DETECTION OF MINIMAL RESIDUAL DISEASE USING CLONOSPECIFIC PRIMERS FORCDRIII IN PATIENTS WITH ACUTE B-LYMPHOCYTIC-LEUKEMIA WITH OR WITHOUT PHILADELPHIA-CHROMOSOME - POSSIBILITY OF CLINICAL-APPLICATION AS A TOOL FOR IMPROVING PROGNOSIS

We attempted to identify the minimal residual leukemic clone as relate d to the clinical course in patients with acute B lymphocytic leukemia (B-ALL). DNA was extracted from stored bone marrow slides, and the th ird complementarity determining region (CDRIII) was amplified by polym erase chain reaction (PCR) using primers with consensus sequences for V-H and J(H). After amplification of the CDRIII band, the DNA fragment of CDRIII was inserted into the cloning vector PUC118. After cloning, the DNA sequences for CDRIII were determined. Clonospecific DNA seque nces in CDRIII were selected, and clonospecific primers for each patie nt were synthesized. Using the clonospecific primers, we carried out s econd-round PCR to detect minimal residual disease (MRD) during severa l stages of the clinical course. Basically, the sensitivity of detecti on for MRD was between 10(-4) and 10(-5) cells. Even when leukemic cel ls were not detected in the morphologic study, with this detection sys tem, the MRD was identified as an amplified CDRIII band stained with e thidium bromide on agarose gel. After bone marrow transplantation (BMT ), MRD was detected for at least 4 months. In this article, we discuss the difference in sensitivity of detection for MRD between the BCR-AB L fusion gene and CDRIII in Philadelphia chromosome-positive (Ph(+)) B -ALL, as well as the possible clinical application of this method to p redict relapse and prognosis.