Low-incidence antigens are antigens that occur in less than 1% of the population.
Antibodies to low-incidence antigens
- Low-incidence antigens are not usually found on screen cell and antibody panels.
- Antibodies are hard to test for, but it is usually not difficult to find compatible blood.
- Suspect this antibody if an AHG crossmatch is incompatible and other causes have been ruled out, such as a positive donor DAT or ABO incompatibility.
- Examples of low-incidence antigens include: Cw, V, Kpa, Jsa.
- When going through the process of Ruling Out, antibodies like anti-V, anti-Cw, anti-Lua, anti-Kpa, and anti-Jsa usually fall into the "unable to rule out" category.
High-incidence antigens are antigens that occur in greater than 99% of the population.
Antibodies to high-incidence antigens
- Antibodies are rare and may be difficult to identify due to lack of negative panel cells for other high-incidence antigens (difficult to rule out).
- Reactions with screen and panel cells will all be positive (same strength and same phase).
- Auto control will be negative.
- Difficult to find antigen-negative compatible blood.
- Examples of antibodies to high-incidence antigens are: anti-k, anti-Kpb, anti-Jsb, and anti-Lub.
If an antibody to either a high- or low-incidence antigen is present, it may be difficult to identify and may require further testing in a reference blood bank.