Expression of intercellular adhesion molecule 1 (ICAM-1) in Plasmodium falciparum-infected placenta

We investigated the expression of intercellular adhesion molecule 1 (ICAM-1 ) in malarial placenta and related histological changes. Thirty-two malaria l and 40 control term placentae were collected at Tanga, Tanzania and exami ned histologically and immunohistochemically. Malaria infected placentae we re further divided into acute (lj) and chronic (17) cases according to the presence of malarial pigment. The expression of ICAM-1 on monocyte, syncyti o- and cytotrophoblasts, endothelial and stromal cells was assessed. Birthw eight was lower and leukocyte counts higher in placentae with chronic infec tion. Many monocytes were present within the intervillous spaces, especiall y in placentae with chronic infection, and aggregated with parasitized eryt hrocytes. Some monocytes were adhesive to the surface of fibrinoid deposits . ICAM-1 expression on monocytes of malarial placentae was significantly co nspicuous and correlated to the degree of intervillous leukocyte infiltrati on. Syncytiotrophoblasts often did not show ICAM-1, even though ICAM-1 was expressed by endothelium and weakly by cytotrophoblasts and stromal cells i n both infected and control placentae. These results suggest that the expre ssion of ICAM-1 on monocytes contributes to sequestration of infected eryth rocytes within the intervillous spaces and their adhesion to fibrin masses and that ICAM-1 is unlikely to be associated with the direct adhesion of in fected erythrocytes to the syncytiotrophoblasts. (C) 2001 Harcourt Publishe rs Ltd.