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.

Red blood cell transfusion in patients with anti-Yta.

BACKGROUND: Yta is a high frequency red blood cell (RBC) antigen, present in 99.7% of studied populations. It is extremely immunogenic, and when anti-Yta is present, provision of Yt(a-) blood is often challenging. The objectives of our study were to assess the incidence and severity of acute hemolytic transfusion reactions to Yt(a+) donor RBCs in recipients with preformed anti-Yta and to identify any patient factors associated with severe hemolytic reactions. STUDY DESIGN AND METHODS: Patients with anti-Yta identified by the Red Cell Reference Laboratories of the Australian Red Cross Lifeblood over the past 20 years were included. Their transfusion records were collected via the referring laboratory to ascertain if any patients received RBC transfusion and if there was any evidence of transfusion reactions. RESULTS: Fifty-two patients with anti-Yta were identified; only 12 were confirmed to have received a RBC transfusion. Nine received Yt(a+) or untyped allogeneic RBCs, including four patients who received a total of 16 indirect antiglobulin test (IAT) crossmatch incompatible, likely Yt(a+) RBCs. None of the nine patients had documented acute hemolytic reactions. CONCLUSION: There are limited published data describing the clinical significance of anti-Yta . Based on our data, it appears that transfusing patients with anti-Yta using incompatible crossmatched RBCs does not pose a significant risk of an acute hemolytic transfusion reaction when the antibody reaction strength is weak ≤2+ (0-4) by IAT crossmatch. For strong examples of the antibody, in the absence of other assay data, such as the monocyte monolayer assay, Yt(a-) blood should continue to be sourced where possible.