ABSTRACT
More sensitive techniques are required for the detection of low frequencies of malignant cells during and after treatment, i.e., detection of minimal residual disease (MRD). In order to limit the risk of false-negative MRD results due to clonal evolution phenomena, preferably two MRD-polymerase chain reaction (PCR) targets with sufficient sensitivity should be used for each acute lymphoblastic leukemia patient. A potential pitfall of immunophenotypic MRD detection in hematological malignancies is the occurrence of immunophenotypic shifts during the course of the disease. The sensitivity of MRD-PCR analysis of junctional regions is dependent on the type of rearrangement, on the size of the junctional region, and on the “background” of normal lymphoid cells with comparable immunoglobulin/T-cell receptor gene rearrangements. With recently developed high-dose sequential chemotherapy, it is possible to harvest MRD-PCR-negative autologous bone marrow grafts in most follicular lymphomas patients and MRD-PCR-negative autologous peripheral blood grafts in more than half of the patients.
