Objective-Leukocytes are activated in women with preeclampsia, but the class of leukocytes that infiltrates the maternal vasculature and, therefore, most likely to cause vascular dysfunction is not known.Methods-Subcutaneous fat biopsies were obtained at cesarean section or abdominal surgery from 7 normal nonpregnant women, 7 normal pregnant women, and 7 preeclamptic women. Tissues were immunohistochemically stained for CD14, a monocyte/macrophage antigen, CD99, a lymphocyte antigen, and CD66b, a neutrophil antigen.Results-CD14 stained cells were found infiltrated into fat tissue but were not present in vessels for any of the groups. CD99 stained cells were present in approximately 20-30% of vessels with no difference among groups. CD66b stained cells were present in all groups with a significantly greater percentage of vessels stained for preeclamptic than normal pregnant or normal nonpregnant women (70±6 vs. 43±9 vs. 21±5%, respectively, P<0.01). CD66b cells were the most abundant cell type that infiltrated vessels of preeclamptic women. Conclusions-1)There was significantly more neutrophils adhered to endothelium and infiltrated into the intimal space in the maternal systemic vasculature of preeclamptic women than in normal pregnant women or normal nonpregnant women; 2) There was no significant difference in lymphocyte infiltration among the patient groups and lymphocytes were present in much lower numbers than neutrophils; 3) Monocytes/macrophages were found in fat tissue but not in vessels. We speculate that neutrophils are the class of leukocytes that cause the majority of vascular cell dysfunction in preeclamptic women.

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