Immunohematology最新文献

We report a case of a 61-year-old male patient with a complex hematologic history including pre-B acute lymphocytic leukemia, allogeneic stem cell transplant, and newly treated colon cancer followed by diagnosis of high-risk myelodysplastic syndrome (MDS), who exhibited abolishment of D antigen production. The patient's red blood cells (RBCs), which originally typed as group A, D+, again typed as group A, D+, after receiving stem cells from a female donor with the same blood type. The reactivity of the patient's RBCs was strong when tested with anti-D reagent until he was treated for colon cancer. Within 6 months of diagnosis of cancer, he developed a mixed-field D typing result followed by a complete D- phenotype over the course of a few weeks, coinciding with the new diagnosis of MDS and initiation of immunosuppressive therapy. Polymerase chain reaction (PCR) testing revealed no weak or partial D variants, and subsequent Sanger sequencing confirmed the presence of a conventional RHD gene. A more focused analysis by chromosomal microarray identified deletions involving the RHD locus, supporting the hypothesis that active MDS disrupted gene expression. The patient received another stem cell transplant, this time from a group AB, D+ male donor. In a short period of time, MDS re-emerged along with re-identification of microarray mutations encompassing RHD in female cells (from the first donor) even after the second stem cell transplant. However, D expression remained strong, underscoring the presence of enough male donor RHD expression to maintain the D+ phenotype.

When antibody screening results are positive in a patient"s sample, the next step is to identify the specificity of the antibody and plan for transfusion or treatment needs. Most often, the antibody can be identified at the transfusing facility; samples that are not resolved may be referred to an immunohematology reference laboratory. A portion of these referred samples may still not be resolved, and the antibodies in these cases have been termed "antibodies of unidentified or undetermined specificity". In this publication, we selected the term "unknown" for such antibodies. Local medical staff should be involved in the clinical management and transfusion recommendations for these patients. The flow charts described in this article are designed to guide the serologist through steps that may result in a defined antibody specificity, or they may not resolve the specificity, and thus, the antibody remains an "antibody of unknown specificity".

The Rh blood group system was last reviewed in Immunohematology in 2010 (Chou ST, Westhoff CM. The Rh and RhAG blood group systems. Immunohematology 2010;26:178-86). This update focuses on RHD, RhD structure, alterations in D expression, anti-D alloimmunization, and applications of RHD genotyping for weak and discrepant D phenotypes; identification of RHD genotypes that encode partial D phenotypes; and prevention and management of anti-D in pregnancy. Updates to the RHAG system and to RHCE and its encoded antigens are in recent or upcoming publications of Immunohematology, respectively.

Acid elutions are intended to recover IgG antibodies from the red blood cell (RBC) surface. Eluates from samples that are direct antiglobulin test (DAT) positive with complement (C3) only would be expected to be negative. However, elution studies performed on RBCs that are DAT positive with C3 only can produce clinically significant results. Identifying how often clinically relevant information is obtained when elutions are performed on samples DAT positive with C3 alone would aid in developing guidelines for elution performance on these samples and reducing performance of eluates on such samples with clinically insignificant results. Patient samples that are DAT positive with C3 only submitted over an 11.5-month period at the American Red Cross' Immunohematology Reference Laboratory locations were identified. The eluate result, serum result, transfusion history, and patient diagnosis were captured and analyzed. In total, 1171 samples that were DAT positive with C3 only were identified and, of those, 321 (27%) samples had an elution performed. A nonreactive eluate was the most common result. Alloantibodies were identified in 19 (6%) eluates. Panagglutination/autoantibodies was identified in 71 (22%) eluates. Informative eluates were identified as those eluates showing any alloantibody, regardless of serum results, or panagglutination/autoantibody present in the eluate but not concurrently present in the serum (n = 30,9%). Guidelines based on recent transfusion history, indicators of active hemolysis, and autoimmune reactivity concurrently in the serum should be implemented to identify clinically significant information and to reduce the number of uninformative elutions performed.

Unexpected red blood cell (RBC) alloantibodies can lead to hemolytic transfusion reactions and hemolytic disease of the fetus and newborn (HDFN). Screening for these antibodies is essential to ensure transfusion safety and improve patient care. Prevalence and frequency of unexpected antibodies vary among populations, influenced by genetic and demographic factors. This study addresses the gap in data specific to University Hospital, General Sir John Kotelawala Defence University. A retrospective analysis was performed on 20,212 patients (40.74% pregnant women and 59.25% transfusion recipients) from November 2019 to August 2024, assessing the prevalence, distribution, and clinical relevance of RBC alloantibodies. The study found that 0.80 percent of patients were alloimmunized and 28.87 percent of the antibodies were clinically significant. Common antibodies included anti-Le^b (27.27%) and anti-Lea (19.25%); anti-D was the most frequent among Rh antibodies. A significantly higher proportion of pregnant women were alloimmunized compared with transfusion recipients (p < 0.000). Among D- pregnant women, 5.45 percent were alloimmunized, mainly with anti-D. HDFN was identified with either maternal anti-D or anti-E. These findings emphasize the need for early antibody detection and monitoring to enhance transfusion safety, suggesting policy improvements for antibody screening in transfusion and antenatal care in Sri Lanka.

LW^a, LW^ab, LW^b, and LWEM are the four main antigens of the Landsteiner-Weiner (LW) blood group system. LW expression may be weakened during pregnancy and immune dysregulation, with the subsequent appearance of anti-LW. Here, we describe a case of an elderly male patient in whom transfusion of red blood cells (RBCs) became challenging because of the presence of anti-LW. A 61-year-old male patient presented with shortness of breath and a hemoglobin level of 7.0 g/dL, requiring RBC transfusions. Serologic workup of his blood sample showed his RBCs to be group A, D+, but his serum was incompatible with several group A, D+ donor RBC units. Antibody screening showed preferential reactivity with D+ panel RBCs that was abolished when using 0.2 M dithiothreitol-treated RBCs. The patient's serum did not react with known RBCs of Rh_null and LW(a-) phenotypes but reacted strongly with D+ and D- cord RBCs. The patient's sample was genotyped as LW*A/A (c.299A), consistent with the LW(a+b-) phenotype. Subsequent bone marrow examination showed B-lymphoproliferative disorder. The patient required RBC transfusion support because of his underlying disease. Transfusion of group A, D- RBCs was uneventful. The expression of LW in this patient was possibly weakened by his underlying disease, leading to the development of anti-LW. No complications were seen after multiple transfusions of group A, D- RBC units.

This update on the LAN blood group system (Peyrard T. A review of the Lan blood group system. Immunohematology 2013; 29:131-5) reports new ABCB6 alleles encoding Lan- and Lan(+^wk) phenotypes and new functional aspects of the ABCB6 glycoprotein. The L AN blood group system (International Society of Blood Transfusion system 33) consists of one antigen: Lan.

This update on the RHAG blood group system (ISBT 030) (Chou ST, Westhoff CM. The Rh and RhAG blood group systems. Immunohematology 2010;26:178-86) reports the addition of three new low-prevalence antigens carried on the Rh-associated glycoprotein (RhAG). Kg (previously 700045; now RHAG5) has been demonstrated to be antithetical to the previously described high-prevalence DSLK (RHAG3). Two further low-prevalence antigens (RHAG6 and RHAG7) are described, both resulting from rare missense RHAG mutations encoding amino acid changes predicted to be externally located. All three new low-prevalence antigens have been implicated in hemolytic disease of the fetus and newborn. The RHAG system now comprises six antigens, two of high prevalence and four of low prevalence, including one antithetical pair. RHAG4 has been made obsolete.

Variant D antigens can cause variable serologic results when typing with Anti-D reagents. There is limited information regarding the ability of Anti-D reagents to differentiate between D variants defined by RHD genotyping. This study was performed to determine if a panel of 20 U.S. Food and Drug Administration-licensed Anti-D reagents can identify molecularly defined D variants. Red blood cells from 119 donors carrying variant RHD alleles were tested at immediate spin (IS) and/or by the indirect antiglobuin test (IAT) using conventional test tube and/or column agglutination technology. Reaction strength at IS and IAT was reviewed to determine whether a pattern of reactivity could be correlated with a specific D variant. Agglutination results from each sample with each Anti-D reagent were combined to assess overall reactivity. The sample set consisted of 21 D variants, based on prior RHD genotyping. Of these variants, nine categories had three or more samples used for analysis (N = 102); 25 RHD*01W.1, 15 RHD*01W.2, 14 RHD*01W.3, 17 RHD*09.01, 14 RHD*09.03, 4 RHD*01W.4, 23 RHD*07, 4 RHD*10.05, and 6 reference allele RHD*01. As expected, IS showed more negative or weak reactions, and IAT produced more positive reactions with 3+/4+ agglutination strength. RHD*01W.3 samples showed strongest reactivity at IS and IAT. Greatest variation in reactivity was observed with RHD*01W.2, showing weakest overall reactivity at IS. All weak D types had at least one sample that yielded a negative result and one sample with 4+ agglutination at IS. Although there were general patterns of reactivity for each variant tested, no one pattern defined all samples carrying the same RHD allele. This study demonstrated that even with 20 different Anti-D reagents, serologic testing alone is insufficient to define weak or partial D types, characterize the risk for alloanti-D, or determine candidacy for Rh immune globulin. The results illustrate how multiple Anti-D reagents can be used to identify samples that should be reflexed to molecular testing.