1. Neutrophil activation was examined in 22 women with pre-eclampsia and 22 age- and gestation-matched control subjects using whole-blood flow cytometry to assess basal and platelet-activating factor stimulated CD11b and CD18.
2. Basal neutrophil CD11b expression was significantly increased in women with pre-eclampsia compared with normal pregnancy before delivery. A similar non-significant trend for CD18 was also observed.
3. Before delivery, neutrophil CD11b expression increased in a dose-dependent fashion after platelet-activating factor stimulation, with the differences between the groups maintained. A similar dose-dependent increase in CD18 expression was observed after platelet-activating factor.
4. There were no between-group differences in expression of either CD11b or CD18 at either 6 weeks or 6 months post partum, either before or after platelet-activating factor stimulation.
5. Neutrophil CD11b was positively correlated with plasma uric acid (r = 0.44, P = 0.04) in women with pre-eclampsia, suggesting that the extent of neutrophil activation correlates with disease severity.
6. An increase in basal neutrophil CD11b expression in women with pre-eclampsia is likely to be an index of neutrophil activation in vivo. Neutrophil release of free radicals and proteases may then help perpetuate a vicious cycle of endothelial and vascular dysfunction in the placental and systemic circulations. The cause of this activation is not known but could involve platelet activation, increased production of endothelin-1 or release of cytokines. Further studies will be required to elucidate the consequences of neutrophil activation in pre-eclampsia.