Inhibition of human polymorphonuclear leukocyte respiratory burst activity and aggregation by 6-ketocholestanol

6-ketocholestanol, a naturally occurring oxygenated sterol, when incubated with human neutrophils (PMN), can inhibit superoxide and hydrogen peroxide generation in a dose-dependent fashion. This is accompanied by inhibition of stimulated PMN aggregation without alteration in cellular viability. This inhibitory effect is not affected by washing of the cells, and cannot be blocked by the addition of free cholesterol to the medium. These data are consistent with prior observations which showed an inhibitory effect on PMN chemotaxis by certain oxygenated sterol compounds, and support the hypothesis that certain oxygenated sterols can affect a variety of human PMN functions by a mechanism that may involve perturbation of the plasma membrane.