Detection and quantitation of ABO RBC chimerism by a modified coil planet centrifuge method.

Abstract

Differential agglutination procedures and flow cytometric analysis have been used for detecting and quantitating mixed cell populations. For more than 20 years in our laboratory, a differential agglutination method using the coil planet centrifuge and polyclonal anti-A or anti-B has been used. However, it is now difficult to obtain polyclonal antisera, and it is unknown whether MoAbs can take the place of polyclonal antisera in the coil planet centrifuge method. Polyclonal antisera and MoAbs were filled into a coil first and then unsensitized packed RBCs from ABO variants, and from chimeras and patients after ABO-incompatible HPC trans- plantation (HPCT) were loaded. After centrifugation, agglutinated and nonagglutinated RBCs were collected, hemolyzed, and subjected to colorimetric analysis for quantitation. ABO chimerism was quantitatively estimated with detection as low as 0.1 percent. ABO variants showed different patterns of agglutination and nonagglutination. The reconstitution status of the erythroid lineage after ABO-mismatched HPCT was also quantitatively evaluated. A modified coil planet centrifuge method is established by which ABO chimerism could quantitatively be analyzed and ABO variants identified to the same degree of accuracy as the other differential methods and flow cytometry. The monitoring of ABO chimerism might also help the diagnosis of early relapse or rejection after ABO incompatible HPCT.