Lymphocyte subsets and mitogen stimulation of blood lymphocytes in preeclampsia

The question of whether there are differences in systemic immune reactivity in severe preeclampsia compared with normal pregnancy was addressed.

During the third trimester, blood samples were taken from 12 pregnant women with severe preeclampsia. Five of the preeclamptic pregnancies were analyzed separately because they were treated with dexamethasone before the blood samples were taken. The seven dexamethasone-treated preeclamptic pregnant women were analyzed and compared with six uncomplicated pregnancies. A control group consisted of 15 nonpregnant females. Lymphocyte subsets were identified by flow cytometry. The function of peripheral blood mononuclear cells (PBMCs) was studied as proliferative responses to mitogens alone and in combination with immunomodulating drugs.

An increased number of B lymphocytes (CD19+) (P < 0.05) and natural killer (NK) cells (P < 0.05) was noticed in severe preeclampsia compared with normal pregnancy. The proliferative response of PBMCs in phytohemagglutinin (PHA)-stimulated cultures in autologous serum from patients with severe preeclampsia was reduced (P < 0.05) compared with normal pregnancy. The addition of indomethacin and cimetidine significantly stimulated (P < 0.05) the proliferative responses. The enhancing effect of cimetidine was not found in dexamethasone-treated preeclamptic patients.

The presence of systemic immunosuppression in severe preeclampsia is demonstrated as a reduced proliferative response of PBMCs to PHA, which could be partly restituted by indomethacin or cimetidine, indicating immunosuppressor activity that is mediated by prostaglandin and histamine. Increased levels of B lymphocytes and NK cells were also noticed.