Hemolytic disease of the newborn due to anti-U

Abstract

Anti-U is a rare red blood cell alloantibody that has been found exclusively in blacks. It can cause hemolytic disease of the newborn and hemolytic transfusion reactions. We describe the case of a female newborn presenting a strongly positive direct antiglobulin test due to an IgG antibody in cord blood. Anti-U was recovered from cord blood using acid eluate technique. Her mother presented positive screening of antibodies with anti-U identified at delivery. It was of IgG1 and IgG3 subclasses and showed a titer of 32. Monocyte monolayer assay showed moderate interaction of Fc receptors with maternal serum with a positive result (3.1%). The newborn was treated only with 48 hours of phototherapy for mild hemolytic disease. She recovered well and was discharged on the 4th day of life. We conclude that whenever an antibody against a high frequency erythrocyte antigen is identified in brown and black pregnant women, anti-U must be investigated.

Acute Hemolysis in a Patient with Anti-U Despite a Negative MMA Test

“…Additionally, anti-U has been identified as an auto-specificity in individuals with warm autoimmune hemolytic anemia. [3][4][5][6][7][8] To further complicate the issue, this patient was Rh-negative. Since only 8% of African Americans are Rh-negative, the chances of finding a compatible Rh-negative, U-African American donor is <0.1%.…”

Hemolytic disease of the fetus and newborn caused by anti-D and anti-S alloantibodies: a case report

“…The serological tests for the diagnosis of HDFN includes a positive direct Coombs' test (DCT) on the baby's red blood cells and the presence of an IgG red cell alloantibody in both cord blood eluate and maternal sera. The presence of the corresponding antigen on cord cells confirms the diagnosis of HDFN [4,5]. The most severe HDFN is caused by IgG antibodies directed against D, c or K antigens on the fetal red cells, but any IgG antibodies can cause HDFN [6].…”

Anti-U antibody in pregnancy: a rare antibody causing hemolytic disease

“…Fewer than 1% of Africans are U‐negative and can produce allo‐anti‐U antibody (2). Only 14 women in 21 pregnancies have been reported as being positive for anti‐U antibodies (3–5). From the limited literature available, no direct correlation between antibody titer levels and clinical phenotype has been determined, varying from 1:4 to 1:16 000 (3–5).…”

“…Only 14 women in 21 pregnancies have been reported as being positive for anti‐U antibodies (3–5). From the limited literature available, no direct correlation between antibody titer levels and clinical phenotype has been determined, varying from 1:4 to 1:16 000 (3–5). It does appear that there is a threshold level of 1:32, below which significant hemolytic disease does not occur, while no clinically significant hemolysis has been noticed even at titers as high as 1:4 000 (3).…”

“…It does appear that there is a threshold level of 1:32, below which significant hemolytic disease does not occur, while no clinically significant hemolysis has been noticed even at titers as high as 1:4 000 (3). The lowest reported anti‐U titers associated with severe hemolytic disease requiring exchange transfusion is 1:512, but intrauterine death can occur at titers of less than 1:640 (3–5).…”