Which antigen is the primary marker for Rh typing due to its immunogenicity?

Which antigen is the primary marker for Rh typing due to its immunogenicity?

• A. C
• B. E
• C. D
• D. c

Answer: (C)

The D antigen is the primary marker for Rh typing because it is the most immunogenic of the Rh group. Its strong ability to elicit an antibody response means that exposure to D-positive red cells in someone who is D-negative commonly leads to anti-D formation, making D status the decisive factor in classifying someone as Rh positive or negative. This is why routine Rh typing centers on detecting D expression, and why Rh immune globulin is used to prevent alloimmunization in pregnancy. Other Rh antigens like C, E, and c exist and can be useful for extended antigen profiling, but they are less immunogenic and do not determine Rh status as reliably as D.

The D antigen is the primary marker for Rh typing because it is the most immunogenic of the Rh group. Its strong ability to elicit an antibody response means that exposure to D-positive red cells in someone who is D-negative commonly leads to anti-D formation, making D status the decisive factor in classifying someone as Rh positive or negative. This is why routine Rh typing centers on detecting D expression, and why Rh immune globulin is used to prevent alloimmunization in pregnancy. Other Rh antigens like C, E, and c exist and can be useful for extended antigen profiling, but they are less immunogenic and do not determine Rh status as reliably as D.