DAntigen

DAntigen is a term that can refer to more than one concept within immunology and related disciplines. In some contexts it is used as an informal label for the D antigen of the Rh blood group system, while in others it denotes a hypothetical or designer antigen used in teaching and research.

The D antigen (RhD) is a surface protein expressed on most human red blood cells. Its presence defines Rh-positive status, while its absence defines Rh-negative status. The D antigen is highly immunogenic, and antibodies against D can cause transfusion reactions and, in pregnancy, hemolytic disease of the newborn. Rh typing and matching are routine in transfusion practice to minimize these risks.

In educational or theoretical writings, DAntigen may be used as a placeholder for a prototypical antigen used to illustrate principles of antigen recognition, epitope mapping, or vaccine design. When used in this way, it is not a standardized or defined biological entity; its properties, such as epitopes or immunogenicity, are described within the context of the example or model being presented.

See also: Antigen, Rh blood group system, Epitope, Immunogenicity.