title: Enhanced complement susceptibility of avidin-biotin-treated human erythrocytes is a consequence of neutralization of the complement regulators CD59 and decay accelerating factor.
abstract: Biotinylation of erythrocytes (E) followed by avidin cross-linking at specific sites has been suggested as a novel means of drug delivery. Upon avidin cross-linking, biotinylated E become complement-activating and highly susceptible to complement lysis, thus bringing about release of entrapped drug. We set out to examine the mechanisms of this biotin-avidin-induced lytic susceptibility, focusing on the effects of biotinylation and avidin cross-linking on the major E complement regulatory molecules, decay accelerating factor (DAF) and CD59. We demonstrate here that biotinylation of E, which does not render them complement activating, partially inhibits DAF but has little effect on CD59. Subsequent cross-linking with avidin causes complete inhibition of DAF and near complete loss of CD59 activity. Following cross-linking, DAF and CD59 become associated in high molecular mass avidin-containing complexes on the membrane. Incorporation of physiological amounts of CD59 into the membranes of biotinylated and avidin cross-linked E is sufficient to render these cells resistant to complement lysis whereas incorporation of DAF has relatively little effect. An understanding of the molecular mechanisms underlying complement susceptibility of biotin-avidin treated E should allow a rational design of strategies for drug delivery using E or other large, potentially complement-activating carriers.
authors.affiliation: Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff, U.K.
authors.forename: A B
authors.initials: AB
authors.lastname: Zaltzman
authors.forename: C W
authors.initials: CW
authors.lastname: Van den Berg
authors.forename: V R
authors.initials: VR
authors.lastname: Muzykantov
authors.forename: B P
authors.initials: BP
authors.lastname: Morgan
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000187:drug effects* / Q000494:pharmacology / Q000502:physiology*; D001360:Avidin / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D001710:Biotin / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D018958:CD55 Antigens; D018957:CD59 Antigens; D003167:Complement Activation; D003169:Complement Inactivator Proteins / Q000187:drug effects* / Q000494:pharmacology / Q000502:physiology*; D004337:Drug Carriers; D004912:Erythrocytes / Q000187:drug effects* / Q000276:immunology / Q000502:physiology*; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D008562:Membrane Glycoproteins / Q000187:drug effects* / Q000494:pharmacology / Q000502:physiology*; D009500:Neutralization Tests
chemical_list: D000906:Antibodies; D015703:Antigens, CD; D018958:CD55 Antigens; D018957:CD59 Antigens; D003169:Complement Inactivator Proteins; D004337:Drug Carriers; D008562:Membrane Glycoproteins; D001360:Avidin; D001710:Biotin