Repetitive DNA polymorphisms in following chimerism after allogeneic bone marrow transplantation

Information about the chimeric status of patients is of great importance in comparison of different conditioning and prophylactic regimens as well as for the post-bone marrow transplantation (BMT) therapies. In some cases, mixed chimerism (MC) can also be predictive of relapse. Analysis of the short tandem repeats (STR) loci by polymerase chain reaction (PCR) is a choice method for this purpose. In this study, we monitored 15 patients after BMT. Twelve of them underwent classical-conditioning regimen while the remaining three patients were subjected to non-myeloablative conditioning (minitransplantation). Evaluation of chimerism was performed using five STR and one variable number of tandem repeats (VNTR) locus. Four additional loci were PCR-amplified in cases of minitransplantation. Samples were analyzed by electrophoresis in an ALFexpress sequencer. MC was detected in seven cases of which it was predictive of relapse for two patients, who suffered from acute lymphocytic leukemia (ALL). The PCR-STR method proved to be a fast and relatively simple method, while the tested STR loci showed a high level of informativeness.