Neutrophils, but not lymphocytes or monocytes, infiltrate maternal systemic vasculature in women with preeclampsia

Abstract

Objective: Leukocytes are activated in women with preeclampsia, but the class of leukocytes that infiltrates the maternal vasculature and, therefore, is most likely to cause vascular dysfunction is not known.

Methods: Subcutaneous fat biopsies were obtained at Cesarean section or abdominal surgery from 7 normal non-pregnant women, 7 women with normal pregnancies, and 7 women with preeclampsia. 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% to 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 non-pregnant 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) A significantly greater number of neutrophils adhered to endothelium and infiltrated into the intimal space in the maternal systemic vasculature of preeclamptic women than in that of normal pregnant women or normal non-pregnant women; 2) No significant difference in lymphocyte infiltration was observed 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 women with preeclampsia.

Figure 1

Leukocyte infiltration into vessels of subcutaneous fat in normal nonpregnant (NNP), normal pregnant (NP) and preeclamptic (PE) women. Lymphocytes indicated by CD99 staining infiltrated approximately 20 – 30% of subcutaneous fat vessels with no significant differences among groups (panel a). Visual score of vessel infiltration was also not different among groups for CD99 (panel b). In contrast, neutrophil infiltration indicated by CD66b staining showed significant differences among groups. Preeclamptic women had a significantly higher percentage of vessels stained for CD66b than normal pregnant women which had a significantly higher percentage than normal nonpregnant women (panel c). The visual score for CD66b vessel staining was significantly higher for preeclamptic women than for normal pregnant or normal nonpregnant women. Monocyte/macrophages indicated by CD14 staining were observed in the fat tissue, but not in the vessels. Data represent mean ± SE. * P < 0.05, ** P < 0.01

Figure 2

Representative examples of leukocyte infiltration into vessels of subcutaneous fat in NNP, NP and PE women. Panel a, IgG negative control in a PE patient; panel b, CD 14 staining of macrophages in adipocytes of a NP patient; panel c, CD 14 staining in a PE patient; panel d, CD99 staining of lymphocytes in NNP patient; CD99 staining in a NP patient; CD99 staining in a PE patient; panel g, CD66b staining of neutrophils in a NNP patient; panel h, CD66b staining in a NP patient; panel i, CD66b staining in a PE patient. CD14 staining of monocytes/macrophages was not present in vessels, but was present in the adipocytes. CD99 staining of lymphocytes was present in vessels and in adipocytes (arrows, panels d-f), but there were few CD99 stained cells per vessel and there was no difference in the amount of staining among the groups. Only CD66b staining of neutrophils showed a significant difference with PE vessels showing significantly more staining than NP or NNP vessels. Panel i shows the lumen of a PE vessel almost completely lined with neutrophils adhered to endothelium (arrows). In contrast, when neutrophils were present in NP vessels, there were few neutrophils and they were usually present in the lumen and not adhered to endothelium (arrows, panel h). Panel g shows no CD66b staining in a NNP vessel. Brown color indicates specific staining of antigens. VL, vessel lumen; A, adipocyte. All images are 400X. Scale bar indicates 50 microns.