP and PMA as stimulants respectively). A positive correlation was also found between the arachidonic acid content of bl ood cells and the number of cells that migrated into the inflammatory exudate. These results indicate that the process of extravasation from blood into the exudate causes specific and consistent modifications o f the fatty acid composition of neutrophils and suggest that these mod ifications have a role in the activation and the regulation of the O-2 (-) forming system.