POLYUNSATURATED FATTY-ACIDS INCREASE NEUTROPHIL ADHERENCE AND INTEGRIN RECEPTOR EXPRESSION

Fish oils are abundant in polyunsaturated fatty acids of the n-3 serie s (in particular eicosapentaenoic, 20:5 and docosahexaenoic acid, 22:6 ). Such fatty acids are generally considered to be beneficial in the p revention of cardiac disease and to have anti-inflammatory properties. Neutrophil adherence is an essential early event in an acute inflamma tory response, and we have demonstrated that both 20:5 and 22:6 stimul ate adherence in vitro. Arachidonic acid (20:4, n-6) was also stimulat ory. Significant stimulation of adherence was seen from 5 to 80 muM (n ontoxic concentrations) 22:6, 20:5, or 20:4. At the lower fatty acid c oncentrations tested (less-than-or-equal-to 40 muM) 20:5 was less acti ve than 22:6 or 20:4 at stimulating adherence. Above 40 muM there was no difference in the ability of the three fatty acids to stimulate adh erence. At the lower fatty acid concentrations tested (less-than-or-eq ual-to 10 muM) 22:6 was less active than 20:4, whereas above 10 muM th ey were equally active. Immunofluorescent flow cytometric analysis of neutrophil integrin (adherence) receptors showed that the complement C 3bi receptor (CD11b) was up-regulated by these fatty acids. There was no change in CD11a or CD11c. Saturated fatty acids of the same chain l ength were without effect on adherence or receptor expression. The fin dings suggest that these polyunsaturated fatty acids may, under certai n conditions, be proinflammatory with respect to their acute effects o n the interaction of neutrophils with microbes, endothelium, and other tissues.