Column Agglutination Technology Research Articles

A rare case of ABO grouping discrepancy due to probable blood group switching which presented as lost antigens detectable only with indigenous reagents in less sensitive platforms compared to highly sensitive automated platforms using non indigenous reagents

Abstract: Blood group switching in the form of loss or diminished expression of RBC antigens has been reported in malignancies and infections. Blood group antigens are present on the red cell surface. ABO blood group system is the most clinically significant system. Some cases can present as grouping discrepancy. Here we present a rare case of ABO grouping discrepancy due to probable blood group switching which presented as lost antigens detectable only with indigenous reagents in less sensitive platforms compared to highly sensitive automated platforms using non indigenous reagents. 66 year old female whose historic blood group was A Rh D positive with history of uneventful transfusion of 2 units of A Rh D positive packed red cell one and half years back now presented with mycoplasma pneumonia and acute pulmonary edema. On routine complete blood count testing her hemoglobin was 3.6 gm%, request send to blood bank for pretransfusion testing. Testing performed via conventional tube technique and ABO blood group discrepancy was noted with forward grouping turned to be A Rh D positive (positive reaction with anti A1 lectin) and on reverse grouping 3+ reactions was observed in both A and B cell giving a picture of O blood group. Blood grouping was performed in different platforms including fully automated, semi automated and manual using commercially available antisera and human plasma as a source of anti A, anti B antibodies for forward grouping. The antisera used in automated platforms are non indigenous and that for manual are indigenous. Discrepancy was noted (Forward A and Reverse O) in CTT with commercially available antisera and human plasma as reagents for forward grouping .The same discrepancy was noted with CAT in neutral card with commercially available antisera for manual grouping. But when grouping performed with Column Agglutination Technology using matrix grouping gel card the discrepancy was resolved reporting the blood group as O. For further confirmation we repeated the blood grouping in another fully automated platform, SPRCA Technology (Immucore NEOIRIS) and in that also no discrepancy noted giving a picture of O group. This patient probably had undergone a blood group switching from A to O by losing some but not all A epitopes and started anti A antibody production. Some A epitopes which were not lost had been picked up by the commercially available antisera intended for manual grouping. These antisera are indigenous in origin. Also when human plasma was used as source of antibodies the A epitopes which were not lost were detected. But when grouping was done with non-indigenous antisera in both manual and automatic platform the A epitopes were not detected. This case points towards the relevance of incorporating indigenous antisera in automated platforms.

A national survey of current immunohematologic testing practices for the diagnosis of autoimmune hemolytic anemia in India.

Autoimmune hemolytic anemia (AIHA) is a common term for several disorders that differ from one another in terms of etiology, pathogenesis, clinical features, and treatment. Management of patients with AIHA has become increasingly evidence-based in recent years. While this development has resulted in therapeutic improvements, it also carries increased requirements for optimal diagnosis using more advanced laboratory tests. Unfortunately, limited data are available from developing countries regarding the testing and transfusion management of patients with AIHA. The main objective of this survey was to explore the current immunohematologic testing practices for the diagnosis of AIHA in India. This online survey consisted of 30 questions, covering the place of work, the number of AIHA cases encountered in the 3 preceding years, testing method(s), transfusion management, and so forth. Individuals representing 89 laboratories completed the survey; only 78 of which responded that AIHA testing was performed in their facility's laboratory. The majority of respondents agreed that the most commonly affected age-group comprised individuals of older than 20 years, with a female preponderance. Regarding transfusion management, respondents indicated that transfusion with "best-match" red blood cell units remains the most common practice. Column-agglutination technology is used by 92 percent of respondents as the primary testing method. Although a monospecific direct antiglobulin test is available at 73 percent of the sites, most of them have limited access to other resources that could diagnose cold or mixed AIHA. Merely 49 percent of responding laboratories have the resources to perform adsorption studies for the detection of alloantibodies. Furthermore, three-cell antibody screening reagents are unavailable at 32 percent of laboratories. In 72 percent of centers, clinical hematologists would prefer to consult a transfusion medicine specialist before administering treatment to AIHA patients. There is unanimous agreement regarding the need for a national registry. The survey data indicate wide variability in testing practices for patients with AIHA in India. Future studies are needed to focus on the feasibility and cost-effectiveness of different testing strategies for developing countries.

Erythrocyte Alloimmunization and Autoimmunization in the Pediatric Population: A Multicenter, Cross-Sectional Study in Central China

Background: Erythrocyte alloantibodies and autoantibodies complicate transfusion. However, the prevalence of erythrocyte alloimmunization and autoimmunization has not been estimated in the Chinese pediatric population. Therefore, we investigated the prevalence of erythrocyte alloimmunization and autoimmunization in the Chinese pediatric population with the aim of developing a reasonable transfusion management policy in children from China. Methods: This study included 30,603 pediatric inpatients who were admitted to three tertiary hospitals in central China from May 2020 to October 2022. Antibody screening was carried out with a three-cell panel by column agglutination technology, and samples with positive screening were analyzed for antibody specificity with a 16-cell identification panel. Clinical details of the patients were collected to identify associations with antibody formation. Results: The alloimmunization rate was 0.55% (169/30,603), and the autoimmunization rate was 0.14% (43/30,603). Alloantibodies comprised 80.09% of the antibodies. The most frequent alloantibodies were anti-M (58.77%), anti-E (9.48%), and anti-P1 (4.27%). Autoantibodies comprised 19.91% of antibodies. Age (p = 0.000), sex (p = 0.016), geographical area (p = 0.000), ABO blood group (p = 0.008), and diagnosis (p = 0.000) were independent risk factors for antibody formation. The risk of antibody formation at the ages of 0–28 days and 1–3 months was zero (odds ratio = 0.000). The antibody distribution was significantly different by age (p = 0.000) and diagnosis (p = 0.000). Conclusion: Repeat pre-transfusion testing for infants less than 4 months of age can be omitted for no risk of antibody formation. MNS system antibodies, especially anti-M, are prominent in younger children, and this decreases with age. Provision of extended phenotype-matched transfusion for Rh system antigens, especially antigen E, is necessary in children to control erythrocyte alloimmunization. The presence of antibodies with high evanescence rates in the pediatric population suggests the pressing need for nationwide shared transfusion records to avoid hemolytic transfusion reactions in children.

Phenotypic Frequency of Clinically Significant Blood Group Antigens (Rh, Kell, Kidd, and Duffy) in Blood Donors of the Blood Center at a Tertiary Care Referral Teaching Hospital in Tirupati, Andhra Pradesh, South India

ABSTRACT Background and Objectives: The knowledge of various blood group antigen and phenotype frequencies in a population is important in selecting compatible blood in alloimmunized patients. Such information in Indian population is very limited. Hence this study was carried out to determine the frequency of clinically significant antigens. Such information in Indian population is very limited. Methods: This study was carried out to determine the frequencies of the D, C, c, E, e, K, k, Fya, Fyb, Jka, and Jkb antigens in 1024 blood donors at our department. Samples were collected for extended antigen typing during March 2016–February 2017 for D, C, c, E, e, K, k, Fya, Fyb, Jka, and Jkb antigens using monoclonal antisera by column agglutination technology. Antigenic and phenotypic frequencies were expressed as percentages. Results: Among the Rh system, “e” antigen was found in 98.6% of donors, followed by D (92%), C (89%), c (56%), and E (17%) with DCe/DCe (R1 R1, 41.4%) as the most common phenotype. “k” was found to be positive in 97% of donors, and K+k− phenotype was found in 0.1% of donors. For Kidd and Duffy blood group system, Jk(a+b+) and Fy(a+b+) were the most common phenotypes with frequency of 56.2% and 47.5%, respectively. MNS antigens were not included on account of financial constraints. Conclusion: Database for antigen frequency of various blood group systems in native donors helps provide antigen-negative compatible blood units to patients with multiple antibodies in order to formulate in-house red cells for antibody detection and identification and for preparing donor registry for rare blood groups.

Prevalence and Clinical Significance of Immunoglobulin G1 and Immunoglobulin G3 Subclasses of Anti-D Antibody in Rh D Alloimmunized Antenatal Women

ABSTRACT Background and Objectives: Hemolytic disease of the fetus and newborn (HDFN) occurs as a result of maternal sensitization to paternal antigens. Studies have shown that the immunoglobulin G (IgG) subclass in maternal serum – particularly the presence of IgG1 and IgG3 either singly or in combination, has an impact on the presence and severity of HDFN. The column agglutination technology is used for the identification of IgG1 and IgG3 subclasses. Therefore, the prevalence of IgG1 and IgG3 subclasses in a cohort of alloimmunized Rh (D) antenatal women at our center was studied and was correlated with severity of HDFN. The aims of this study were as follows: (1) to find out the prevalence of IgG1 and IgG3 subclasses among Rh (D) alloimmunized women and (2) to assess the clinical outcome of newborns born to mothers with respect to IgG subclass. Methodology: This was a descriptive study done on 75 antenatal Rh (D) alloimmunized women who fulfilled the inclusion criteria. Blood samples from study participants were subjected to IgG subtyping using the “DAT IgG1/IgG3 ID card” (Bio-Rad, Switzerland), and the outcome of pregnancy was assessed by categorizing the newborns into mild, moderate, and severe HDFN. The data obtained were analyzed using SPSS version 16. Prevalence was calculated and severity of HDFN was correlated with subclass. Results: Among the study population, 23% of mothers had IgG1 alone. Majority (72%) had both IgG1 + IgG3 subclasses and a few (5%) had IgG2 + IgG4. When the mother had both IgG1 + IgG3 subclasses in their body most newborns had only mild HDFN. Few cases of moderate-to-severe cases of HDFN were seen. Most newborns had only mild HDFN even though there were few moderate-to-severe cases of HDFN. No significant association could be demonstrated between severity of HDFN and type of IgG subclasses. Conclusion: Majority of maternal IgG found in HDFN was a combination of IgG1+IgG3.Such cases exhibited stronger grades of reaction in Indirect Coombs Test. A significant association could not be demonstrated between severity of HDFN and type of IgG subclasses.

P‐IS‐2 | Catching a Cold: Assessment of Cold Antibody Detection on Column Agglutination Technology

P‐IS‐2 | Catching a Cold: Assessment of Cold Antibody Detection on Column Agglutination Technology

Prevalence of blood group antigens among regular blood donors: A single center study from South India with a review of national literature

Background and objectivesThe antigen frequencies vary across different regions and ethnic groups. Hence, we aimed to study the prevalence of blood group antigens in our population and to systemize the zone-wise prevalence of the same across India. Materials and methodsRegular voluntary O group blood donors were screened for 21 blood group antigens; C, c, E, e, K, k, Kpa, Kpb, Jka, Jkb, Fya, Fyb, Lea, Leb, Lua, Lub, P1, M, N, S, s, using commercially available monoclonal antisera by column agglutination technology. A literature search was performed to identify all the studies that reported blood group antigens prevalence to estimate the zone-wise prevalence of these antigens in the country. ResultsA total of 521 participants of 9248 O group donors meeting all the inclusion criteria were included. Among the study group, the male-to-female ratio was 9:1 with a mean age of 32.6 years (±10.01) ranging from 18-60 years. The majority of the donors 446 (85.6%) were D positive. The most common phenotypes among Rh, Lewis, Kell, Duffy, Kidd, Lutheran and MNSs were CcDee (34.93%), Le(a-b+) (61.80%), K-k+(98.27%), Fy(a+b-) 43.19%, Jk(a+b+) 42.61%, Lu(a-b+) ( 99.61%), M+N+ (48.17%), S-s+ (45.29%) respectively. The prevalence of D and E antigens was significantly lower in the South zone compared to other zones of India. ConclusionSignificant difference in the prevalence of blood group antigens is observed between the South and other zones of India. Zone-wise prevalence of blood group phenotypes is essential in the timely management of alloimmunized patients.

A rapid ABO and RhD test demonstrates high fidelity to blood bank testing for RhD typing.

The rapid provision of blood products is life-saving for patients with massive hemorrhage. Ideally, RhD-negative blood products would be supplied to a woman of childbearing potential whose Rh type is unknown due to the risk of D-alloimmunization and the potential for hemolytic disease of the fetus and newborn to occur if RhD-positive blood products are transfused. Therefore, there is a need for a test that rapidly determines her RhD type. This study compared the RhD type determined using a rapid ABO and RhD test to the RhD type determined by an immunohematology reference laboratory. After receiving ethics review board approval, 200 random, unique, deidentified patient samples that had undergone routine pretransfusion testing in an immunohematology reference laboratory using column agglutination technology were collected and tested using a rapid ABO and RhD test (Eldoncard Home kit 2511). The RhD typing results from these two methods were compared to determine the accuracy of the rapid ABO and RhD test. The rapid ABO and RhD test produced results that were concordant with the transfusion service's results in 199/200 (99.5%) of cases, with a negative predictive value of 98.2% and 99.3% sensitivity. The single outlier was likely an RhD variant due to its serological characteristics. These data indicate that this rapid ABO and RhD test could be used for the rapid determination of a patient's RhD type, perhaps even in the emergency department, which could guide the selection of blood products provided during their resuscitation.

A COMPARISION OF CONVENTIONAL TUBE METHOD AND COLUMN AGGLUTINATION TECHNOLOGY IN AN IMMUNOHEMATOLOGY LABORATORY

Background: Rapid technological advancements in pretransfusion procedures in an immuno-hematological laboratory are a result of the increased focus on the quality and safety of blood products. Numerous automated pretransfusion testing platforms have been developed as a result of the inherent drawbacks of the gold standard conventional tube method. The invention of Column Agglutination Technology was the biggest advancement among these. Aim: 1. To compare the results of blood grouping and crossmatching by Conventional Tube Method and Column Agglutination Technology. 2. To statistically evaluate the results obtained between Column Agglutination Technology and Conventional Tube Technique in our immunohematology laboratory. Materials and Methods: The study was performed in blood bank of a tertiary hospital in Mangalore during the month of January,2022 in which 500 samples were subjected to blood grouping and cross matching. The data obtained was extensively studied. Sensitivity, specicity and statistical analysis were done by Fisher's exact test. Results: In comparative evaluation of CAT and CTT of 500 samples, there was concordance rate of 99.6% in blood grouping and concordance of 99.8% in crossmatching. In both the scenarios, the discordance was evaluated and found CATis superior to CTT. The most common blood group of both studies was 0 positive. Statistical analysis using Fisher's test proved statistically signicant difference between grouping and cross-matching via both tests with a p value of 0.000001 and 0.01 respectively. The sensitivity and specicity of both tests showed CAT to be superior with 100% sensitivity and 100% specicity while in CTT, the sensitivity was 100% with 66.6% specicity. Conclusion: The study establishes that CAT is more sensitive, specic, rapid, reliable procedure and is a better substitute of CTT in pretransfusion testing.

A prospective observational study to evaluate effect of heat inactivation on ABO titers performed by column agglutination technology and conventional tube technique.

When determining ABO antibody titers, immunoglobulin G (IgG) antibodies can be masked by immunoglobulin M (IgM) antibodies. Hence, the measurement of actual concentration of IgG requires methods like heat inactivation (HI) of plasma. This study was aimed at determining the effects of HI on IgM and IgG titers performed by conventional tube technique (CTT) and column agglutination technique (CAT). This was a prospective, observational study conducted from October 2019 to March 2020. All consecutive A, B, and O group donors who gave consent for participation were included. All samples were consecutively tested by CTT and CAT, before and after HI (pCTT, pCAT). A total of 300 donors were included. IgG titers were found to be more than IgM titers. For group O, IgG titer results were higher for both anti-A and anti-B compared to group A and B. For group A, B, and O, pretreatment results were higher than posttreatment IgG titer results. Median anti-A titers were similar to median anti-B titers across all categories. Median IgM and IgG titers were higher for group O individuals than nongroup O individuals. There was reduction in IgG and IgM titers after HI of plasma. One log reduction in median titers was observed when ABO titers were performed by CAT and CTT. There is one log difference between median antibody titers estimated using heat inactivated and nonheat inactivated plasma. The use of HI for ABO isoagglutinin titer estimation can be considered in low resource settings.

Type and Screen Method versus Antihuman Globulin Crossmatch in Pretransfusion Testing: A Cross-sectional Study

Introduction: Blood transfusion remains the primary modality of treatment for many serious and common diseases. According to the International Society of Blood Transfusion (ISBT), there are about 349 blood group antigens, out of which only about 25-28 antigens are known to cause acute or delayed type of haemolytic transfusion reactions which could be prevented by Pretransfusion Testing (PTT). Regulated pretransfusion tests include ABO blood grouping, Rh typing, antibody detection, antibody identification and compatibility testing. The purpose of compatibility tests is to demonstrate invitro red cell antigen-antibody reaction. The Antihuman Globulin (AHG) crossmatch testing can assure ABO compatibility between donor and patient blood as well as detect most clinically significant antibodies. Type and Screen (T&S) is a procedure carried out as part of PTT in which the recipient’s blood sample is tested for ABO group, RhD T&S for unexpected antibodies. Aim: To compare T&S method of PTT with AHG crossmatch. Materials and Methods: This cross-sectional study was conducted in the department of Transfusion medicine at Government Royapettah Hospital, Chennai and The Tamil Nadu Dr. MGR Medical University, Chennai, Tamil Nadu, India from June 2012 to December 2013. T&S was performed on 1,040 recipients’ (510 males and 530 females) samples. All these samples were subjected to AHG crossmatch with ABO group and RhD type matched donor samples to assess the compatibility between donor and recipient by using column agglutination technology. Statistical analysis was carried out using Statistical Package for the Social Sciences (SPSS) version 11.0. Results: The prevalence of unexpected antibodies in the recipient population was 1.06%. Among the 1,040 recipients’ blood samples, 11 samples were found to have unexpected antibodies. Out of these 11 samples, 10 showed exact antibodies and the remaining one sample with negative antibody screening was found to be incompatible with AHG crossmatch. The sensitivity and specificity of T&S method in comparison to AHG crossmatch was 87.50% and 99.71%, respectively. Conclusion: The sensitivity and specificity of T&S is as acceptable as AHG crossmatch. However, in view of one sample with false negative antibody screening in the study population, it is imperative to know the phenotyping of Red Blood Cells (RBC) antigens of the native population before getting away with AHG crossmatch.

A Prospective, Observational Study to Assess Effect of DTT Treatment on ABO Isoagglutinin Titers in O Blood Group Donors

To determine actual concentration of clinically significant IgG antibodies, there is need to inactivate IgM antibodies. Aim of this study was to study effect of dithiothreitol (DTT) on ABO isoagglutinin titers performed by column agglutination technology (CAT) and conventional tube technique (CTT) and to compare results obtained by DTT treatment.

A multicenter prospective observational study on the use of type and screen method versus conventional type and crossmatch policy for pre-transfusion testing in the Indian population.

Despite knowing the benefits of the type and screen (TS) method in pre-transfusion testing (PTT), most transfusion centers in developing countries continue to be reluctant to adopt a TS strategy over the conventional type and antihuman globulin (AHG) crossmatch (TX) policy in their routine laboratory practice because of the cost of obtaining antibody screening reagents. To generate strong evidence, this multicenter, observational study was conducted in which we collected data prospectively over a 1-year period from six major blood centers in India. The primary objective of this study was to identify the discordance between TS and TX results. A secondary objective was to identify the allo-antibody specificity in patients with positive antibody detection tests. All patients with orders for red blood cell transfusion who met patient selection criteria were subjected to parallel testing by column agglutination technology (CAT) for both the antibody detection test (screen) using a commercial three-cell panel and for the AHG crossmatch. A total of 21,842 patients were tested. In 148 patients with incompatible crossmatches, samples from six patients gave negative results with the antibody detection test, whereas the antibody detection test was positive in samples from 118 patients among the 21,694 crossmatch-compatible cases. The TS approach achieved a positive percent agreement of 95.95 and was found to be significantly effective in preventing the transfusion of serologically incompatible blood. The risk associated with abbreviating the AHG crossmatch was found to be 0.009 percent. Most of the identified clinically significant alloantibodies were directed to Rh antigens (D>E>c>C>e), followed by anti-K and anti-M. This study has generated sufficient robust data for the Indian population by including patients from all major geographical areas of the country and concluded a satisfactory agreement level as well as non-inferiority to the current PTT policy. Therefore, TS policy can be implemented in developing countries with no compromise on blood safety, provided sufficient technical and infrastructural support are available.

Occurrence of Erythrocyte Alloimmunization in Women Attending Antenatal Care Clinic

Background and Objectives: There is limited literature available on the alloimmunization rates among pregnant women in India. Our primary aim was to estimate the occurrence of irregular erythrocyte alloantibody (IEA) immunization amongst women attending our antenatal care (ANC) clinic and to guide our obstetricians for improved ANC as well as their fetal outcomes. Methods: A cross-sectional study was performed at the blood center in North India over 12 months. We recruited a total of 212 study participants. Antibody screening and identification were performed by using semi-automated column agglutination technology and commercially available 3-red cell antibody screen panel with reagent cards having anti-human globulin (AHG) (Ortho Clinical Diagnostics Inc., USA) and 11-red cell antibody identification panel with reagent cards having AHG (Resolve Panel A; Ortho Clinical Diagnostics Inc., USA) respectively. Once identified, the semi-quantitative doubling dilutions, i.e., serial titrations of the respective IEA were performed by the conventional tube technique to assess their potency. The association of various antibodies identified was analyzed using the Pearson's Chi-square test. Results: Of the 7248 pregnant women attending our ANC clinics, the antibody screening was requested for 212 cases. Out of these, 10.8% (n = 23/212) of women were positive and were sensitized both by active and passive immunization. Their average age (in years) was 27.6 ± 3.52 (20 to 34). The majority belonged to the Dehradun district of Uttarakhand. ABO system-wise, the most common type amongst the included subjects was A as recorded in 34.4%, followed by B (30.18%), O (24.12%) and AB (11.3%), respectively. Rh system-wise, nearly 47% (n=100/212) of subjects had Rh (D) negative blood group. Interestingly, amongst these 23 ANC cases with positive IAT, nearly 13% had a history of having received a blood transfusion. Conclusion: To sum up, the screening of majority of ANC in our hospital is restricted to Rh (D) negative pregnancies. Perhaps, more awareness among obstetricians regarding the universal screening of all ANC cases irrespective of their Rh (D) status is the need of the hour.

An independent reader system that parallels critical steps of full automation capability for immunohematology testing

IntroductionUse of fully automated solutions to perform analysis of immunohematology tests is highly desirable as it delivers an improved level of safety and security of results. However, full automation may not be feasible financially and practically in all circumstances. A solution that addresses most of the process step hazards of manual testing can assist in achieving a higher level of confidence in and safety of test results. MethodsThe study utilized a column agglutination technology (ORTHO BioVue ® System) to test a variety of samples on the ORTHO VISION ® Analyzer and compare to the reader capability of the ORTHO OPTIX™ Reader. Both direct agglutination and direct/indirect antiglobulin test methods were evaluated. The data was analysed for per cent agreement and for concordance at the lower bound 95% confidence interval. The acceptance criteria for concordance for direct agglutination was ≥ 99.4% and for indirect agglutination was ≥ 98.0% at a lower bound 95% confidence interval. ResultsThere were 13,805 columns producing 5174 interpreted tests for direct agglutination and 5998 columns producing 2958 interpreted direct/indirect antiglobulin tests evaluated. Testing demonstrated that direct agglutination and direct/indirect antiglobulin testing generated greater than 99% concordance between the fully automated instrument system and the reader. ConclusionsThe reader exceeded the approval criteria set for the study which demonstrates the capability to address the desire for a solution that moves manual testing to an enhanced level which achieves improved safety and security in immunohematology testing.

Comparison of Anti-D Titration Testing by Automated Column Agglutination Technology on Glass-Beads and Standard Tube Method

Comparison of Anti-D Titration Testing by Automated Column Agglutination Technology on Glass-Beads and Standard Tube Method

Comparative assessment of dithiothreitol‐treated ABO isoagglutinin titres performed by two methods

Background and aimsTo determine actual concentration of clinically significant IgG antibodies, there is need to inactivate IgM antibodies. Aim of this study was to study effect of dithiothreitol (DTT) on ABO isoagglutinin titres performed by column agglutination technology (CAT) and conventional tube technique (CTT) and to compare results obtained by DTT treatment.Materials and methodsThis was a prospective, observational study conducted from October 2019 to March 2020. All consecutive A, B and O group donors were included. All samples were consecutively tested by CTT and CAT, before and after DTT treatment (pCTT, pCAT).ResultsA total of 300 donors were included, 100 each from group A, B and O. IgG titres were found to be more than IgM titres. For group O, IgG titre results were higher for both anti‐A and anti‐B compared with group A and B. Reduction in IgG titres was observed with DTT. With the use of DTT, one log reduction in group O IgG titres was observed and three log reduction in group A/B IgG titres was observed. When comparing anti‐A and anti‐B IgG results for group O individuals, results of CTT and pCAT were not found to be significant. IgG measurement of anti‐A and anti‐B of group O individuals showed strong to very strong correlation between CTT and CAT, before and after DTT treatment.ConclusionThere is significant difference between antibody titres estimated using DTT‐treated and DTT‐untreated plasma. Use of DTT for ABO isoagglutinin titre estimation is recommended.

Comparison between tube test and automated column agglutination technology on VISION Max for anti-A/B isoagglutinin titres: A multidimensional analysis.

VISION Max (Ortho Clinical Diagnostics, Raritan, NJ) measures anti-A/B isoagglutinin titres using automated column agglutination technology (CAT). We compared tube test (TT) and CAT of VISION Max comprehensively, including failure mode and effect analysis (FMEA), turnaround time (TAT) and cost, and suggested modified CAT (MCAT). For 100 samples (each 25 for blood type A, B and O with anti-A and anti-B), anti-A/B isoagglutinin titres were measured by TT and CAT (1:2-1:1024 dilution), as well as by MCAT (with agglutination at 1:32 dilution, then perform additional testing from 1:64 to 1:1024). We assessed the agreement and correlation between TT and CAT and compared FMEA (risk priority number [RPN] score), TAT (h:min:sec) and cost (US dollar, US $) among TT, CAT and MCAT. TT and CAT showed overall substantial agreement (k=0.73) and high correlation (ρ ≥ 0.75) except blood type O with anti-A (ρ=0.68). Compared with TT, CAT showed lower RPN scores in FMEA and similar TAT and cost (FMEA, 33,700 vs. 184,300; TAT, 15:23:00 vs. 14:26:40; cost, 1377.4 vs. 1312.4, respectively). Regarding FMEA, TAT and cost, MCAT was superior to CAT or TT (43,810; 13:28:00; 899.2, respectively). This is the first multidimensional analysis on VISION Max CAT for measuring anti-A/B isoagglutinin titres. The results of anti-A/B isoagglutinin titres by CAT were comparable with those of TT. MCAT would be a safe, time-saving and cost-effective alternative to TT and CAT in high-volume blood bank laboratories.

A prospective, observational study to compare effect of DTT treatment and heat inactivation on ABO isoagglutinin titers in O blood group donors

Background and aimsIn order to determine actual concentration of clinically significant IgG antibodies, there is a need to inactivate IgM antibodies, which can be performed by DTT or heat. The aim of the present study was to compare the effect of DTT treatment and heat inactivation (HI) on ABO isoagglutinin titres performed by column agglutination technology (CAT) and conventional tube technique (CTT).Materials and methodsThis was a prospective, observational study conducted from October 2018 to March 2020. All consecutive O group donors were included. Serum from each donor was treated with DTT, and heat and tests were performed by CTT and CAT before and after treatment.ResultsA total of 2005 donors were included. 401 (20%) samples had inter‐observer variation by CTT, and 69 (3·4%) had inter‐observer variation by CAT. Median anti‐A and anti‐B titre results were higher with CAT as compared to CTT. Median anti‐A and anti‐B IgG titre results showed a one‐ to twofold difference between CTT and CAT with higher titres reported by CAT. Median IgM titres decreased two‐ to threefold after DTT treatment, whereas onefold decrease was confirmed after HI. Concordance was found to be poor. However, correlation was found to be strong.ConclusionThere is overestimation of ABO IgG antibody titres and hence, estimation of ABO IgG titres after inactivation of IgM antibodies is strongly recommended. DTT treatment was found to be superior to HI in terms of efficiency in elimination of IgM activity.

Comparative evaluation of the conventional tube test and column agglutination technology for ABO antibody titration in healthy individuals: a report from India.

Abstract Determination of accurate anti-A/-B titers is important for treatment selection in ABO-incompatible stem cell and solid-organ transplants. The standard method for ABO antibody titration is the conventional tube test (CTT). Dithiothreitol (DTT) is commonly used to inactivate the IgM antibody component. The aim of this study was to compare six different methods for ABO antibody titration and to observe the effectiveness of DTT on antibody estimation. A total of 90 healthy voluntary blood donors were enrolled in this study, including 30 each for blood groups A, B, and O. Antibody titrations were performed and tested using the CTT-immediate spin (IS), CTT-antihuman globulin (AHG) with and without DTT, column agglutination technology (CAT)-IS, and CAT-AHG with and without DTT methods. Bead-CAT was used, and the positive cutoff value was set to 1+ for each method to determine the endpoint of the titer. The median values of anti-A/-B titers by IS were found to be higher than those values by AHG in CTT and CAT among group B and A individuals, whereas no statistically significant differences were observed in values from group O individuals for IS and AHG anti-A/-B titers, estimated by each method. Although there was positive correlation between the anti-A/-B titer results obtained using the CTT and CAT in all blood groups, testing using AHG showed poor agreement with and without DTT pretreatment (kappa value of 0.11 and 0.20, respectively). Moderate agreement was observed between CTT-IS and CAT-IS (kappa value of 0.46). Median anti-A/-B AHG titers were reduced by the use of DTT in all blood group samples. Significant differences in the interpretability of anti-A/-B titers were observed among different methods. A uniform approach for selecting the method for ABO antibody titration is highly recommended, and DTT pretreatment of plasma to neutralize IgM activity should be considered to obtain precise values of IgG anti-A/-B titers. Immunohematology 2021;37:25–32 .