Detection of the sensitivity of the Igκ gene rearrangement. DNA from monoclonal B cell (CLL) was serial diluted (0.5, 0.5 × 10−1, 0.5 × 10−2, 0.5 × 10−3, 0.5 × 10−4, 0.5 × 10−5 μg/sample) with DNA from a reactive tonsil and subjected to FR3Jκ PCR amplification. PCR products were separated using 6% ndPAGE. A distinct PCR band could be identified in the dilution up to 0.5 × 10−3, which represented 0.05% of the total DNA.