Southern blot patterns, frequencies, and junctional diversity of T-cell receptor-δ gene rearrangements in acute lymphoblastic leukemia

Abstract

Southern blot analysis of T-cell receptor (TCR)-δ gene rearrangements is useful for diagnostic studies on the clonality of lymphoproliferative diseases. We have developed 18 new TCR-δ gene probes by use of the polymerase chain reaction (PCR) techniques. Application of these probes for detailed analysis of the TCR-δ genes in normal control samples, 138 T-cell acute lymphoblastic leukemias (T-ALL), and 91 precursor B-ALL allowed us to determine the TCR-δ gene restriction map for five restriction enzymes, as well as the Southern blot restriction enzyme patterns of all theoretically possible TCR-δ gene rearrangements. Based on this information, it appeared that 97% of all 213 detected TCR-δ gene rearrangements in our series of ALL could be detected by use of the TCRDJ1 probe and that the majority (76%) of the 213 rearrangements could be identified precisely. In T-ALL, we found a strong preference for the complete rearrangements Vδ1-Jδ1 (33%), Vδ2-Jδ1 (10%), and Vδ3-Jδ1 (7%) and the incomplete rearrangement Dδ2-Jδ1 (11%). In precursor B-ALL, the majority of rearrangements consisted of Vδ2-Dδ3 (72%) and Dδ2-Dδ3 (10%). The junctional diversity of these 6 preferential TCR-δ rearrangements was analyzed and showed an extensive junctional insertion (∼30 nucleotides) for complete Vδ-Jδ rearrangements, whereas incomplete rearrangements had correspondingly smaller junctional regions. The detailed TCR-δ gene restriction map and probes presented here, in combination with the Southern blot patterns of TCR-δ gene rearrangements, are important for TCR-δ gene studies in ALL; all TCR-δ gene rearrangements can be detected and the majority can be identified precisely. Identification of rearrangements is a prerequisite for subsequent PCR analysis of TCR-δ gene junctional regions, eg, for detection of minimal residual disease during follow-up of ALL patients. © 1993 by The American Society of Hematology.