A new high-prevalence LW antigen detected by an antibody in an Indigenous Australian homozygous for LW*A c.309C>A variant.

BACKGROUND AND OBJECTIVES: The LW gene encodes the LW glycoprotein that carries the antigens of the LW blood group system. LW antigens are distinct from D antigen, however, they are phenotypically related and anti-LW antibodies are often mistaken as anti-D. An antibody was detected in an Australian patient of Aboriginal descent who consistently typed as LW(a+b-). This study aimed to describe the antibody recognizing a high-prevalence antigen on the LW glycoprotein. STUDY DESIGN AND METHODS: Samples from the patient and her four siblings were investigated. DNA was genotyped by single nucleotide polymorphism (SNP)-microarray and massively parallel sequencing (MPS) platforms. Red blood cells (RBCs) were phenotyped using standard haemagglutination techniques. Antibody investigations were performed using a panel of phenotyped RBCs from adults and cord blood cells. RESULTS: SNP-microarray and MPS genotyped all family members as LW*A/A, (c.299A), predicting LW(a+b-). In addition, a novel LW*A c.309C>A single nucleotide variant was detected in all family members. The patient and one of her siblings (M4) were LW c.309C>A homozygous. Antibody from the patient reacted positive to all reagent panel RBCs and cord blood cells but negative with RBCs from LW(a-b-), Rhnull and sibling M4. Antibody failed to react with RBCs treated with dithiothreitol. CONCLUSION: Antibody detected in the patient recognized a novel high-prevalence antigen, LWEM, in the LW blood group system. LWEM-negative patients who developed anti-LWEM can be safely transfused with D+ RBCs, however, D- is preferred. Accurate antibody identification can help better manage allocation of blood products especially when D- RBCs are in short supply.

ABO serology in a case of persistent weak A in a recipient following a group O-matched unrelated bone marrow transplant.

CONCLUSIONS: HLA-matched hematopoietic stem cell transplantation (HSCT) from red blood cell (RBC)-incompatible donors is not uncommon. The engraftment process following ABO-incompatible allogeneic HSCT results in the transition from patient blood group to donor blood group in the recipient. In contrast, most non-hematopoietic tissues retain expression of the patient's original blood group for life, and these antigens may adsorb from the plasma onto the donor-derived RBCs. Correct serologic interpretation of the ABO blood group during this engraftment process can be difficult. We present the serologic findings of a 15-year-old girl of Maori descent, who was diagnosed with acute myeloid leukemia and transplanted with an HLA-matched unrelated group O, D+ bone marrow. Despite engraftment, her RBCs showed persistence of weak A. This case report showcases the importance of awareness and correct serologic interpretation of weak persistence of recipient ABH substance on the patient's RBCs for clinical decision-making, blood component support, and patient wellbeing.

Postpartum anti-D: can we safely reduce the dose?

OBJECTIVE: To assess the potential for dose-reduction of prophylactic anti-D postpartum. DESIGN: Retrospective audit of fetomaternal haemorrhage (FMH) quantitation by flow cytometry. PARTICIPANTS AND SETTING: 5148 consecutive Rhesus D-negative women aged 15-45 years who had FMH estimation by flow cytometry at a central laboratory in Western Australia in the 65 months between 1 August 1999 and 31 January 2005. MAIN OUTCOME MEASURES: Quantitation of FMH volume for adequate prophylactic anti-D administration in a timely fashion. RESULTS: 90.4% (4651/5148) of the women had an FMH volume of 1.0 mL or less of Rh D-positive red cells, and 98.5% (5072/5148) had a volume of less than 2.5 mL. Only 0.4% of cases had an FMH volume of 6.0 mL or greater (range, 6.0-92.4 mL). CONCLUSIONS: This large retrospective audit shows that a currently available dose of 250 IU (50 mg) of anti-D would have been sufficient for 98.5% of the 5148 Rh D-negative women. On the basis of this evidence, a reduction in the recommended routine postpartum dose of anti-D from 625 IU to 250 IU when flow cytometric quantitation for FMH is available should be considered. Adopting such a strategy would ensure the ongoing provision of a valuable human blood product currently in limited supply.