[An analysis of leukocyte subsets chimerism following allogeneic peripheral blood stem cell transplantation]

To analyse the relationship of T lymphocyte and granulocyte chimerism following allogeneic peripheral blood cell transplantation and the occurrence of relapse, graft failure and graft versus host disease.

21 patients underwent allogeneic peripheral blood stem cell transplantation (allo-PBSCT). Fluorescence-activated cell sorter (FACS) sorted CD3+ T lymphocytes and CD15+ granulocyte from peripheral blood of all the patients were analyzed for short tandem repeats in 7 days interval for 1 month starting from the day of PBSCT, then 1 month interval for 6 months, and then 3 months interval to the end of one year.

Chimerism of granulocyte was higher than T lymphocyte on day 7 posttransplant in 4 patients given myeloablative conditioning. The median donor chimerism of granulocyte and T lymphocyte was 95% and 55% respectively. The other 17 patients had higher chimerism of T lymphocyte than granulocyte on day 7, which was 60% (15%-76%) and 0% (0%-40%) respectively. 20 patients reached complete donor chimerism (CDC) on day 21 (14-102 days) for T lymphocyte and on day 14 for granulocyte, except one relapsed on day 28. Seven patients had decreasing mixed chimerism when disease relapsed or graft failure occurred. T cell donor chimerism decreased earlier than myeloid cells, however, bone marrow sample and granulocyte still remained in complete donor chimerism or stable mixed chimerism, bone marrow smear showed normal at the same time.

Blood leukocyte subset chimerism analysis, especially T cell chimerism analysis may provide earlier information of engraftment, relapse and graft failure than blood and bone marrow samples, therefore immunomodulatory therapies may be given to recipients earlier and overall survival may be improved.