[Development of multiplex short tandem repeat (STR)-PCR for chimerism analysis in patients with hematological malignancies and comparison of chimerism in different sample sources].

Polymerase chain reaction analysis of short-tandem repeat (STR) markers (STR-PCR) has been used for chimerism testing to assess engraftment following hematopoietic stem cell transplantation (HSCT). We investigated the informativity of 7 STR loci (FGA, D5S818, SE33, TH01, VWF, PentaE, and D18S51) in 82 pre-HSCT DNA samples from 41 donor/recipient pairs and developed 2 multiplex STR-PCRs using VWF, SE33, and D18S51, D5S818 and FGA, respectively. The multiplex STR-PCRs could distinguish the recipients and donors in 92.7% of the cases. Dilution experiments using mixed DNA showed that the sensitivity of the multiplex STR-PCRs for detecting the minor population was 1-5%. To compare chimerism in different samples such as peripheral blood, mononuclear cells (MNC), and CD3-positive cells (CD3+), we investigated the relationship between the chimerisms at approximately day 30 post-HSCT and the interval from the day of HSCT to achievement of complete chimerism (CC) in 70 patients undergoing HSCT. CC was found in all samples of 54 patients at day 30 post-HSCT, and these samples showed CC thereafter. Eleven patients with mixed chimerism (MC) in all samples or in MNC and CD3+ showed CC at day 60-270 post-HSCT or persistent MC. The remaining 5 patients with MC in only CD3+ showed CC at day 30-60 post-HSCT. Taken together, MNC which can be separated easily may be a useful source for detecting patients who require longer time to achieve CC and those with high risk of graft failure.