Effects of free fatty acids on release of superoxide and on change of shape by human neutrophils. Reversibility by albumin.

Release of superoxide from human neutrophils was stimulated by cis-unsaturated fatty acids (e.g. arachidonate, linoleate). All the saturated and trans-unsaturated fatty acids tested were ineffective in this context. Binding of linoleate to neutrophils was biphasic and could be resolved into a linear and a saturable component. The extent of linoleate binding to the saturable component correlated strongly with the amount of O-2 released (r = 0.96). Palmitate, a saturated fatty acid, exhibited only linear binding to neutrophils and the binding was similar to the linear component of linoleate binding. All cis-unsaturated fatty acids tested decreased the fluorescence polarization of cis- and trans-parinaric acid used as membrane probes in suspensions of neutrophils, whereas the saturated fatty acid, myristate, increased the polarization. Fatty acids which stimulated O-2 release induced morphological changes (i.e. evaginations) in neutrophils, whereas the inactive fatty acids did not affect the cellular morphology. Effects on both the cell morphology and superoxide release were reversed by treatment of the cells with delipidated albumin. These data are discussed in relation to recent reports concerning the effects of free fatty acids on various biochemical systems.