Malignant Cell Detection in Burkitt's Lymphoma Using Third‐complementarity‐determining Region (CDRIII), Clone‐specific Probe Developed by Sequencing DNA from Stored Slides

The DNA sequence of the third‐complementarity‐determining region (CDRIII) of the immunoglobulin heavy chain (IgH) gene in a case of Burkitt's lymphoma was determined hy polymerase chain reaction (PCR) using template DNA extracted from a smear stored at room temperature for more than one year. The DNA sequence obtained from the stored slide was compared with that of DNA from a frozen lymph node biopsied at the initial presentation. The sequences were shown to he identical, implying that DNA from a smear on a stored slide can he used as a source of DNA for PCR amplification, sequencing, and development of a clone‐specific probe. Using oligonucleotides generated from one of the CDRIII sequences of the IgH gene as molecular probes, a retrospective study for the malignant clone on the smears was carried out. Malignant ceils were detectable in the peripheral blood at an early stage of hone marrow relapse but not in the peripheral blood or bone marrow at the initial presentation. No malignant clone was detected in the bone marrow when testicular infiltration was diagnosed by examination of a pathological specimen. Thus, the technique permits molecular analysis of hematologic malignancies of B‐cell lineage in cases where fresh or frozen specimens are not available.