N-6 AND N-3 POLYUNSATURATED FATTY-ACIDS STIMULATE TRANSLOCATION OF PROTEIN-KINASE-C-ALPHA, PROTEIN-KINASE-C-BETA-I, PROTEIN-KINASE-C-BETA-II AND PROTEIN-KINASE-C-EPSILON AND ENHANCE AGONIST-INDUCED NADPH OXIDASE IN MACROPHAGES

The polyunsaturated fatty acids (PUFA), arachidonic acid (AA), eicosap entaenoic acid (EPA) and docosahexaenoic acid (DHA) were poor inducers of oxygen-dependent respiratory activity (chemiluminescence) in human monocytes and macrophages, but markedly enhanced the response to the tripeptide, N-formylmethionyl-leucyl-phenylalanine. The effects of the se fatty acids were seen at concentrations of 1 mu g/ml. A similar enh ancement was seen with PMA, a stimulus that acts on protein kinase C ( PKC), or calcium ionophore (A23187), which increases intracellular cal cium, suggesting that the effect of the fatty acids was post-surface r eceptor binding, HL-60 cells, differentiated to macrophage-like cells by culture in the presence of vitamin D-3, were similarly affected by the fatty acids. In experiments in which the time of pre-exposure of t he monocytes to PUFA was varied, it was found that the priming effect induced by PLA, EPA and DHA was maximal at 5 min. The ability of these fatty acids to synergize with other agonists was completely lost if t he fatty acids were either methylated or oxidized to the hydro and hyd roperoxy derivatives. Saturated fatty acids were inactive, Western blo t analysis demonstrated that the PUFA induced the translocation of PKC alpha, -beta I, -beta II and -epsilon isoenzymes to a particulate fra ction. The synergistic response between fatty acids and A23187 was com pletely inhibited by pretreating the cells with a PKC inhibitor, GF-10 9203X, or by pretreatment of monocytes with PMA for 18 h, to deplete P KC levels. From these investigations it is evident that PUFA prime mac rophages, causing increased/synergistic oxidative respiratory burst ac tivity to other stimuli and that this priming is dependent on PKC tran slocation and activation.