Which antibodies show dosage?

Master the CAMLPR Transfusion Test with interactive questions and detailed explanations. Boost your knowledge and ensure you're exam-ready with comprehensive study resources!

Multiple Choice

Which antibodies show dosage?

Dosage is the tendency of some antibodies to react more strongly with red cells that have two copies of the target antigen (homozygous) than with cells that have only one copy (heterozygous). This happens because antigen density on the red cell surface is higher when there are two copies, making antibody binding and agglutination more pronounced. The antibodies that typically show this dosage effect include those from the Kidd, Duffy, Rh, and MNSs systems. For example, anti-Jka often shows stronger reactions with Jka/Jka cells than with Jka/Jkb cells; anti-Fya or anti-Fyb can be more reactive with cells homozygous for the corresponding Duffy antigen; and many Rh and MNSs antibodies display stronger reactivity when the target antigen is present in two copies. Recognizing dosage helps in identifying antibodies and in selecting compatible donor units, since testing with homozygous antigen-bearing cells can reveal or confirm the antibody. ABO antibodies are usually IgM and react strongly regardless of zygosity, and Lewis antibodies are typically IgM with reactivity influenced more by secretor status than by dosage, so they’re not the classic examples of dosage.

Dosage is the tendency of some antibodies to react more strongly with red cells that have two copies of the target antigen (homozygous) than with cells that have only one copy (heterozygous). This happens because antigen density on the red cell surface is higher when there are two copies, making antibody binding and agglutination more pronounced.

The antibodies that typically show this dosage effect include those from the Kidd, Duffy, Rh, and MNSs systems. For example, anti-Jka often shows stronger reactions with Jka/Jka cells than with Jka/Jkb cells; anti-Fya or anti-Fyb can be more reactive with cells homozygous for the corresponding Duffy antigen; and many Rh and MNSs antibodies display stronger reactivity when the target antigen is present in two copies. Recognizing dosage helps in identifying antibodies and in selecting compatible donor units, since testing with homozygous antigen-bearing cells can reveal or confirm the antibody.

ABO antibodies are usually IgM and react strongly regardless of zygosity, and Lewis antibodies are typically IgM with reactivity influenced more by secretor status than by dosage, so they’re not the classic examples of dosage.

More practice questions