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BACKGROUND AND AIMS: 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). MATERIALS AND METHODS: 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). RESULTS: 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. CONCLUSION: 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. [ABSTRACT FROM AUTHOR]

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]