Modulation of degranulation and superoxide generation in human neutrophils by unsaturated fatty acids of odd carbon numbers.

Unsaturated fatty acids of odd carbons, 13:1(12), 17:1(10trans), 19:1(7) and 19:1(10) inhibited release of myeloperoxidase (MPO) from fMet-Leu-Phe-cytochalasin B-treated neutrophils. The inhibitory effect was smaller than that of aseanostatins which have been isolated as microbial-derived free fatty acids with a methyl blanch (i-14:0 and ai-15:0) (Journal of Antibiotics (1991) 44, 524-532). These unsaturated fatty acids also inhibited lactoferrin release by the same treatment. On the other hand, 13:1(12), 15:1(10) and 19:1(10) inhibited fMet-Leu-Phe-stimulated superoxide generation of neutrophils, and the fatty acids 15:1(10), 17:(10) and 19:2(10,13) induced superoxide generation in both unstimulated cells and the cell-free system. However, none of unsaturated fatty acids of odd carbons tested inhibited beta-glucuronidase release, whereas 15:1(10), 17:1(10), 19:1(10) and 19:2(10,13) rather enhanced an increase in beta-glucuronidase activity liberated from cells at high concentrations over 35 microM, indicating cellular damages by these fatty acids. These observations suggest that unsaturated free fatty acids having odd carbons such as 13, 15, 17 and 19 may act as modulators of neutrophil functions including degranulation and superoxide generation.