Immunohematology最新文献

The importance of identifying variant alleles among blood donors is significant to the safety of transfusion for recipients. Molecular methods have become more prominent in the routine process of antigen typing donor units. Some variant antigens cannot be detected using only serologic methods. Molecular testing allows the determination of nucleotide sequences that are used to predict a phenotype. Antigens of the Kell blood group system are known for being highly immunogenic and causing adverse reactions upon antibody formation. A female white blood donor who typed Kp(b-) using serologic methods on multiple donations since 2005 was the subject of a typing discrepancy investigation. Routine genotyping using a commercial genotyping kit (HemoID DQS Panel; Agena Bioscience, San Diego, CA) predicted the donor to type Kp(a+b+). Investigation of the discrepancy between these two results identified a rare single nucleotide variant in the KEL gene at nucleotide position c.948G>T that alters amino acid residue 316 from tryptophan (Trp) to cysteine (Cys). After discovery of the novel allele, adsorption and elution studies were performed to see if there was weakened Kp^b expression. The elution studies yielded negative results, which indicated that Kp^b is not expressed. The KEL transcripts expressed by the donor were determined using cDNA analysis, and the predicted amino acid sequence of the novel allele was modeled to investigate the impact of the amino acid sequence on the structure of the KEL polypeptide. Both SWISS-MODEL and Robetta software were used to evaluate the impact of the p.Trp316Cys on the three-dimensional protein structure. There was no conformational change noted with SWISS-MODEL, whereas the Robetta software showed a significant conformational change compared with the normal Kp(b+) reference sequence. Because the donor is homozygous for variants associated with k and Js^b expression, it was not possible to determine whether the novel allele is associated with loss of Kp^b only or loss of all Kell antigens.

As population diversity in the United States expands, understanding antigen prevalence by ethnic group is essential. Differences in antigen prevalence among ethnicities have caused increased alloimmunization in chronically transfused patients. Recognizing these differences in patients and donors can reduce the risk of patients developing alloantibodies. Also, determining the antigen prevalence by ethnicity will improve the ability of blood centers to have compatible blood available. Thus far, there has not been significant published data on antigen prevalence of the U.S. Hispanic population. A retrospective cross-sectional study was performed to determine the prevalence of red blood cell (RBC) antigens, as determined by human erythrocyte antigen genotyping, in South Texas Hispanic blood donors. A total of 3455 donors, seen from 1 January 2015 to 31 May 2020, were included in the study. These donors met the inclusion criteria of self-selecting Hispanic ethnicity and successfully donating a RBC component. The antigen results for each included donor were entered into a data collection spreadsheet. The prevalence of each antigen was calculated. A binomial test was performed to determine if the observed results are statistically different as compared with the published prevalence of antigens in white and black populations. After statistical analysis, the p value for most antigens was statistically significant (p < 0.05). The Kidd blood group antigens were the only major antigens that did not show a significant difference. Cohen's h showed a large effect size for most antigens when compared with those of the black population and a small to medium effect size when compared with those of the white population. For most blood groups antigens, their prevalence in Hispanic donors was significantly different than that published for both white and black populations.

The use of probiotics brings numerous benefits to the immune system, including an increase in antibody production. The development of ABO antibodies may occur naturally due to the bacteria of the intestinal microbiota. However, high titers of ABO antibodies can lead to hemolytic disease of the fetus and newborn and can cause immune transfusion reactions. In this context, this study aimed to evaluate the effect of probiotic consumption on ABO antibody titers in humans. ABO blood group, ABO antibody titer, and fecal pH and Bifidobacteria concentration were determined for 126 healthy individuals before and after daily consumption of yogurt containing Lactobacillus acidophilus and Bifidobacterium lactis over a 1-month period. No changes in fecal pH were observed after probiotic consumption, regardless of ABO blood group. There was, however, an increase in the fecal concentration of Bifidobacteria in individuals with blood group A but not for those with group B or O. A decrease in the titer of anti-B was observed, despite the increase in the concentration of Bifidobacteria in feces being unrelated to fecal pH, in blood group A individuals. Our study, therefore, sought to understand the relationship between probiotics and the antibody titer of the ABO blood system. Despite our findings, further human studies are needed with other probiotic strains and molecular analyses of the intestinal microbiota.

P is a high-prevalence antigen present in 99.9 percent of the population and is fully developed at birth. P- individuals form naturally occurring antibodies against P, which are often of immunoglobulin (Ig)M and/or IgG type, very potent in complement activation, and able to cause serious intravascular hemolytic transfusion reactions. Some people with anti-P have the rare P₁ ^k phenotype, which lacks P in the presence of P1 and P^k. Blood transfusion in patients with anti-P is challenging, as is described here. A male patient without a history of blood transfusion was admitted for a planned cardiac surgery. The preoperative ABO blood group could not be determined because of unexpected reactions in the reverse grouping, and all red blood cells (RBCs) in the antibody detection test were positive, except for the autocontrol. Further analysis of the patient's sample confirmed the presence of the P₁ ^k phenotype, and anti-P was identified. If transfusion was needed, P- blood would be required, and the only P- RBCs available were at the national Sanquin Bank of Frozen Blood. These units are limited, expensive, and only available for 48 hours after thawing. In the case of massive blood loss, first ABO and Rh-compatible units should be transfused, followed by P- units after the bleeding stops. In our case, the surgery was conducted without transfusion. This case illustrates the importance of preoperative ABO blood group testing and antibody screening in cases where blood loss can be expected. In recent years, more focus has been put on patient blood management. A good collaboration between the local laboratory, surgery department, and dedicated blood transfusion laboratory is critical to prevent unnecessary incompatible blood transfusions with potentially serious outcomes.

The relationship between ABO blood group and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 - coronavirus disease 19 [COVID-19]) infection has been investigated, and several studies have reported discordant findings. This systematic review and meta-analysis study were conducted to investigate the relationship between ABO blood group and COVID-19 infection. The international databases Institute for Scientific Information (ISI)/Web of Science, PubMed, and Scopus were systematically searched from 1 January 2020 through 14 June 2021. Twenty-seven studies met the inclusion criteria for meta-analysis including 23,285 COVID-19 case subjects and 590,593 control subjects. The odds of having each blood group among COVID-19 patients compared with control subjects were calculated. The random effects model was used to obtain the overall pooled odds ratio (OR). Publication bias and subgroup and sensitivity analyses were performed to explore the source of heterogeneity. According to the random effects model, the results indicated that the pooled estimates of OR (95% confidence interval) for blood groups A, O, B, and AB were 1.26 (1.13-1.40), 0.77 (0.71-0.82), 1.05 (0.99-1.12), and 1.11 (0.99-1.25), respectively. Therefore, individuals infected with COVID-19 have higher odds of having blood group A and lower odds of having blood group O. In conclusion, this study indicated that individuals with blood group A are more susceptible to COVID-19 infection, whereas those with blood group O are less susceptible to COVID-19 infection. However, further studies are warranted to support these findings.

A woman with autoimmune hemolytic anemia (AIHA) presented in the emergency department with life-threatening anemia (hemoglobin 3 g/dL). Exaggeration of preexisting chronic anemia to severe anemia after a recent red blood cell (RBC) transfusion led to suspicion of delayed hemolytic transfusion reaction. Given the urgency for transfusion along with a stronger suspicion for coexistence of an alloantibody, the dilution method proposed by Lawrence Petz and George Garratty was used to find an RBC unit for transfusion. An alloantibody with Fy^b specificity was identified, which was masked by the coexistent autoantibody. This method is based on the assumption that the titers of an alloantibody are higher than that of autoantibody. Diluting the autoantibody would reveal the alloantibody and, for this purpose, a serial doubling dilution of serum is performed. This method has an important limitation of missing any alloantibodies with titers less than that of the autoantibody. In spite of this, this method may be of use at a resource-poor setting, where trained personnel and other reagents intended for advanced immunohematology methods are unavailable.

Thiol reagents dithiothreitol (DTT) and 2-mercaptoethanol (2-ME) are sulfhydryl reagents that can be used to disperse cold autoagglutinins coating red blood cells (RBCs). DTT and 2-ME are primarily used when warm washing of the coated RBCs fails to successfully disperse the cold autoantibody. Using a weak concentration of DTT or 2-ME, the cold IgM agglutinin can be removed from the coated RBCs without disrupting the IgG or complement coating the RBCs. The treated RBCs can be used for ABO typing, antigen typing, or the direct antiglobulin test.