วารสารโลหิตวิทยาและเวชศาสตรบริการโลหิต ปที่ 25 ฉบับที่ 4 ตุลาคม-ธันวาคม 2558 313 Original Article Comparison of IgG ABO Antibody Titers using Conventional Tube Test and Hydrogel Medium Phatchira Thattanon 1 , Chonticha Boonchu 1 , Kamphon Intharanut 2 , Manida Setthakarn 3 , Yong Li 4 and Oytip Nathalang 2 1 Department of Medical Technology; 2 Graduate Program, Faculty of Allied Health Sciences, Thammasat University, Pathumtani; 3 National Blood Centre, Thai Red Cross Society, Bangkok, Thailand; 4 Souzhou Institute of Biomedical Engineering and Technology Chinese Academy of Sciences, Souzhou, China Abstract: Background: ABO antibodies are clinically important in blood transfusion practice. ABO antibody titration has been used to evaluate patient outcomes, especially in ABO-incompatible stem cell and solid organ transplantation and to assess ABO-incompatible transfusion responses. Objective: This study aimed to detect IgG anti-A and anti-B antibodies in group O Thai blood donors by indirect antiglobulin test (IAT) using conventional tube test (CTT) and hydrogel medium (HDM). Materials and Methods: Altogether, 100 serum samples obtained from group O healthy blood donors of the National Blood Centre, Thai Red Cross Society, Bangkok, Thailand were included. IgG anti-A and anti-B titers were tested by IAT using CTT and HDM without washing step. The results of antibody titers and agglutination scores were compared. Results: Among 100 blood donors, there were 51 males and 49 females (M:F = 1:1) and their ages ranged from 18 to 58 years. There were no association between IgG anti-A and anti-B agglutination scores and titers with age and gender. The IgG anti-A, and anti-B titers using IAT-CTT yielded higher agglutination scores than IAT-HDM (p < 0.001). However, a good correlation was obtained in the agglutination titers (anti-A, r = 0.7583 and anti-B, r = 0.7145). To assess the repeatability of IgG ABO antibody detection by IAT using HDM, the mean, standard deviation and coefficient of variation (CV) of 3 serum samples tested in quintuplicate. The CV of agglutination scores is within 5%. Conclusion: From this study, the HDM can be used to perform IAT for determination of IgG ABO antibody titers in order to eliminate washing step. Moreover, it provides reliable results and reproducible testing but the antibody titers tested by IAT-HDM were less than IAT-CTT. Keywords : l ABO antibodies l Hydrogel l Group O l Thai J Hematol Transfus Med 2015;25:313-20. Introduction It is well known that ABO antibodies can cause hemolytic transfusion reactions (HTRs) and hemolytic disease of the fetus and newborn (HDFN). Currently, ABO antibody titration has been used to evaluate patient outcomes, especially in ABO-incompatible stem cell and solid organ transplantation and to assess ABO- incompatible transfusion responses. 1-3 In general, IgM ABO antibodies are mostly caused immune reactions related to HTRs and organ transplant; however, IgG also plays an important role in these reactions. A previous Received 24 June 2015 Accepted 16 October 2015 Requests for reprints should be addressed to Oytip Nathalang, Ph.D., Graduate Program, Faculty of Allied Health Sciences, Thammasat University, Pathumtani 12120. Tel: +662-9869213 Fax: +662-9869057 E-mail: oytipntl@hotmail.com