A common Vδ2—Dδ2—Dδ3 T cell receptor gene rearrangement in precursor B acute lymphoblastic leukaemia

Despite their apparent commitment to the B lymphocytic lineage, human precursor B cell acute lymphoblastic leukaemias (ALL) frequently rearrange their T cell antigen receptor (TCR) alpha, beta and gamma chain genes. Since these three genes are active sites of rearrangement in precursor B cell neoplasms, it seemed that the recently discovered fourth TCR gene, delta, might be similarly rearranged. To investigate this possibility, a series of precursor B cell leukaemias was analysed for rearrangements at the delta chain gene locus, using probes of the variable, joining, and constant regions of the delta chain gene. The majority of precursor B cell ALLs in this series (25/32, 78%) showed rearrangement or deletion of one or more TCR delta genes. This contrasts sharply with a series of 16 mature B cell neoplasms (chronic lymphocytic leukaemia) in which no TCR delta gene rearrangements were detected. An unusual TCR delta rearrangement, rarely observed in normal or neoplastic T cells, was seen in the majority (14/18) of precursor B cell ALLs with TCR delta rearrangements. In contrast to the utilization ov V delta 1 in T cell ALL, detailed restriction mapping of precursor B ALL revealed an incomplete rearrangement without involvement of J delta segments. Direct genomic sequencing was performed on one example and demonstrated a nonproductive V delta 2-D delta 2-D delta 3 recombination in this precursor B ALL. We conclude that the TCR delta chain gene is an active locus in precursor B cell neoplasia, involves an unusual type of rearrangement and provides a clonal tumour marker for diagnosis of precursor B ALL.     

Rearrangements of T-cell antigen receptor delta chain gene in hematologic neoplasms

Rearrangements of the T-cell antigen receptor (TCR) delta chain gene were studied in primary neoplastic cells from 137 patients with leukemia or lymphoma. TCR delta gene rearrangements or deletions were observed in all 50 T-cell neoplasms: 5 of 8 CD3- T-cell neoplasms showed rearrangements, whereas biallelic deletion of TCR delta gene was the most common pattern in CD3+ T-cell neoplasm (39 of 42 patients). Rearrangements of TCR delta gene were also detected in 23 of 40 immature B-cell leukemias, including 22 of 25 patients with rearrangements of TCR gamma gene, 2 of 17 mature B-cell neoplasms, and 3 of 30 myeloid leukemias. Thus, TCR delta gene rearrangement or deletion is always found in T-cell neoplasms and is frequently found in immature B-cell leukemias associated with TCR gamma gene rearrangement. Furthermore, TCR delta gene rearrangements associated with the germline configuration of the TCR beta, gamma, and immunoglobulin heavy chain genes were observed in two immature T-cell leukemias, suggesting that TCR delta gene rearrangements precede TCR gamma and beta gene rearrangements. These results indicate that an analysis of TCR delta gene rearrangement provides potential tools to establish the clonality of immature T-cell neoplasms and to identify the normal stages of lymphocyte differentiation.     

High prevalence of T-cell receptor V delta 2-(D)-D delta 3 or D delta 1/2-D delta 3 rearrangements in B-precursor acute lymphoblastic leukemias

Rearrangement of the immunoglobulin (Ig) and T-cell receptor (TcR) genes generally has been considered a useful marker of B- and T-cell lineage in lymphoproliferative disorders. However, concomitant rearrangements of Ig and TcR genes have been commonly reported in the most immature lymphoid malignancies, mainly in B-cell precursor acute lymphoblastic leukemia (ALL). To better characterize the nature of this lineage promiscuity, we have analyzed the configuration of the TcR delta locus in 75 B-precursor ALL. The large majority of cases (87%) displayed a rearrangement or deletion at the delta locus. Among the 57 nondeletional rearrangements, two patterns were predominant and both appeared to derive from partial joining: a V delta-(D)-D delta 3 (32/57) and a D delta 1/2-D delta 3 (11/57) type. A single V delta gene (V delta 2) appeared to be involved in the first type of rearrangement. These findings are at variance with T-ALL, where rearrangements 5' to V delta 2 are usually found. It remains to be elucidated whether this incomplete attempt of V delta 2 gene assembly is related to the neoplastic event or represents a physiologic predisposition occurring during early stages of the normal lymphocyte differentiation.     

Crosslineage TCR delta rearrangements occur shortly after the DJ joinings of the IgH genes in childhood precursor B ALL and display age-specific characteristics

In order to test the hypothesis that the most immature T-cell receptor (TCR) rearrangements occur after the DJ joining of the immunoglobulin heavy chain genes (IgH), we analysed the TCR Vδ2–Dδ3 rearrangements in precursor B-cell leukaemias (PBC ALL) from 25 children younger than 3 years at disease onset and found that most of the junctional regions had N nucleotides inserted. We then selected 14 of these PCB ALLs for DJH (DJ joining of the IgH) characterization. These joining regions showed homology-directed recombination and lack of N regions, indicating absence of terminal deoxynucleotidyl transferase (TdT) activity during their rearrangement. Most leukaemias with a DJH rearrangement without N region have no, or only one, nucleotide in the joining regions of their Vδ2–Dδ3 rearrangements. The N regions of the TCR delta rearrangements displayed 'age-specific' differences: in children younger than 3 years of age the N regions were shorter than in those older than 3 years, and the rearrangements frequently contained complete segments. We conclude that the Vδ2–Dδ3 rearrangement in childhood PCB ALLs is an early event following DJH rearrangement and that it occurs shortly before or after the first hit, leading to malignant transformation.     

Provocative pattern of rearrangements of the genes for the gamma and beta chains of the T-cell receptor in human leukemias.

To examine the distribution of rearrangements of the gamma- and beta-chain T-cell receptor (TCR) genes in T- and non-T acute lymphoblastic leukemias (ALLs), and potentially to determine which genes rearrange first in ontogeny, we analyzed high molecular weight DNA from 102 patients with acute leukemia. Rearranged gamma- and beta-chain genes were found in all T-cell ALLs (22/22) examined. Overall, 27% (18/66) of B-lineage ALLs had beta-chain gene rearrangements, and 41% (24/58) had gamma-chain gene rearrangements, but the distribution of rearranged genes varied according to the stage of B-cell differentiation. The gamma-chain genes were rearranged in 11% (1/9) of the B-lineage patients negative for the common acute lymphoblastic leukemia antigen (cALLA) and 50% (23/46) of cALLA+ ALL patients, while the beta-chain genes were not rearranged in any of the 7 cALLA- ALL patients examined but were rearranged in 32% (18/56) of the cALLA+ patients. Neither TCR gene was found to be rearranged in acute nonlymphoid leukemia patients (0/12) or in patients with B-cell (surface immunoglobulin-positive) leukemia (0/3). Of the 44 cALLA+ patients in which a direct comparison of gamma- and beta-chain gene rearrangements could be made, 34% had both genes rearranged, 16% had only gamma-chain gene rearrangements, and the remaining 50% had both genes in the germ-line configuration. beta-Chain rearrangements have not been found in the absence of gamma-chain rearrangements, thus supporting a proposed hierarchy of TCR gene rearrangements. A provocative finding was that only a small percentage (11%) of the patients with cALLA- B precursor cell ALLs had rearranged TCR genes, while 50% of the cALLA+ leukemia patients had at least gamma-chain rearrangement, raising a question as to whether indeed cALLA- cells are precursors to cALLA+ cells. Interestingly, 18% (2/11) of the cytoplasmic immunoglobulin (cIg)-positive cALLA+ (pre-B) ALLs involved TCR gene rearrangements, compared to 60% (21/35) of the cIg-negative cases, suggesting the possibility that the majority of functional B cells are derived from the cALLA+ pool that contains immunoglobulin but not TCR gene rearrangements.     

T-cell receptor delta gene recombination in common acute lymphoblastic leukemia: preferential usage of V delta 2 and frequent involvement of the J alpha cluster

A high frequency (greater than 80%) of acute lymphoblastic leukemias (ALL) exhibit a recombination of the T-cell receptor (TCR) delta chain locus. Interestingly, distinct TCR delta elements are preferentially used in immunologic subtypes. In a recent series of 201 children with common ALL (cALL) we observed a TCR delta rearrangement in 162 patients, 57% of the latter showing a hybridization pattern in Southern blots suggestive of a V delta 2 to D delta 3 recombination. To verify this interpretation and to elucidate in more detail the diversity of this common type of TCR delta recombination we amplified and sequenced the junctional region of nine cALL patients and cell line REH-6 by polymerase chain reaction (PCR). A V delta 2 D delta 3 recombination was confirmed in all cases; convincing evidence for the participation of D delta 1 or D delta 2 elements was not obtained. Eight of nine patients and REH-6 showed complete 5' D delta 3 boundaries within V delta 2 D delta 3 segments, a limitation of junctional diversity also detected in 50% of peripheral blood cell clones derived from two healthy probands. Notably, sequence identity at the V delta 2 D delta 3 junction was demonstrated for a cALL and one of the control clones. Another group of 35 of 162 cALL patients was characterized by V delta 2 rearrangements and biallelic deletion of J delta and C delta sequences. Using a J alpha consensus primer, PCR-directed sequence analysis demonstrated V delta 2 D delta 3 J alpha recombinations in all four cases analyzed by this approach. The J alpha segments of these patients differed, but were identical or homologous to published J alpha elements. Our data suggest a recombination pathway of the TCR delta/alpha locus leading to chimeric TCR alpha molecules, containing V delta and, remarkably, also D delta sequences.     

Frequent ongoing T-cell receptor rearrangements in childhood B- precursor acute lymphoblastic leukemia: implications for monitoring minimal residual disease

Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL.     

Multiplex PCR for TCR delta rearrangements: a rapid and specific approach for the detection and identification of immature and mature rearrangements in ALL

The preferential occurrence of immature T-cell receptor (TCR) δ rearrangements (i.e. incomplete Dδ2-Dδ3 and Vδ2-Dδ3) in B-cell precursor acute lymphoblastic leukaemia (BCP ALL) and of predominantly mature rearrangements (incomplete Dδ2-Jδ1, complete Vδ1, Vδ2, Vδ3 to Jδ1) in T-lineage ALL prompted us to establish two separate multiplex PCR systems for the identification of clonal TCRδ rearrangements. PCR products of the expected size for the specific rearrangements were detectable from a dilution of 100–1000 clonal cells in 150 000 polyclonal cells. Both multiplex PCR systems were used to analyse samples from 86 childhood BCP ALLs and 30 T-lineage ALLs. The results of the multiplex PCRs were controlled by standard PCR analyses for the individual rearrangements and Southern blots, which were identical. Only immature TCRδ rearrangements were detected in BCP ALL (59%), whereas no rearrangement was found in the remaining BCP leukaemias, thus confirming the exclusive presence of immature TCRδ rearrangements in B-lineage cells. 50% of the T-lineage ALLs contained mature rearrangements, but no immature rearrangements were found. These two multiplex PCR techniques appear to be reliable and fast aids in the analysis of clonal TCRδ rearrangements in ALL.     

Disruption of the SCL locus in T-lymphoid malignancies correlates with commitment to the T-cell receptor alpha beta lineage.

The SCL/tal-1 gene on chromosome 1 is disrupted in up to 30% of immature T-cell malignancies, thus representing the most commonly recognized chromosomal abnormality in this disorder. Abnormalities of the gene occur rarely by chromosomal translocation into the T-cell receptor (TCR) delta locus and commonly by a site-specific 95-kb deletion, SIL-SCL (tald). Analysis of the SIL-SCL deletion by Southern blotting and polymerase chain reaction (PCR) in a series of 52 immature T-cell malignancies showed a type A deletion in 21% of cases, but no type B deletions. The type A deletion correlated with malignancies of the TCR alpha beta lineage, either on the basis of TCR alpha beta expression or bilateral TCR delta deletion. Fifty percent (5 of 10) of TCR alpha beta-expressing cells demonstrated the abnormality, whereas 0% (0 of 11) of TCR gamma delta-expressing cells did so. Six of eight SIL-SCL type A cases had undergone bilateral delta deletion, whereas only one of 31 cases with an apparently normal SCL gene had done so. These data demonstrate an association between SCL disruption and TCR alpha beta lineage differentiation and suggest that the SIL-SCL deletion occurs at the same stage of ontogeny as TCR delta deletion.     

Developmental process of the T-cell receptor α and δ gene assembly in B-cell precursor acute lymphoblastic leukaemia

We analysed the organization of V delta genes and delta recombining element (delta Rec) in 27 children with B-cell precursor acute lymphoblastic leukaemia. Twenty-two of 54 alleles showed rearrangements of the T-cell receptor (TCR) delta locus. These rearrangements resulted either from D2D delta 3 (2 alleles) or V delta 2(Dn)D delta 3 (20 alleles) recombinations, and the other V delta and delta Rec were not rearranged. Of 23 alleles with deletion of C delta and rearrangements of J alpha, V delta 2, V delta 4 and V delta 5 appeared to rearrange to J alpha on five alleles. With regard to the relationship between the rearranged V alpha/delta and J alpha genes, gene segments 5' to V delta 2 frequently rearranged to J alpha more proximal to C alpha, whereas V delta 2 and gene segments 3' to V delta 2 showed a tendency to rearrange to J alpha distal to C alpha. Based on these findings, we suggest that the initial recombination event of the TCR-alpha/delta gene may be D2D delta 3 joining, followed by V delta 2 recombination with the D2D delta 3 complex. It was also suggested that use of V alpha/delta and J alpha/delta may depend on the distance between the involved V alpha/delta and J alpha/delta at least in B-lineage cells. These rearrangements in B-precursor cells appear to be aberrant. However, this recombinational process may be one of the normal differentiation pathways in T-lineage cells, because cells with a V delta 2(Dn)D delta 3 rearrangement were detected in 0.1-0.01% of normal peripheral mononuclear cells by the polymerase chain reaction.     

A new case of acute lymphoblastic leukemia B-cell type with chromosomal rearrangements involving the T-cell receptor breakpoint at band 14q11.

A patient with B-cell acute lymphoblastic leukemia (ALL) and a translocation t(8;14) (q24;q11) is described. Translocation t(8;14)(q24;q32) is commonly associated with B-cell leukemia; nevertheless, translocations affecting chromosome 14 at band q11 are associated with T-cell malignancies, since the locus 14q11 contains genes that encode for the alpha and delta chains of the T-cell receptor (TCR). This finding points to the idea that the association between 14q11 rearrangements and T-cell neoplasia is less than complete.     

Gamma/delta lineage relationship within a consecutive series of human precursor T-cell neoplasms

We analyzed the gene rearrangements associated with the newly described delta T-cell receptor (TCR) gene from a series of 19 consecutive precursor T-cell (lymphoblastic) neoplasms that represent discrete stages surrounding the TCR gene rearrangement process. Significantly, the delta TCR gene showed rearrangement in most (13 of 19) of these T cells, and in addition it was rearranged in two cells displaying no rearrangement for any other TCR gene. Our survey showed three types of delta gene rearrangements associated with cell-surface TCR expression that presumably represent usage of three V delta genes. This analysis demonstrates (1) a major subclass of human precursor T-cell neoplasms belonging to the gamma/delta T-cell receptor-rearranging subtype; (2) a narrow repertoire of human V delta gene usage; and (3) the utility of delta gene rearrangements as a diagnostic clonal marker in precursor T lymphoblastic neoplasms.     

Immunogenotyping with antigen receptor gene probes as a diagnostic tool in childhood acute lymphoblastic leukaemia

13 cases of childhood acute lymphoblastic leukaemia (ALL) were studied combining cell surface marker analysis with immunogenotyping by Southern blot hybridisation with a panel of antigen receptor gene probes. The immunophenotypes were unequivocal: 7 patients had B-phenotype and 6 patients T-phenotype ALL. In several patients immunogenotypes were not fully consistent with the respective phenotypes. For example, 2 B-cell precursor ALL had rearranged TCR beta chain genes and 2 T-ALL rearrangement of Ig heavy-chain genes. All cases showed clonal rearrangement or deletions within the TCR delta gene locus. TCR delta gene rearrangements might, therefore, serve as markers of clonality but not of B- or T-lineage in immature lymphoid neoplasms. We conclude that in current diagnostic practice immunogenotyping is a supplement rather than an alternative to immunophenotyping by surface marker analysis.     

Unusual T-cell receptor-delta gene rearrangement patterns revealed by screening of a large series of childhood acute lymphoblastic leukaemia by multiplex polymerase chain reaction

Rearrangements of the T-cell receptor (TCR) and immunoglobulin genes are considered as useful clonal markers in lymphoproliferative disorders of B- and T-cell lineage, and are frequently used for the detection of minimal residual disease (MRD). In this paper, we report on the unexpected results of an extensive analysis of TCR-delta chain gene rearrangement frequencies and patterns in leukaemic bone marrow DNA samples collected from 438 children with initial (n = 112) or relapsed (n = 326) acute lymphoblastic leukaemia (ALL). By applying a previously described multiplex polymerase chain reaction, the overall incidence of non-deleted TCR-delta gene rearrangements in ALL was 47% (206/438), 52% in initial ALL (58/112) and 45% in relapsed ALL (148/326). As expected, the majority of B-cell precursor (BCP) ALL had incomplete Vdelta2-Ddelta3 or Ddelta2-Ddelta3 TCR-delta gene rearrangements, whereas most T-ALL showed complete rearrangements of the TCR-delta gene locus (Vdelta1-Jdelta1, Vdelta2-Jdelta1, Vdelta3-Jdelta1). However, unexpectedly, 5/206 rearranged TCR-delta alleles in BCP-ALL showed a complete Vdelta-(Ddelta)-Jdelta gene rearrangement pattern, and 3/31 T-ALL had an incomplete recombination. Theoretically, complete TCR-delta gene rearrangements should not occur in cells other than T-lymphocytes and have only been reported once previously in BCP-ALL. The data contribute to the discussion about the reliable screening for clonal markers in ALL.     

Immunoglobulin and T-cell receptor gene rearrangement and expression in human lymphoid leukemia cells at different stages of maturation.

The use of probes to genes (IG and TCRB) encoding immunoglobulins (IG) and the beta chain of the T-cell antigen receptor (TCRB), respectively, have become a sensitive means to assess clonality and lineage in lymphoid malignancies. It has become apparent that some individual cases show rearrangements of both IG and TCRB genes. In an attempt to more accurately define cell lineage we have analyzed cells from patients with B- or T-cell leukemia (n = 26) at various stages of maturation with probes to two additional TCR genes, TCRG and TCRA (encoding the TCR gamma and alpha chains, respectively), as well as the IG heavy chain joining region (IGHJ) and TCRB genes. On Southern blot analysis, the mature T-cell leukemia cells studied had rearranged TCRG and TCRB while IGHJ remained as in the germ line. The mature B-cell leukemia cells studied had rearranged IGHJ with germ-line TCRG and TCRB. These data suggest that, in the majority of more mature leukemias, cells have rearranged IG or TCR genes but not both. In contrast, cells from five of nine precursor B-cell leukemia patients and cell lines from one of four precursor T-cell leukemia patients had rearranged both IGHJ and TCR genes. TCRG and TCRB mRNAs were expressed in the cells of precursor T- but not B-cell leukemia patients studied. The spectrum of leukemia cells studied within the T-cell series permitted an assessment of the order of TCR gene rearrangements. Two of 13 patients had cells with germ-line TCRG and TCRB, 2 patients had cells with rearranged TCRG alone, and the remainder had cells with rearranged TCRG and TCRB. TCRG and TCRB mRNAs were expressed in precursor T-cell leukemia cells, whereas TCRB and TCRA were expressed in mature T-cell leukemia cells. These results parallel observations from mouse studies on gene expression and support the view of a hierarchy of TCR gene rearrangements in T-lymphocyte ontogeny. TCRG genes are rearranged first, subsequently TCRB genes are rearranged, followed by TCRA gene activation.