Clinical application of gene technology to monitor bone marrow transplantation

We assessed the origin of peripheral blood cells and bone marrow cells obtained from 15 patients after allogeneic bone marrow transplantation (allo BMT) by sensitive two-step polymerase chain reaction (PCR) amplification of MCT118, a variable number of tandem repeats regions (VNTR), that can be used to detect the DNA pattern of a minor cell population of only 1% without using radioisotopes. Mixed chimerism(MC) was detected in the haematopoietic cells of 3 patients. Two patients developed relapse of leukaemia after the detection of MC and one patient died of bone marrow hypoplasia 7 months after BMT. These findings indicate the clinical usefulness of this method to monitor patients with MC. Also, we analyzed cytokine gene expression in peripheral blood mononuclear cells during the development of graft-versus-host disease (GVHD) in patients who underwent allo BMT using a semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR). The expression of interleukin(IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha mRNA was increased during the development of GVHD and the degree of this increment depended on the severity of the disease. These findings suggest that IL-1 beta, IL-6, and TNF-alpha produced by peripheral blood mononuclear cells play an important role in the development of GVHD. Therefore, analysis of MC and cytokine mRNA expression using the PCR technique after allogeneic bone marrow transplantation provide important information for treatment and monitoring of marrow transplant patients.