Hyoid Bone Anatomy
Rh antigens: definition and blood types
Rh Blood Group System:
Rh antigens (= agglutinogens) are one of many types of surface marker molecules made by red blood cells.
Anitgenic surface markers.
- The letters Rh are applied to these antigens because they were first identified by Landsteiner and Wiener in 1940 using antibodies against Rhesus monkey RBCs.
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- Chemically, Rh antigens are part of long proteins that coil back and forth through the RBC plasma membrane, forming six extracellular loops.
- The sequence of amino acids on extracellular loops 3, 4, and 6 determines the Rh antigen type.
Extracellular loops 3, 4, and 6 highlighted
- Over 40 types of Rh antigens have been identified thus far, each differing in structure by just a few amino acids.
- Most common are the D antigens, and individuals who have these antigens are considered to be Rh+.
- About 85% of Caucasians, 90%-95% of African Americans and 98%-99% of Asian Americans are Rh+.
- Individuals who have other types of Rh antigens are considered to be Rh-.
Review the Rh blood group system.