Rh factor

Rh factor

an agglutinogen commonly found in human blood: it may cause a haemolytic reaction, esp during pregnancy or following transfusion of blood that does not contain this agglutinogen

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

Rh factor

[¦är′āch ‚fak·tər]

(immunology)

Any of several red blood cell antigens originally identified in the blood of rhesus monkeys. Also known as Rh antigen; rhesus factor.

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 It might be outdated or ideologically biased.

Rh Factor

 

(also rhesus factor), an antigen contained in the red blood cells of 85 percent of all persons and in the red blood cells of rhesus monkeys (Macacus rhesus). The Rh factor was discovered in 1940 by the Austrian scientists K. Landsteiner and A. Wiener. The blood of persons whose red blood cells contain the Rh factor is called Rh-positive. There are several different antigens in the Rh-factor system, including the Hr group, which together with Rh makes up the total Rh-Hr system. This system includes three varieties of Rh agglutinogen (D, C, and E), three varieties of Hr agglutinogen (c, d, and e), and other less common variants. Hr agglutinogen is contained in the red blood cells of 83 percent of all human beings. The Rh factor is transmitted by heredity as a dominant character and does not change throughout life (seeHEREDITY).

Determination of the Rh-factor and the blood group is obligatory for blood transfusion. When a person is injected parenterally with any agglutinogen of the Rh-Hr system that is absent from his blood, specific antibodies are elaborated. With repeated injection of that antigen, an “antigen-antibody” reaction occurs that produces functional bodily disturbances. Thus, if Rh-positive blood is transfused to an Rh-negative recipient who already has an antibody to Rh, such reactions as chills, fever, and short-term pains in the loin may occur. Severe cases may involve massive hemolysis with renal insufficiency. A distinctive feature of Rh transfusion reactions is their late manifestation—one or two hours after the transfusion. Treatment of these reactions involves venesection, followed by infusion of Rh-negative blood.

When an Rh-negative woman is pregnant with an Rh-positive fetus, she may become isoimmunized. Antibodies formed with repeated pregnancies may lead to an undeveloped pregnancy or intrauterine death of the fetus with subsequent involuntary abortion. If the infant is born alive, it may suffer from erythroblastosis fatalis.

Rh incompatibility develops no earlier than the seventh or eighth week of pregnancy, when hematopoiesis occurs in the embryo. Prophylaxis against Rh incompatibility is injection of anti-Rh gamma globulin.

REFERENCES

Solov’eva, T. G. Rezus-faktor i ego znachenie v klinicheskoi praktike, 2nd ed. Leningrad, 1963.
Kassirskii, I. A., and G. A. Akleseev. Klinicheskaia gematologiia, 4th ed. Moscow, 1970.
Grishchenko, I. I., and V. A. Shileiko. Izoimmunizatsiia k rezus-faktoru u beremennykh. Kiev, 1971.
Persianinov, L. S. “Nesovmestimost’ krovi materi i ploda.” In his book Akusherskii seminar, 2nd ed., vol. 2. Tashkent, 1973.

V. A. FROLOV

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