title: Cytoadherence of knobby and knobless Plasmodium falciparum-infected erythrocytes.
abstract: Cytoadherence of Plasmodium falciparum-infected erythrocytes to melanoma cells was analysed using strains or isolates of parasites expressing or not expressing knobs (K+ or K- phenotype) on the erythrocyte surface. Both K+ and K- parasites had the capacity to cytoadhere to melanoma cells. Using a panel of melanoma cell lines with different surface expression of the cytoadherence receptors CD36, thrombospondin and ICAM-1 indicated that CD36 was the major receptor for parasites of both K+ and K- phenotypes. Binding competition experiments between K+ and K- -infected erythrocytes suggested that K+ cytoadherence is of higher affinity than that of K- parasites. However, some K- cytoadherence was also found in isolates containing mixed populations of K+ and K- parasites. The interaction of the two types of infected erythrocytes with melanoma cells also differed ultrastructurally, erythrocytes of K+ phenotype showing intimate interdigitations with microvilli on the melanoma cells, while erythrocytes of K- phenotype displayed more separated interactions with fewer sites of contact and involving only a few melanoma cell microvilli. One and the same infected erythrocyte may co-express the ligand for CD36-mediated cytoadherence and the structures mediating binding of uninfected erythrocytes to form rosettes.
authors.affiliation: Department of Immunology, Stockholm University, Sweden.
authors.forename: W
authors.initials: W
authors.lastname: Ruangjirachuporn
authors.forename: B A
authors.initials: BA
authors.lastname: Afzelius
authors.forename: S
authors.initials: S
authors.lastname: Paulie
authors.forename: M
authors.initials: M
authors.lastname: Wahlgren
authors.forename: K
authors.initials: K
authors.lastname: Berzins
authors.forename: P
authors.initials: P
authors.lastname: Perlmann
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002448:Cell Adhesion; D002460:Cell Line; D004727:Endothelium / Q000166:cytology; D004912:Erythrocytes / Q000166:cytology / Q000469:parasitology* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D006801:Humans; D008545:Melanoma; D008854:Microscopy, Electron; D008871:Microvilli / Q000648:ultrastructure; D010963:Plasmodium falciparum / Q000502:physiology* / Q000648:ultrastructure; D012397:Rosette Formation; D014407:Tumor Cells, Cultured