Minimal residual disease in murine B-cell leukemia (BCL1) detected by PCR

Small proportions of leukemic cells escaping chemo-radiotherapy and/or dormant leukemic cells present in undetectable amounts in patients post therapy, i.e. minimal residual disease (MRD), are a source for relapse. The study of MRD and its treatment in a murine model for human B-cell leukemia/lymphoma, (BCL1), should lead to an improved understanding of the human disease. The standard assay for MRD in experimental mice is the adoptive transfer of spleen cells from experimental animals into naive secondary syngeneic recipients. We describe here the detection of MRD in BCL1-carrying BALB/c mice using the polymerase chain reaction (PCR). A BCL1 specific sequence from the rearranged VH-region was amplified yielding a 456 bp long fragment. PCR products hybridized to the cloned BCL1 sequence allowed the detection of a single BCL1 cell. This assay, therefore, reveals the presence of very small numbers of leukemic cells without sacrificing experimental animals.