Which blood group systems' antibodies exhibit dosage effects?

The blood group system that exhibits dosage effects in its antibodies is the Duffy blood group system. Dosage effects occur when the strength of an antibody reaction is influenced by the presence of one or two copies of an antigen on the red blood cells. In the case of Duffy antibodies, the reactions are stronger when the target cells have homozygous expression of the antigen, meaning that both alleles at the Duffy locus express the antigen. This means that if an individual has two copies of the Duffy antigen, the reaction with the corresponding antibody will be more pronounced compared to individuals with only one copy or those lacking the antigen altogether.

The other blood group systems mentioned, such as ABO, Rh, and Kell, do not typically demonstrate this dosage effect in the same way. For example, while Rh antibodies may show varying intensities depending on the genotype of the red cells, they do not exhibit the clear-cut dosage effects that are characteristic of the Duffy system. Understanding these nuances is critical for immunohematology, particularly in the context of blood transfusion and hemolytic disease of the newborn.