Detection of weak D antigen by flow cytometry

Flow cytometry was previously applied for analysis of Rh(D) antigen density,therefore it was suggested that the flow cytometry may be used for routine detection of weak D positive phenotypes.This study was purposed to evaluate its practicability.Six weak D positive and 7 DEL individuals were detected by using saline,IAT and absorption/elution test from 2010 to 2011 years.By RHD genotyping,zygosity analysis and sequencing,3 cases of weak D type 15,3 cases of partial D type DVⅠ-Ⅲ and 7 cases of DEL carrying RHD1227A alleles were identified.Taking 2 normal Rh(D)-positive and 2 D-negative samples as controls,all the samples were tested by using flow cytometry,and the median fluorescence intensities were observed as well.The results indicated that all weak D type 15 and partial D type DVI samples were detected to be positive by flow cytometry,as compared with 2 Rh(D)-negative samples(P0.05).Seven 7 DEL samples were tested to be negative(P0.05),although one of 7 DEL was tested as "±" in IAT and strong positive in absorption/elution.The RHD zygosity analysis showed this DEL individual as RHD+/RHD+ homozygote.It is concluded that the sensitivity of detecting D antigen by flow cytometry is similar to that of IAT,but lower than absorption/elution test.As for detecting weak D or partial D antigens,IAT is easier than flow cytometry;as for identifying DEL,the flow cytometry is not sensitive enough.