Expression of receptors for tumor necrosis factor in human placenta at term

The biological effects of tumor necrosis factor (TNF) are mediated through its interaction with high affinity receptors on target cells. Secretion of soluble cytokine receptors has been suggested as a mechanism of regulating cytokine activity in vivo. In a previous study we detected soluble TNF receptors (TNFRs) in amniotic fluid and urine samples from pregnant women, suggesting that secretion of soluble TNFRs may provide a mechanism for protection of the fetus against TNF action during pregnancy. In the present study, TNFR containing cells in cryostat sections from normal placentas at term were evaluated by monoclonal antibodies against the 55 kD--and the 75 kD TNFR in an indirect immunofluorescence technique. The 55 kD TNFR was expressed by the villous syncytiotrophoblasts, by vascular endothelial cells, by some decidual cells and by occasional cells in the placental stroma. Staining for the 75 kD TNFR was confined to the vascular endothelial cells, a relatively small number of stromal cells and decidual cells, whereas the villous syncytiotrophoblasts were negative. The abundant expression of TNFRs in placental tissue suggests: 1. That a considerable number of the placental cells are receptive to the regulatory activities of TNF; 2. That placental cells may be the cellular origin of soluble TNFRs secreted during pregnancy.