title: Invasion of Rh Null Cells by Plasmodium falciparum identifies a new invasion pathway.
abstract: The malaria parasite, Plasmodium falciparum, invades the human erythrocyte through a complex interaction with erythrocyte receptors characterized by patterns of resistance to various enzymes. As invasion rates are influenced by blood group polymorphisms, we reasoned that the extremely rare rhesus null (Rh(null)) erythrocytes could be informative in characterizing receptors. The aim was to test whether the complete absence of the Rh complex from the cell membrane impacted on parasite invasion. Enzyme treatment patterns for four P. falciparum isolates were first characterised for normal Rh cells. Two isolates showed an enzyme treatment pattern not hitherto described, with resistance to neuraminidase, trypsin and chymotrypsin. In contrast, all isolates had enhanced invasion rates for the Rh(null) cell for all enzyme treatment regimens. The first finding suggests there is another pathway that P. falciparum can utilise to invade the host. We speculate that the Rh null cell membrane exposes a novel ligand defined as Receptor N.
authors.affiliation: Division of Infectious Diseases and Immunology, The Australian Centre for International and Tropical Health and Nutrition, The Queensland Institute of Medical Research, Herston Brisbane, 4006, Australia.
authors.forename: Wendy Y
authors.initials: WY
authors.lastname: Chung
authors.forename: Donald L
authors.initials: DL
authors.lastname: Gardiner
authors.forename: Catharine
authors.initials: C
authors.lastname: Hyland
authors.forename: Katharine R
authors.initials: KR
authors.lastname: Trenholme
mesh_terms: D000818:Animals; D002918:Chymotrypsin / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000378:metabolism / Q000469:parasitology; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology*; D006790:Host-Parasite Interactions; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood* / Q000469:parasitology; D009439:Neuraminidase / Q000378:metabolism; D010963:Plasmodium falciparum / Q000472:pathogenicity* / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D012204:Rh-Hr Blood-Group System / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism
chemical_list: D011956:Receptors, Cell Surface; D012204:Rh-Hr Blood-Group System; D009439:Neuraminidase; D002918:Chymotrypsin; D014357:Trypsin