The antigrams of commercially prepared red blood cells utilized in the transfusion service include information regarding the following phenotypes:
Cw is an unusual phenotype that is associated with the Rh system that occurs in 2% of whites and is very rare in blacks. Anti-Cw has been seen in individuals who have had no exposure to foreign red cells. The antibody may exhibit dosage (react more strongly with cells from a donor who possesses a double dose of Cw). Given its low prevalence in the population, finding blood negative for the antigen is not difficult.
f(ce) f is an antigen expressed on red cells of individuals who have c and e genes present on the same haplotype. Previously included in a list of so-called "compound antigens," it is likely an entity that arises from conformational changes in the Rhce protein. Anti-f is a very weakly reactive antibody capable of causing HDFN and transfusion reactions. It is often found in the presence of other antibodies. Due to the lack of commercially prepared anti-f, units that are negative for c, e, or both are provided to patients requiring f-negative blood as these donors are, by definition, f-negative.
rhi(Ce) is a compound antigen that is present when C and e are on the same haplotype. Units that are C and e negative are provided to patients who demonstrate anti-rhi.
G antigen is present on most D-positive and all C-positive red blood cells. It results from an amino acid change in the RhD, RhCe, and RhCE proteins. Anti-G reacts as though the serum contains anti-D plus anti-C; namely, all C-positive and all D-positive cells react. Differentiating anti-G from anti-D and anti-C is important during testing for obstetric patients. If anti-G is present and NOT anti-D, the mother is considered a candidate for Rh immune globulin. Adsorption and elution studies are an important part of the workup for these patients. To make the distinction, an immunohematology reference lab may be consulted. For the purpose of routine transfusion, it is not necessary to differentiate anti-G from anti-D plus anti-C. The appropriate course of action is to provide Rh negative, C negative blood.
V (ceS) and VS (eS ) antigens are found in about one-third of a randomly selected African American population. Most V-positive individuals are also VS-positive. Antibodies to these antigens may rarely be encountered.
