Complement Resistance of Parasites

Jokiranta, T. Sakari; Jokipii, Liisa; Meri, Seppo

doi:10.1111/j.1365-3083.1995.tb03620.x

Cited by 41 publications

(43 citation statements)

References 88 publications

(77 reference statements)

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“…1). These strategies are beyond the scope of this review, and are well reviewed elsewhere [53][54]. However, locally synthesized C and expression of C receptors in the tissues may be important factors in enabling microorganisms to successfully colonize tissues.…”

Section: Hijacking Of C By Microorganismsmentioning

confidence: 99%

Extrahepatic complement biosynthesis: where, when and why?

Morgan

Gasque

1997

Clinical and Experimental Immunology

304

220

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Section: Hijacking Of C By Microorganismsmentioning

confidence: 99%

Extrahepatic complement biosynthesis: where, when and why?

Morgan

Gasque

1997

Clinical and Experimental Immunology

304

220

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“…Endogenous regulators exist to prevent pathology associated with unconfined or inadvertent complement activation (4,5). Successful pathogens have developed several mechanisms to evade the host complement system (1,6,7). In several of these evasion mechanisms, pathogens may recruit host complement regulatory molecules to their own surface or produce inhibitors of complement activation, which are either secreted or remain associated with their surfaces (1, 6 -8).…”

mentioning

confidence: 99%

Purification, Cloning, and Expression of a Novel Salivary Anticomplement Protein from the Tick, Ixodes scapularis

Valenzuela¹,

Charlab²,

Mather³

et al. 2000

Journal of Biological Chemistry

224

219

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The alternative pathway of complement is an important defense against pathogens and in tick rejection reactions. The tick Ixodes scapularis is able to feed repeatedly on its natural host and has a salivary anticomplement activity that presumably facilitates feeding. In this study, we purified and then obtained the aminoterminal sequence of the I. scapularis salivary anticomplement (Isac). We found a full-length clone coding for Isac by random screening of a salivary gland cDNA library. Expressing Isac cDNA in COS cells reproduced the activity found in tick saliva, namely, inhibition of rabbit erythrocyte lysis by human serum in the presence of Mg 2؉ and EGTA, inhibition of C3b binding to agarose in the presence of Mg 2؉ and EGTA, and acceleration of factor Bb uncoupling from the C3 convertase generated by the alternative pathway. Recombinant Isac had no effect on the recalcification time of human platelet-poor plasma or in the classical complement pathway, indicating that it is a specific inhibitor similar to the regulators of complement activation of the alternative pathway such as factor H. Isac, however, has no similarity to any protein in the GenBank TM data base, indicating that it is a novel and relatively small (18.5 kDa) anticomplement molecule.

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“…The behavior of biotinylated and unlabeled C1q toward immobilized IgG was identical in our binding assays. In contrast, biotinylation of IgG has been shown to abrogate the binding of C1q and activation of the classical pathway of complement (35). Therefore, it appears that (free and accessible) lysine residues of IgG but not of C1q play a role in the interaction of both proteins.…”

Section: Discussionmentioning

confidence: 85%

Dissection of C1q Capability of Interacting with IgG

Kaul

Loos

1997

Journal of Biological Chemistry

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C1q-bearing immune complexes have been observed in diseases such as rheumatoid arthritis and human immunodeficiency virus infection-associated neuropathy. For the purpose of understanding better the phenomenon of C1q-bearing immune complexes, we investigated the constancy of the C1q-IgG interaction. An enzyme-linked immunosorbent assay was developed in which wells were coated with IgG to mimic antigencomplexed IgG. Serial dilutions of C1q were applied for distinct time intervals, and bound C1q was detected either directly or after exposure to one of several elution buffers. Our results show that a part of C1q attached to IgG forms a tight association that is not reversible under treatment with buffers containing usually protein-protein interaction-dissociating reagents such as 3 M NaCl, 5 M urea, sodium dodecyl sulfate, or ␤-mercaptoethanol. The formation of the highly stable C1q-IgG complex was found to be time-, temperature-, and pH-dependent and to proceed with bound C1q even in the absence of free C1q in the supernatant. In ligand blotting experiments we demonstrate for the first time directly that all three chains of C1q can individually bind IgG. Altogether, our results provide a suitable explanation for the formation and persistence of C1q-bearing immune complexes.

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Complement Resistance of Parasites

Cited by 41 publications

References 88 publications

Extrahepatic complement biosynthesis: where, when and why?

Extrahepatic complement biosynthesis: where, when and why?

Purification, Cloning, and Expression of a Novel Salivary Anticomplement Protein from the Tick, Ixodes scapularis

Dissection of C1q Capability of Interacting with IgG

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