Detection of T cell receptor delta gene rearrangements in childhood B and T lineage acute lymphoblastic leukaemia by southern blot and PCR: technicalcomparison of two methods of analysis

Molecular analysis of antigen receptor genes (Ig and TCR) has been useful f or clonal studies in acute lymphoblastic leukaemia (ALL) patients. Rearrang ements of these genes can be used to track the persistence of the leukaemic clone during the therapy. The purpose of our study was to analyse the perc entage and the pattern of the rearrangements at the TCR D locus in a series of ALL patients, comparing the results obtained by Southern blot and PCR. Genomic DNA was extracted from mononuclear BM cells of 40 paediatric ALL ca ses, digested with different restriction enzymes and hybridized to TCRDJ1 p robe to study the TCR delta locus. Amplification of the rearranged TCR delt a genes was performed by PCR to define the gene segments involved. The junc tional region was deduced from the sequence to obtain patient-specific prim ers. Among the 31 B lineage ALL samples, one or two TCR delta alleles prove d to be rearranged in 53% of cases. Two different types of rearrangements w ere chiefly detected: V delta 2D delta3 and D delta 2D delta3. In T-ALL pat ients, the predominant rearrangement involved the V delta1 and the J delta1 gene segments.