There are four major blood groups determined by the presence or absence of two antigens – A and B – on the surface of red blood cells In addition to the A and B antigens, there is a protein called the Rh factor, which can be either present () or absent (–), creating the 8 most common blood types (A, A, B, B, O, O, AB, AB)Any ABO type component may be used Rh Compatibility ONLY APPLIES TO RED BLOOD CELLS AND PLATELETSFollowing the ABO system, the Rh system is the most recognized and clinically significant blood group system The five primary Rh antigens (D, C, c, E, and e) represent most of the clinically significant antibodies in the Rh system, and the D antigen is the most immunogenic antigen outside of the ABO system Blood Groups What is blood type and rh