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Background and aims: In 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 methods: This 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. Results: A 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. Conclusion: There 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. [ABSTRACT FROM AUTHOR]

Background and aims Antibody titration by the manual method has certain limitations. The aim of this study was to compare the manual conventional test tube technique (CTT) with semi-automated, column agglutination technique (CAT) and fully automated haemagglutination/solid-phase red cell adherence (HA/SPRCA) technology in measuring antibody titres of anti-A and anti-B isoagglutinins of blood group O blood donors. The median IgM and IgG antibody titres with 1+, 2+ and 3+ end-points were determined for each technology, and the agreement and correlation between results of the 3 technologies were evaluated. Materials and methods This was a prospective, observational study conducted from October 2018 to March 2020. All consecutive O group blood donors, who donated blood at the Department of Transfusion Medicine at a tertiary healthcare centre, were included in the study. All samples were consecutively tested by CTT, CAT and HA/SPRCA, and the results were recorded and compared. Results A total of 2005 donors were included. Inter-observer variation was observed in 295 (14.71%) samples by the CTT and in 51 (2.54%) by the CAT. There was 43.4% and 40.3% agreement of anti-A IgM and IgG titres between CAT (2+ strength) and CTT (1+ strength), respectively. The agreement for anti-B IgM and IgG titres between CAT (2+ strength) and CTT (1+ strength) was 43.6% and 32%, respectively. While a strong correlation was found between CTT (1+ strength) and CAT (1+, 2+ strengths) for both IgM and IgG measurements of anti-A and anti-B isoagglutinins, the correlation between CTT (1+ strength) and HA/SPRCA (1+, 2+ strengths) was found to be weak. The median IgM titres for anti-A and anti-B were lower than the median IgG titres. Conclusion The antibody titration levels were higher with CAT than with CTT, and those of HA/SPRCA were lower than those of CTT. Transfusion services need to decide which method would provide higher benefit to their patient population. [ABSTRACT FROM AUTHOR]