OBJECTIVETo evaluate the relationship of chimerism status of cell subsets with engraftment, occurrence of acute graft versus host disease (aGVHD), graft rejection and disease relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODSChimerism status in peripheral blood (PB) and bone marrow (BM) of 65 patients received allo-HSCT were monitored at regular intervals post-transplant. Fluorescence-activated cell sorter (FACS) was used to sort CD3(+)T lymphocytes in 65 cases, CD3(-)CD56(+)CD16(+)NK cells in 52 cases, CD15(+) granulocytes in 32 cases and CD19(+)B lymphocytes in 20 cases post transplants. The chimerism status of different lineage cells was analyzed by polymerase chain reaction amplification of short tandem repeats (PCR-STR).

RESULTSOn day +7, NK-cells donor chimerism (DC 55.5%) was higher than other cell subsets. T lymphocyte was the latest one to reach complete donor chimerism (CDC) with a median on day +21. Patients whose T lymphocytes donor chimerism was more than 70% on day +7 and more than 95% on day +14 had a high risk for acute aGVHD. In all cases except those with ALL, the decreased DC of T lymphocytes were observed before molecular or hematological relapse occurred.

CONCLUSIONSerial and quantitative T cell chimerism analysis provides a reliable and rapid screening method for the early detection of engraftment, graft rejection, disease relapse and occurrence of aGVHD, therefore, is a prognostic tool to identify patients at high risk of aGVHD and disease relapse following allo-HSCT.