@article {4486,
	title = {Clq binding to liposomes is surface charge dependent and is inhibited by peptides consisting of residues 14-26 of the human ClqA chain in a sequence independent manner},
	journal = {Biochimica Et Biophysica Acta-Biomembranes},
	volume = {1418},
	number = {1},
	year = {1999},
	note = {ISI Document Delivery No.: 189EWTimes Cited: 20Cited Reference Count: 36},
	month = {Apr},
	pages = {19-30},
	type = {Article},
	abstract = {Complement activation by anionic liposomes proceeds by antibody-independent, C1q-initiated activation of the classical pathway. Purified C1q bound to anionic liposomes in an acidic lipid concentration-dependent manner. Saturation binding, but not the apparent association constant, was enhanced by increasing the cardiolipin content of the liposomes or decreasing either the pH or ionic strength of the reaction mixture. These observations indicate the involvement of electrostatic factors in the binding. A highly cationic region in the collagen-like domain of C1q comprised of residues 14-26 of the C1qA polypeptide chain was assessed for involvement in liposome binding. This region has previously been shown to mediate C1q binding to other immunoglobulin-independent activators of the classical pathway of complement. Peptides containing residues 14-26 of C1qA, denoted C1qA(14-26), inhibited C1q binding to and complement activation by anionic liposomes. The inhibitory capacity of these cationic peptides had no sequence or conformation specificity. Rather, the amount of positive charge on the peptides was the determining factor. When present in excess, peptides with five cationic residues inhibited C1q binding and complement activation; however, C1q peptides with only two cationic residues did not. In addition to the C1qA(14-26) region, other parts of C1q that contain cationic residues may also be involved in C1q binding to anionic liposomes. (C) 1999 Elsevier Science B.V. All rights reserved.},
	keywords = {1ST, ACTIVATES COMPLEMENT, C1Q A-CHAIN, CLASSICAL COMPLEMENT PATHWAY, CLEARANCE, Clq binding, COLLAGEN, COMPONENT, liposome clearance, liposome-mediated complement activation, PHAGOCYTOSIS, PROTEINS, SERUM, SYSTEM},
	isbn = {0005-2736},
	url = {<Go to ISI>://000079892300002},
	author = {Bradley, A. J. and Brooks, D. E. and Norris-Jones, R. and Devine, D. V.}
}
@article {4210,
	title = {Inhibition of liposome-induced complement activation by incorporated poly(ethylene glycol) lipids},
	journal = {Archives of Biochemistry and Biophysics},
	volume = {357},
	number = {2},
	year = {1998},
	note = {ISI Document Delivery No.: 119UCTimes Cited: 65Cited Reference Count: 50},
	month = {Sep},
	pages = {185-194},
	type = {Article},
	abstract = {Complement activation causes opsonization of foreign particles leading to particle elimination from the blood. Complement-mediated opsonization of charged and large liposomes presents a fundamental problem in their use to deliver therapeutic agents in vivo. To prolong the circulation half-lives of such liposomes, complement activation must be curtailed. The aim of this study was to assess the ability of poly(ethylene glycol)-lipids (PEG-lipids) to inhibit the in vitro activation of the classical pathway of complement in human serum by anionic liposomes. Incorporation of cholesterol-PEG(600) (CH-PEG(600)), cholesterol-PEG(1000) (CH-PEG(1000)), or phosphatidylethanolamine-PEG(2000) (PE-PEG(2000)) resulted in dose-dependent inhibition of Clq binding and complement activation. The dose of PEG-lipid at which complement activation was blocked was inversely related to the PEG chain length. Complement activation was strongly inhibited when 15 mole\% of CH-PEG(600), 10 mole\% CH-PEG(1000), or 5 mole\% PE-PEG(2000), was incorporated into 100-nm anionic liposomes. PEG-lipid incorporation into larger liposomes (240 nm) was also successful in blocking C1q binding and complement activation. Radiolabeled cholesterol-PEG(similar to 1400) was prepared and used to determine both the percentage of CH-PEG incorporated into the liposomes and the percentage maintained in the liposomes in the presence of 50\% human serum at 37 degrees C for up to 24 h. (C) 1998 Academic Press.},
	keywords = {C1q, CHOLESTEROL, CLEARANCE, complement activation, HEPATIC-UPTAKE, INVIVO, LARGE UNILAMELLAR VESICLES, LIPOSOMES, POLY(ETHYLENE GLYCOL), POLYETHYLENE-GLYCOL, PROLONGED CIRCULATION TIME, SERUM, SIZE, SURFACE-CHARGE},
	isbn = {0003-9861},
	url = {<Go to ISI>://000075915200002},
	author = {Bradley, A. J. and Devine, D. V. and Ansell, S. M. and Janzen, J. and Brooks, D. E.}
}
