Comparison of tube and gel red blood cell agglutination techniques in detecting chimeras after major ABO-mismatched allogeneic hematopoietic stem cell transplantation.

We compared the ability of tube and gel red blood cell (RBC) agglutination techniques to follow erythroid engraftment in a patient who received a major ABO-mismatched peripheral blood stem cell transplant and bone marrow transplant. Tube and gel RBC agglutination techniques were used to detect mixed-field reactivity in cell mixtures containing A/O and c+/c- RBCs and the ability of these two technologies to detect RBC chimeras were compared. We detected c+ RBCs in c+/c- RBC populations microscopically at 1% by the tube RBC agglutination technique, but not until 10% by the gel technique. Group A RBCs in A/O RBC populations were detected at 10% by both techniques. In the patient studied, group A RBCs and c+ RBCs were detected on Days 20 and 14, respectively, with the tube RBC agglutination technique, but neither marker was detected until Day 26 with the gel technique. Tube and gel RBC agglutination techniques comparably identified ABO mixed fields. Although the tube RBC agglutination technique showed greater sensitivity than the gel technique in detecting the c antigen, the gel technique was easier to use and allowed more reliable interpretation of mixed fields by the technologist.