RESUMO
Objective To establish a method for detection of RhD(+) red blood cells mixed in D-negative blood by flow cytometry(FCM).Method RhD(+) and RhD(-) RBCs were mixed according to predefined ratios.Cells were indirectly labeled,with IgG anti-D labeled as the first antibody,and FITC-anti-IgG F(ab')2 as the second antibody.The percentage of RhD(+) RBCs was determined by FCM,and the best dosage of IgG anti-D was also defined.The ratio of red cells in the two groups,measured by FCM,was compared with the actual ratio.The consistency of method was also evaluated.Results The effective dosage of IgG anti-D was 1∶4,and 50?l/1?106 cells.When the actual percentages of RhD(+) cell among RhD(-) cells were 2.5%-0.312%,the correlation coefficient between the percentages measured by FCM and the actual percentages was 0.987.The same tubes,containing 10% and 2.5% RhD(+) RBCs,were each tested for 10 times,and their coefficient of variation were 3.4%,and 4.9%,respectively.Conclusion The method of quantifying the RhD(+) RBCs in D-negative blood by FCM is feasible and repeatable,which deserves a further clinical application.