Immunoglobulin complex deposits in Plasmodium falciparum-infected placentas from Malawi and Papua New Guinea.

Term placentas from 35 patients infected with Plasmodium falciparum were obtained in Malawi in southeast Africa and six term placentas from patients infected with P. falciparum were obtained in Wewak, Papua New Guinea, Melanesia. The placental tissues were examined by light microscopy and by an immunohistologic method to compare the pathologic changes of placentas in the two malaria-endemic countries. Using the number of parasitized red blood cells (PRBC) in intervillous spaces, pregnant women from Malawi with placental parasitemia were categorized into three groups. In the high PRBC group (> 20%, group I), there was no deposition of IgE in fetal blood vessels. In contrast, IgE was observed in fetal blood vessels of the intermediate PRBC group (1-10%, group II) and low PRBC group (< 1%, group III). In all six placentas from Papua New Guinean women, deposition of immune complexes, including IgE, was observed in the fetal blood vessels. All placentas with deposition of IgE in fetal blood vessels showed no sequestration of malaria parasites in intervillous spaces. Our data indicate that the amount of deposition of IgE in the placenta from women infected with P. falciparum is inversely correlated with the degree of parasitemia at that site.