Analysis of mixed chimerism in patients after allogeneic stem cell transplantation using a capillary electrophoresis...

We analyzed mixed chimerism (MC) after allogeneic stem cell transplantation (SCT) using a capillary electrophoresis system with four kinds of fluorescence-labeled primers for microsatellites (D3S1359, D6S89, ACTBP2, HGH). The sensitivities of all microsatellites were at least 3%. The present method is sufficiently rapid: only 3-4 h are needed to perform all the procedures. For analysis of MC in 30 patients who had undergone allogeneic SCT, heterozygosity of all microsatellites was over 88% and informativeness of ACTBP2 and HGH was over 73%. We analyzed MC using this technique to determine whether it was useful for prediction of the prognosis of 22 patients who had undergone allogeneic SCT. MC was more frequently observed in patients who were treated without total body irradiation (TBI) than in patients who were treated with TBI (p = 0.009). MC was also seen in a larger percentage of patients without acute graft-versus-host disease (p = 0.027). Six patients developed graft failure or relapse among 12 patients with MC. The graft failure or relapse was higher in patients with MC than in patients with complete chimerism (CC) (p = 0.009) especially if they were over 30 years of age (p = 0.0005). In contrast, graft failure or relapse was not higher in patients with MC compared with patients with CC under 30 years of age (p = 0.78). These results show that MC is an important predictive factor, especially in patients over 30 years of age.