PCR analysis of TCR/Ig rearrangement
High-molecular weight DNA from marrow cells was initially
screened for major rearrangement patterns of TCRγ,
TCRδ, and Igκ, and secondarily screened for rearrangements
in Ig heavy chain (IgH), using previously described
primers [19-21]. Two-step (nested) PCR for MRD quantification
was performed using allele-specific oligonucleotide
(ASO)-primers based on the sequence of PCR
screening products, which had clonal recombinations by
heteroduplex analyses. Prior to PCR analysis, DNA samples
from post-treatment bone marrow samples and DNA
from the samples obtained at diagnosis were serially
diluted (between 10−2 and 10−5) with buffy coat DNA
from eight healthy volunteers. Buffy coat DNA was also
used as a control for nonspecific amplification of comparable
Ig/TCR arrangements present in normal cells. All
PCR reactions were performed simultaneously and analyzed
using ethidium staining and agarose gel electrophoresis.
MRD was quantified by comparing the intensities of
band signals on an agarose gel stained with ethidium
bromide without amplification of the background. MRD
quantifications were performed using ASO-primers with a
sensitivity of ≤1 × 10−4, and MRD positivity was defined as
a lower limit of detection of ≥1 × 10−3.