Abstract: Objective To study the detection and distribution characteristics of IgG antibody titers and subtypes in newborns with ABO hemolytic disease (ABO-HDN), and provide laboratory diagnostic evidence for clinical diagnosis and treatment of ABO-HDN. Methods 222 newborns were selected as research subjects. Clinical basic data of newborns, hemolysis related testing parameters (TBiL, IBiL, Hb), and data of blue-ray therapy were collected. Three hemolysis tests, IgG antibodies titer and subtype detection were performed using microcolumn gel method. The distribution characteristics of IgG antibody titer and subtype were analyzed, as well as their relationship with the severity of hemolysis in newborns. Results A total of 142 cases were positive and 80 cases were negative. The levels of TBiL and IBiL in the positive group were higher than those in the negative group, and the incidence rate of newborns with type A is higher than that of type B, the difference was statistically significant (P<0.05). In the detection of IgG antibody titers in newborns, the highest titer of free antibody was 16, and the highest titer of release antibody was 32. With the increase of the titer of free or release antibody in newborns, the level of TBiL, IBiL, and Blu-ray treatment duration tended to increase, while Hb levels tended to decrease. IgG1 and IgG1/G3 subtypes were detected in the newborns, and IgG1 and/or IgG3 antibodies were mainly distributed in the high titer group (≥8). Compared with the low titer group (<8), each hemolytic parameter showed statistically significant differences (P<0.05). Conclusion High titer IgG antibodies and IgG1/G3 subtypes are associated with the severity of hemolysis. It can provide important laboratory data support and helpful for clinical diagnosis, prevention and treatment of ABO-HDN.

Key words: ABO hemolytic disease of the newborn, Three hemolysis tests, IgG antibody titer, IgG antibody subtype