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Rh factor
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Besides the markers of the ABO system, the red blood cell carries another family of markers: the Rh factor. These are antigens that are part of proteins embedded in the membrane, the cell's outer covering. Think of a second label, different from the ABO one.
The system has more than fifty antigens, but five matter more than the rest: D, C, c, E and e.
What matters is that these antigens are highly immunogenic, meaning the body reacts against them easily. If a person lacks the D antigen and is exposed to it, through a transfusion or a pregnancy, they can make anti-D antibodies, the defense proteins aimed at that exact marker.
Oddly enough, what these antigens are for is still unknown. They are thought to play a part in membrane stability.
In brief
The Rh factor is a group of antigens that are part of proteins in the red blood cell membrane.
A second label on the red blood cell, different from the ABO one.
Of its more than fifty antigens, the five most important are D, C, c, E and e.
They are highly immunogenic: someone who lacks the D antigen and is exposed to it in a transfusion or a pregnancy can form anti-D antibodies.
Its function is unknown; it may have to do with membrane stability.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingRh Blood Group System, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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