Kinetics of dendritic cell chimerism and T cell chimerism in allogeneic hematopoietic stem cell recipients.

Dendritic cells (DC) as potent antigen-presenting cells (APC) and T cells as effector cells play an essential role in the pathophysiology of both graft-versus-host (GvH) and graft-versus-leukemia (GvL) reactions after transplantation. Therefore, we determined the kinetics of DC and T-cell chimerism establishment after allogeneic hematopoietic cell transplantation (AHCT) in a group of 144 patients, using fluorescence-activated cell sorting (FACS) or magnetic cell sorting (MACS) followed by FISH or STR-PCR analysis for chimerism evaluation. In all, three cell lines investigated (CD3(+) T cells, CD11c(+) DC1 and CD123(+) DC2), we found a rapid and consistent establishment of complete donor chimerism (CDC) in over 70% of all patients during the first 6 weeks after AHCT. The rate of patients with CDC increased significantly over time within the first year after transplantation. A related donor (P=0.004) as well as an underlying lymphatic leukemia (P=0.03) were found to be significantly associated with development of MC in T cells. No significant correlation between DC or T cell chimerism and GvHD or relapse was detected. Our results thus demonstrate a fast and stable CDC in DC1, DC2 and T cells after AHCT that continuously increases over time in nearly all patients.