A Clinical Case of Weak A Antigen on the Erythrocytes in a Person with Coexistent Anti-A Antibodies

This study investigated a person with an AB۰ discrepancy. Her blood group initially typed at the birth as AB Rh+ (positive); however, it was B Rh+ (positive) or Rh- (negative) when she was in her teens. At room temperature, her erythrocytes were agglutinated by anti-B, and the agglutination was significantly weaker at ۳۷ ºC. As a result, her erythrocytes did not absorb anti-B but anti-A. Furthermore, her erythrocytes were agglutinated by anti-A at ۳۷ ºC with signs of hemolysis in the presence of complement. The unwashed erythrocytes were also agglutinated in an antiglobulin test by polyclonal anti-A at ۳۷ ºC and by heated polyclonal anti-A and anti-A MAB ۲-۸ at room temperature. Moreover, her serum agglutinated A erythrocytes at room temperature with less activity at ۳۷ ºC; however, it agglutinated B erythrocytes at ۳۷ ºC. The ability of the erythrocytes of this person to absorb anti-A came along with the agglutination of her erythrocytes at ۳۷ ºC by polyclonal serum and decreased activity of the serum to agglutinate A erythrocytes at ۳۷ ºC, compared to room temperature. The absence of anti-B absorbance by the person’s erythrocytes was accompanied by the presence of anti-B in the serum, which was active at ۳۷ ºC. The incubation of the person’s serum with ۰ erythrocytes induced the ability of erythrocytes to absorb anti-A and to be hemolyzed by anti-A in the presence of complement in accordance with the person’s characteristics of erythrocytes. The reaction of absorption and agglutination at room temperature and ۳۷ ºC by heated serum with the use of complement may help to reveal both weak A and B antigens and anti-A and anti-B antibodies while AB۰ blood typing.

Keywords:

ABSORPTION , Agglutination , A-transferase , hemolysis , weak A antigen