Properdin

properdin

[′prō·pər·dən]

(immunology)

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.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Properdin

 

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.

REFERENCES

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.

A. N. MATS

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