title: Iron mediates Trichomonas vaginalis resistance to complement lysis.
abstract: Trichomonas vaginalis, a sexually transmitted disease agent in humans, is readily lysed by activation of the alternative complement pathway. The parasite became resistant following growth in medium supplemented by iron compared to parasites grown in medium depleted of iron, which were readily killed by complement. The resistance to complement was dependent on iron concentration while divalent cations other than iron were ineffective, showing specific regulation of this property by iron. Lactoferrin, but not transferrin, rendered low-iron-parasites resistant to complement lysis, reinforcing the in vivo modulation by a known source of iron for this parasite. Pretreatment of high-iron, complement-resistant parasites with proteinase inhibitors resulted in lysis by complement, indicating that resistance was likely due to proteinase degradation of C3 on the trichomonal surface.
authors.affiliation: Department of Microbiology, University of Texas Health Science Center, San Antonio 78284-7758, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Alderete
authors.forename: D
authors.initials: D
authors.lastname: Provenzano
authors.forename: M W
authors.initials: MW
authors.lastname: Lehker
mesh_terms: D000818:Animals; D003176:Complement C3 / Q000276:immunology*; D003546:Cysteine Endopeptidases / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism*; D014246:Trichomonas vaginalis / Q000276:immunology* / Q000378:metabolism / Q000472:pathogenicity
chemical_list: D003176:Complement C3; D007501:Iron; D003546:Cysteine Endopeptidases