Circulating immune complexes in hypertensive disorders of pregnancy.

Circulating immune complexes (CICs) were measured in sera of pregnant women with pre-eclampsia and other hypertensive disorders of pregnancy and pregnant women with renal disease, using four different CIC assays: platelet 125I-labelled staphylococcal protein A test ( PIPA ), conglutinin-binding ELISA, C1q-binding ELISA and rheumatoid factor binding inhibition ELISA. CICs were shown to be present in the sera of 47% of women with severe pre-eclampsia, in 20% with mild pre-eclampsia and in 18% of women with normal pregnancy using the PIPA test. The PIPA test was capable of discriminating between patients with renal disease, which were all positive, and women with uncomplicated hypertension, which were all negative. All patients positive in the PIPA test, and most patients with a positive RFbI -ELISA test, had various amounts of proteinuria. Although half of the women with severe pre-eclampsia showed the presence of CICs in the PIPA test, the amount of these complexes was low and not constant in serial samples from the same patient.