Abstract: Objective IgG anti-D is the main cause of severe hemolytic disease in newborns. The continuous-flow antibody quantifier has been widely used in Europe, North America and Australia. In China it is usually tested and recorded by titer assay in pregnant women and patients' antiserum. This study mainly compares the correlation between the titer assay and the antibody quantification method, and studies whether the titer assay can represent the amount of antibody. Methods In this study, 17 plasma samples with anti-D titer greater than 64 were compared with the antibody quantification method. The titer method was performed by ORTHOVISION automatic blood type detector for automatic gel column detection. The automatic continuous flow antibody quantizer (WHS-D0120) was used for quantification. Results It was found that the correlation between antibody titer and antibody quantification was r=0.92（P<0.001）. The comparative study between the titer groups of n≥3 (256 groups, 256 groups, 2 048 groups), found that there was a statistically significant difference between the 256 and 512 groups（P<0.001）, and there was no statistical difference between the 256 and 2 048 groups, or between the 512 and 2 048 groups（P>0.05）. In the mononuclear monolayer assay, it was found that there were large phagocytosis differences between the four antibody samples of anti-plasma group with a titer of 256. Conclusion For the anti-D assessment and monitoring of Rh-negative patients and pregnant women's plasma, quantification is more accurate than the titer assay.

Key words: Fetomaternal immunity, Antibodies quantity, Titer, RhD negative