Objective: To analyse activation of maternal peripheral blood leukocytes by flow cytometric measurements of intracellular free-ionised calcium of lymphocytes, granulocytes and monocytes, separately.
Design: Case-control study.
Setting: High risk pregnancy service in a regional centre.
Material: Samples from 10 women with pre-eclampsia, 10 appropriately-matched women with normal pregnancy, nine multigravid normal women at mid-gestation selected as being least likely to demonstrate any tendencies towards pre-eclampsia, and 11 healthy nonpregnant women of reproductive age were studied.
Methods: Using flow cytometry, intracellular free ionised calcium ([Ca2+]i) was estimated by loading the cells with Fluo-3 and measuring the changes in fluorescence intensity induced by free ionised calcium. After the basal levels were measured, the response of phagocytes to stimulation with n-formylmethionyl-leucyl-phenylalanine (fMLP) was determined.
Main outcome measures: Basal [Ca2+]i of peripheral blood leukocytes.
Results: Median basal [Ca2+]i was significantly increased in all three subsets of leukocytes--lymphocytes, granulocytes and monocytes in pre-eclampsia--compared with the three control groups. Samples from both groups of women with normal pregnancy did not differ from those from nonpregnant women. The peak responses of monocytes to stimulation with 10 nmol fMLP were greater in samples from pre-eclamptic women, giving evidence of priming.
Conclusions: Peripheral blood leukocytes are activated in pre-eclampsia in terms of basal changes in the intracellular second messenger--free ionised calcium. Peripheral blood monocytes are primed to give greater responses after stimulation with fMLP.