[Evaluation of hematopoietic chimerism after allogeneic bone marrow transplantation by modern molecular techniques (STR-PCR and RQ-PCR)--single center].

Allogeneic hematopoietic stem cell transplantation (alloSCT) is a curative treatment for many patients suffering from malignant and non-malignant hematological disorders. Successful transplantation is a process that requires the engraftment of transplanted pluripotent hematopoietic stem cells which re-establish normal hematological and immunological systems. Distinguishing between host and donor origin of bone marrow and blood cells is vitally important for monitoring of the engraftment process. One of the most useful tools for engraftment monitoring is the assessment of hematopoietic chimerism. Which occurs after alloHSCT and describes the percentage of donor hematopoietic and lymphoid cells in a transplant recipient. 38 adult patients, after alloSCT performed in Katedra i Klinika Hematologii Collegium Medicum UJ entered the study and the total number of transplantations was 43. The evaluation of hematopoietic chimerism was based on PCR amplification of polymorphic non-coding DNA sequences--short tandem repeats (STR-PCR). The main tool was a semiquantitative method--fragment length analysis. The product of amplification was analyzed using the sequencer. The second method was based on a quantitative Real Time PCR technique (RQ-PCR) based on SYBRgreen chemistry. There were performed amplification of biallelic non-coding DNA sequences with short insertions or deletions. Hematopoietic chimerism evaluations were performed on +30, +60, +90, +120, +150, +180, +270 and +360 day and then every 6 months post alloSCT on peripheral blood or bone marrow samples. STR-PCR and RQ-PCR chimerism assays were compared and results evidenced the greater sensitivity of RQ-PCR method. There were not crucial differences in the results of chimerism evaluation obtained by means of these two methods. The analysis of chimerism kinetics after allogeneic stem cell transplantation allowed to modify the post-transplantation-treatment in 3 patients after alloNMSCT leading to increase of donor-origin hematopoiesis in transplant recipients (in 2 pts decision of DLI, 1 of them withdrawal of immunosuppression, 1 pt giving G-CSF). The results of chimerism monitoring confirmed that the failure of achieving a CC or lost of CC can predict the relapse of the disease.