Rh Antibodies
Rh antibodies are IgG antibodies which are acquired through exposure to Rh-positive blood (generally either through pregnancy or transfusion of blood products). The D antigen is the most immunogenic of all the non-ABO antigens. Approximately 80% of individuals who are D-negative and exposed to a single D-positive unit will produce an anti-D antibody. The percentage of alloimmunization is significantly reduced in patients who are actively exsanguinating (some say to approx 15%)
All Rh antibodies except D display dosage (antibody reacts more stongly with red cells homozygous for an antigen than cells heterozygous for the antigen (EE stronger reaction vs Ee).
Rh antibodies are capable of causing hemolytic transfusion reactions with extravascular hemolysis. They may also result in severe hemolytic disease of the fetus and newborn (HDFN or HDN).
If anti-E is detected, the presence of anti-c should be strongly suspected (due to combined genetic inheritance). It is therefore common to select c-negative and E-negative blood for transfusion patients who have an anti-E. Anti-c is a common cause of delayed hemolytic transfusion reactions.
Read more about this topic: Rh Blood Group System