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(prō`pərdən), protein found in the blood serum of humans and some of the higher animals that appears to participate in certain specific immune responses. It is associated with the engulfing of foreign particles and invading cells by phagocytes and with tissue inflammation (see bloodblood,
fluid pumped by the heart that circulates throughout the body via the arteries, veins, and capillaries (see circulatory system; heart). An adult male of average size normally has about 6 quarts (5.6 liters) of blood.
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; immunityimmunity,
ability of an organism to resist disease by identifying and destroying foreign substances or organisms. Although all animals have some immune capabilities, little is known about nonmammalian immunity.
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). Properdin has been isolated in highly purified form.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in mammals, a protein in blood serum, one of the globulins and one of the factors of natural immunity. Properdin participates in destroying bacteria and protozoans, neutralizing viruses, and stimulating phagocytosis either independently or by activating the complement system.

In man, properdin is a homogeneous protein detected electrophoretically in the beta-globulin region; its molecular weight is 223,000. In a healthy person, 1 milliliter of blood contains 2.5—8 micrograms of properdin nitrogen. Properdin content decreases with burns, after irradiation, and with malignant neoplasms; it increases with the introduction of bacterial endotoxins.

Properdin differs functionally and antigenetically from immunoglobulins and complement factors. It is a part of the properdin system, a special system of serum proteins that function together; the system was discovered in 1954 by the American scientist L. Pillemer and his colleagues. The properdin system includes properdin, factor A (a protein inactivated by hydrazine), factor B (a β-glycoprotein with an increased content of glycine), and an Mg2+ ion.


Chernokhvostova, E. V. “Sistema properdina.” In L. S. Reznikova, Komplement i ego znachenie v immunologicheskikh reaktsiiakh. Moscow, 1967. Pages 157–84.
“Properties of Highly Purified Human Properdin.” Journal of Immunology, 1968, vol. 100, no. 1.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A macroglobin of normal plasma capable of killing various bacteria and viruses in the presence of complement and magnesium ions.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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References in periodicals archive ?
Consistent with previous studies on plasma proteomes [11], our experiment confirmed that YCL treatment could decrease the expression of multiple complement components, including complement C3, complement C4, complement component C6, complement factor H precursor, properdin precursor, complement component C8 gamma chain, and complement component C8 beta chain.
There was no significant difference in properdin level between patients with scanty immune deposits lupus nephritis and immune complex deposits lupus nephritis (P = 0.357).
Association between combined properdin and mannose-binding lectin deficiency and infection with Neisseria meningitidis.
Properdin is a protein of the complement alternative pathway, which is a component of the normal host immune system.
The malarial sporozoites once injected in blood by the bite of female Anopheles mosquitoes are attached to hepatocytes through receptor for thrombospondin and properdin. (3) Liver dysfunction has been recognized in malaria infection (4) but information about geographical variation in urban Bangalore is scarce.
The regulators can be grouped into fluid-phase: factor H (f H) and properdin for alternative pathway, C1 inhibitor and C4b-binding protein (C4BP) for classical and MBL pathway; host cell membrane-bound: CR1, CR2, CD55, CD46, CD59; cell surface-attached complement regulators: fH, factor H-like protein 1 (FHL-1), C4BP and clusterin [200, 201].
* Children who have persistent complement component deficiencies (eg, C5-C9, properdin, factor H, or factor D); those traveling to (or residents of) countries where meningococcal disease is hyperendemic or epidemic; or those who are in a defined risk group during a community or institutional meningococcal outbreak.
Immunoglobulin (IgG, IgM, and IgA) and complement component (C3, C1q, C4, and properdin) full house deposits are observed by IF and granular dense deposits by EM, exclusively or predominantly in the mesangial areas (Figure 2).
(Beachwood, OH; 216-831-3200) under which Gliatech will use Abgenix' XenoMouse technology to generate fully human monoclonal antibodies to the complement protein properdin for use in the fields of cardiovascular and inflammatory diseases.
Persons who have persistent deficiencies (e.g., genetic deficiencies) in the complement pathway (e.g., C3, properdin, Factor D, Factor H, or C5-C9) have up to a 10,000-fold increased risk for meningococcal disease and can experience recurrent disease (16,17).
Children in relapse will have increased susceptibility to bacterial infection because of urinary losses of immunoglobulins and properdin factor B, defective cell mediated immunity, immunosuppressive therapy malnutrition and edema/ ascites acting as a potential "culture medium".