Role of placental alkaline phosphatase in the internalization of trypomatigotes of Trypanosoma cruzi into HEp2 cells

BACKGROUND In vitro, Trypanosoma cruzi invades a wide variety of mammalian cells by an unique process that is still poorly understood. Trypomastigotes adhere to specific receptors on the outer membrane of host cells before intracellular invasion, causing calcium ion mobilization and rearrangement of host cell microfilaments. OBJECTIVE To test if placental alkaline phosphatase ( PLAP), a trophoblast plasma membrane protein anchored by a glycosylphosphatidylinositol molecule, is involved in the transplacental transmission of this parasite. METHOD We cultured HEp2 cells with the parasite and studied PLAP and actin microfilaments. The results were correlated with invasion rate. RESULTS Human HEp2 tumour cells express PLAP. HEp2 cells infected with trypomastigotes showed alteration in their alkaline phosphatase activity and a different pattern of actin organization, compared to control cells. Perturbation of PLAP from HEp2 cells before infection with T. cruzi trypomastigotes decreased the invasion rate. CONCLUSION Placental alkaline phosphatase could be involved in the internalization of T. cruzi into HEp2 cells, via activation of tyrosine kinase and rearrangement of actin microfilaments.