title: Electron microscopical investigation of surface alterations on Giardia lamblia trophozoites after exposure to a cytotoxic monoclonal antibody.
abstract: The present study describes a transmission electron microscopical investigation of trophozoites from Giardia lamblia clone GS/M-83-H7 after exposure to monoclonal antibody (MAb) G10/4. From previous studies it is known that this antibody immunoreacts with the parasite's major surface antigen VSP (variable surface protein) and exhibits a complement-independent cytotoxic effect on trophozoites of clone GS/M-83-H7. Our investigations revealed that cytotoxicity of MAb G10/4 is associated with shedding of VSP-containing membrane vesicles from the parasite surface and a concomitant partial disruption of the cellular membrane. These morphological alterations depend on the cross-linking capacity of the antibody because the immunoreactivity of respective monovalent F(ab)' has no significant influence on the cell-surface structure. These findings indicate that the membrane-disintegrative activity of MAb G10/4 may be responsible for the parasitocidal function of the antibody.
authors.affiliation: Institute of Parsitology, University of Berne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Hemphill
authors.forename: S
authors.initials: S
authors.lastname: Stäger
authors.forename: B
authors.initials: B
authors.lastname: Gottstein
authors.forename: N
authors.initials: N
authors.lastname: Müller
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D000913:Antibodies, Protozoan / Q000276:immunology* / Q000494:pharmacology; D000953:Antigens, Protozoan / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology*; D002462:Cell Membrane / Q000648:ultrastructure; D016829:Giardia lamblia / Q000276:immunology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D015800:Protozoan Proteins
chemical_list: D000911:Antibodies, Monoclonal; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000954:Antigens, Surface; D015800:Protozoan Proteins; C072464:variant surface protein H7, Giardia lamblia