Size and composition of T-cell receptor delta (TCRD) junctional sequences are not predictive of the sensitivity of clonospecific oligonucleotides designed for detection of minimal residual disease in acute lymphoblastic leukemia.

We characterized 168 junctional regions of T-cell receptor delta (TCRD) rearrangements from 116 children with acute lymphoblastic leukemia (ALL) (101 with precursor B-cell ALL, 15 with T-cell ALL). Application of 101 allele-specific oligonucleotide (ASO) probes representing 85 Vdelta2Ddelta3, 10 Ddelta2Ddelta3, 3 Vdelta1Jdelta1, 1 Vdelta3Jdelta1, and 2 Ddelta2Jdelta1 junctions for the detection of minimal residual disease (MRD) revealed detection levels of 10(-4) to 10(-6) leukemia cells in the vast majority of cases (93 of 101). Of interest was that neither the N, D, P (nontemplated, diversity, palindromic) content and length of the junctional regions nor the number of nucleotides deleted from the flanking V, D, or J (variable, diversity, joining) elements correlated with the sensitivity of ASO probes. These data indicated that in ALL TCRD rearrangements can serve as suitable tools for the detection of MRD irrespective of the specific composition of the junctional region.