The Serology of Sd^a Effects of Transfusion and Pregnancy

Abstract

Pre- and posttransfusion antibody titers were performed on 6 patients with anti-Sd^a 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 Sd^a 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-Sd^a between pregnant women, either during their first trimester or at term, and normal donors.

Sid Antigen

“…An increased frequency of Sd(a -) red cell phenotype is found among pregnant women [1,15,21] . In different studies, 36% and 75% were Sd(a -) at term, and 25% six weeks post -partum had Sd(a -) red cells [15,21] .…”

“…The incidence of anti -Sd a is increased when Sd(a ++ ) cells are used [21] , and the exceptionally strong Sd(a ++ ) Cad cells are agglutinated by most sera. Sd a antibodies are usually IgM and active at 20 o C [1,2,15] , although IgG anti -Sd a has been identifi ed [21,22] .…”

“…Anti -Sd a are not generally considered a transfusion hazard [1,15,21,23] , though transfusion of Sd(a + ) red cells to patients with anti -Sd a may evoke a signifi cant increase in IgG antibody titre [21] . Most survival studies with 51 Cr -labelled cells in patients with anti -Sd a have shown insignifi cant reduction in red cell survival, even when Sd(a ++ ) cells were used [24,25] .…”

The Sda and Cad glycan antigens and their glycosyltransferase, β1,4GalNAcT‐II, in xenotransplantation

“…Furthermore, human serum anti-Sda antibodies are mainly IgM, 8,9 and anti-Sda IgG antibody titers increase only in patients after the transfusion of Sda-positive erythrocytes. 24 The Tector group's data showed that, after incubation with human serum, knockout of β1,4GalNAcT-II in pig cells decreased the binding of both IgM and IgG. 2,50…”

“…(1) Represents a polylactosamine type 2 chain, which is only one of the several Sda active sugar chains reported to date. (2) Two reported Cad structures (in glycophorin and sialylparagloboside), but are not However, if "super Sda" erythrocytes (Cad erythrocytes) are used to detect antibody in the serum, most sera can agglutinate these cells 24. Two cases of hemolytic transfusion reactions related to Cadexpressing RBCs have been reported 27.…”