The Serology of Sd^a Effects of Transfusion and Pregnancy

Abstract

Pre- and posttransfusion antibody titers were performed on 6 patients with anti-Sda transfused with incompatible blood. In 3 of these patients a significant rise in IgG antibody titer was found. The data suggest that in occasional patients the Sda antigen does evoke a secondary immune response. We evaluated 245 pregnant women for the presence of Sda and found that 30% were Sd(a-). This incidence was significantly higher than that found in normal blood donors (4%), but was lower than that described in previous reports. We found that 22% of pregnant women in their first trimester were Sd(a-) whereas at term 36% were Sd(a-). These significantly different incidences of antigen positivity suggest decreased antigen expression with progressing pregnancy, as seen in the Lewis system. No difference was found in the incidence of anti-Sda between pregnant women, either during their first trimester or at term, and normal donors.

Missense mutations in the C-terminal portion of the B4GALNT2-encoded glycosyltransferase underlying the Sd(a−) phenotype

“…In addition, a Sd a -synthesizing β4GalNAc-T in plasma was described already in 1987 [11]. Both Lewis [3] and Sd a [3,12] antigens are progressively lost from human RBCs during pregnancy. Lewis antigens are mainly produced in gastrointestinal cells but adsorbed onto RBCs from plasma [3].…”

Glycoproteomic and Phenotypic Elucidation of B4GALNT2 Expression Variants in the SID Histo-Blood Group System

“…Approximately 91% of the European population carry the antigen on their erythrocytes, although 96–98% express it in tissues such as colon and kidney, or soluble in urine and saliva [ 5 , 6 ]. Among pregnant women, the incidence of Sd(a+) erythrocytes is lower than in normal blood donors [ 3 , 6 , 7 ], which is similar to the Lewis system, where glycolipid antigens are passively adsorbed from plasma by the erythrocytes [ 8 ]. No Sd a is detected on the erythrocytes of newborns, while high levels are detected in their saliva [ 6 ].…”

“…The 2–4% of adults who are truly Sd a negative may produce naturally-occurring antibodies against the antigen. Although rare, hemolytic transfusion reactions have occurred [ 9 , 10 ], and rising IgG titers have been seen in patients after incompatible transfusions [ 7 ]. Especially, transfusion of erythrocytes from donors with particularly high Sd a expression should therefore be avoided in patients with the Sd(a−) phenotype and antibodies to Sd a , since this could lead to hemolytic transfusion reactions.…”