['It has been reported that T-helper (Th) 2 dominance in normal pregnancy shifts to Th1 dominance in preeclampsia. Peripheral blood mononuclear cell (PBMC) production of interleukin (IL)-12, which induce Th1 responses, has not been compared between these clinical states.', 'Peripheral blood mononuclear cell from 35 non-pregnant women, 35 healthy pregnant women, 12 mildly preeclamptic patients, and 15 severely preeclamptic patients were cultured for 24 hr. IL-12 secretion was determined by enzyme-linked immunosorbent assay (ELISA). Th1/Th2 ratios in PBMC were determined flow-cytometrically, and the amounts of HLA-DR and CD14 expression on the monocytes were obtained by flow cytometry.', 'Peripheral blood mononuclear cell from healthy pregnant subjects secreted less IL-12 than non-pregnant women. PBMC from severely preeclamptic patients secreted more IL-12 than those from healthy pregnant subjects, while IL-12 secretion in mild preeclampsia resembled secretion in normal pregnancy. Th1/Th2 ratios correlated were positively with IL-12. Increased HLA-DR antigens and reduced CD14 expression, suggesting monocyte activation, were observed in preeclamptic patients, although monocyte counts were unchanged.'] Is interleukin-12 secretion by peripheral blood mononuclear cells decreased in normal pregnant subjects and increased in preeclamptic patients?