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A protein in blood serum that is a component of the innate immune system, acting as a positive regulator of the alternative pathway of the complement system.

[Probably pro- + Latin perdere, to destroy; see perdition + -in.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Medicine) immunol a protein present in blood serum that, acting with complement, is involved in the destruction of alien cells, such as bacteria
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
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The HLA class III region is formed by genes that code components of the complement pathway (C2, properdin, factor B, C4A, and C4B) and products with inflammatory activity such as TNF-[alpha] and acute phase proteins [25].
* Persons with persistent complement component deficiencies (including inherited or chronic deficiencies in C3, C5-C9, properdin, factor D, factor H, or who are taking eculizumab [Solaris]); persons with anatomic or functional asplenia (including sickle cell disease); microbiologists routinely exposed to isolates of Neisseria meningitidis; persons identified as at increased risk because of a serogroup B meningococcal disease outbreak.
In the alternative complement pathway, C3b reacts with the proteins factor B, adipsin, and properdin to compose C3 convertase.
The proteins involved in immunity and inflammation were complement C3 precursor (C3), complement factor H precursor (Cfh), complement component 4, gene 2 precursor (C4a), properdin precursor (Cfp), ficolin-1 precursor (Fcn1), complement component 6 (C6), complement component C8 gamma chain (C8g), complement component C8 beta chain (C8b), and beta-2-glycoprotein 1 precursor (ApoH).
[64.] Morrison DC, Kline LF (1977) Activation of the classical and properdin pathways of complement by bacterial lipopolysaccharides (LPS).
Moreover, tubular heparan sulfate proteoglycans provide a docking platform for activation of the alternative pathway of the complement cascade via properdin, which may play a role in proteinuric renal damage [32].
(10) This could be due to decreased serum immunoglobulin, protein deficiency, decreased bactericidal activity of the leukocytes, immunosuppressive therapy, decreased perfusion of the spleen caused by hypovolemia and loss in the urine of a complement factor (Properdin factor 3) that opsonizes certain bacteria.
Involvement of the classic and alternate (properdin) pathways for complement activation.
Plasma concentrations of major human complement components were determined by enzyme-linked immunoassays, including complement fragments C5a (Quidel Corporation, San Diego, CA), C3a (Quidel Corporation, San Diego, CA), Bb (Quidel Corporation, San Diego, CA), soluble C5b-9 (SC5b-9, Quidel Corporation, San Diego, CA), properdin (Uscnk Life Science Inc., Wuhan, China), and C3 (Quidel Corporation, San Diego, CA).
Stover, "The role of properdin in murine zymosan-induced arthritis," Molecular Immunology, vol.
The hyalinotic lesions are usually formed by nonspecific trapping of the high-molecular-weight circulating proteins, such as IgM and C1q, and these lesions must be distinguished from the immune-complex deposits seen in other forms of glomerular diseases, where additional components of the complement, that is, C3 and properdin, also display reactivity in these deposits.
Naked and poloxamine-coated nanoparticles in the mushroom and mushroom-brush conformation also activate the complement through the alternative pathway by covalent conjugation of properdin to poloxamine and the C3 component adsorption.