Cell Receptor Gamma Chain Genes Research Articles

Effects of fixation and demineralization on histomorphology and DNA amplification of canine bone marrow.

Fixation and demineralization protocols for bone marrow (BM) across diagnostic laboratories are not standardized. How different protocols affect histomorphology and DNA amplification is incompletely understood. In this study, 2 fixatives and 3 demineralization methods were tested on canine BM samples. Twenty replicate sternal samples obtained within 24 hours of death were fixed overnight in either acetic acid-zinc-formalin (AZF) or 10% neutral-buffered formalin (NBF) and demineralized with formic acid for 12 hours. Another 53 samples were fixed in AZF and demineralized with hydrochloric acid for 1-hour, formic acid for 12 hours, or ethylenediamine tetraacetic acid (EDTA) for 24 hours. Histologic sections were scored by 4 raters as of insufficient, marginal, good, or excellent quality. In addition, DNA samples extracted from sections treated with the different fixation and demineralization methods were amplified with 3 sets of primers to conserved regions of T cell receptor gamma and immunoglobulin heavy chain genes. Amplification efficiency was graded based on review of capillary electrophoretograms. There was no significant difference in the histomorphology scores of sections fixed in AZF or NBF. However, EDTA-based demineralization yielded higher histomorphology scores than demineralization with hydrochloric or formic acid, whereas formic acid resulted in higher scores than hydrochloric acid. Demineralization with EDTA yielded DNA amplification in 29 of 36 (81%) samples, whereas demineralization with either acid yielded amplification in only 2 of 72 (3%) samples. Although slightly more time-consuming and labor-intensive, tissue demineralization with EDTA results in superior morphology and is critical for polymerase chain reaction (PCR) amplification with the DNA extraction method described in this article.

Somatic hypermutation introduces a high frequency of amino acid substitutions in the constant region of the T cell receptor alpha chain in ballan wrasse (Labrus bergylta)

It was previously thought that T cell receptor genes were not subject to somatic hypermutation, which is in contrast to immunoglobulin genes where this mechanism is associated with a key role in the affinity maturation of the antibody response. However, recent studies in shark and camels have shown that variable T cell receptor gamma chain genes are hypermutated. In this presentation we show that somatic mutations on the constant part of the T cell receptor alpha chain gene are frequent in a teleost fish; Ballan wrasse (Labrus bergylta). We examined many Tcra cDNAs from the same individual to determine if constant region diversity exceeded the amount that could be attributed to germline polymorphism. It is plausible to assume that somatic hypermutation is involved in the generation of the T cell repertoire and that consequently mutations are introduced in the constant region gene. The amino acid substitutions we found in Ballan wrasse are primarily positioned in the loops between the beta sheets, i.e. regions that apparently are not critical for the overall structure. It has been reported that polymorphism at the constant T cell receptor alpha chain genes is widespread in teleosts. After we had found several amino acid substitutions in translated cDNAs present in public databases the present study was initiated in an attempt to reveal corresponding polymorphism in Atlantic salmon (Salmo salar). Although we sequenced the gene in several individuals from rivers in Norway, Russia and Canada we only found some germline mutations in untranslated regions.

Lupus nephritis class I accompanied by tubulointerstitial nephritis with marked T-lymphocyte infiltration in an HTLV-1 positive patient.

We herein describe the case of a 40-year-old Japanese male who was admitted to our hospital because of a continuous remittent fever lasting 1month. He fulfilled the items of the classification criteria for the diagnosis of systemic lupus erythematosus (SLE). The administration of 20mg per day of oral prednisolone completely diminished his clinical symptoms. However, his renal biopsy performed 1day after the admission showed marked pathognomonic characteristics. Not only did his glomeruli show class I lupus nephritis with mesangial depositions of IgG, IgA, C3, and C1q, but also tubulointerstitial nephritis with marked T-lymphocyte infiltration. These infiltrated T cells partly had nuclear atypia. The patient was positive for human T cell leukemia virus type 1 (HTLV-1) antibodies. Furthermore, clonal rearrangements of T cell receptor-gamma chain gene was detected in the DNA extracted from his kidney sections by the polymerase chain reaction (PCR) method. A second renal biopsy 6months after the prednisolone treatment showed that the infiltrating T lymphocytes had markedly diminished. This is the first case report of lupus nephritis class I with tubulointerstitial nephritis, which might include oncogenic T lymphocytes, in an HTLV-1 positive patient.

Clinical significance of clonality and Epstein‐Barr virus infection in adult patients with hemophagocytic lymphohistiocytosis

We assessed the clinical significance of T or B cell clonality and Epstein-Barr virus (EBV) infection in adult patients with hemophagocytic lymphohistiocytosis (HLH) to identify factors related to prognosis. A total of 30 adult patients with diagnosed HLH were included in the study. In all patients, EBV-DNA in peripheral blood was examined by quantitative real-time polymerase chain reaction and bone marrow cells were examined for clonal rearrangement of T cell receptor gamma(TCRG) and immunoglobulin heavy chain (IGH) genes. TCRG clones were detected in 10 patients (33.3%) and IGH clones were detected in 8 patients (26.7%). We found no correlation between clonality and patient outcome. The patients less than 1,000 copies (mL)21 of EBVDNA showed a significantly higher clinical response (P 5 0.008) and longer overall survival (P 5 0.01) than those with high viral load of EBV-DNA. Our results suggest that TCRG and IGH rearrangement do not have any clinical significance in adult patients with HLH, but that high viral load of EBV-DNA may be a risk factor for poor outcomes. In HLH, high viral load of EBV-DNA should thus suggest a prompt approach with aggressive therapeutic interventions.

Cytotoxic peripheral T cell lymphoma arising in a patient with nodular lymphocyte predominant Hodgkin lymphoma: a case report

In this paper, we describe a case of nodular lymphocyte predominant Hodgkin lymphoma with the subsequent development of a peripheral T cell lymphoma. This case is unusual in that the sheets of atypical and small to intermediate-sized T cells in the diffuse component were CD8 positive and expressed cytotoxic proteins. The diagnosis of peripheral T cell lymphoma was supported by the demonstration of a clonal T cell receptor beta chain gene rearrangement by Southern blot analysis. Peripheral T cell lymphoma with a cytotoxic phenotype is a rare entity with an aggressive clinical behavior. As such, this report emphasizes the need to consider a diagnosis of coexisting peripheral T cell lymphoma in cases of nodular lymphocyte predominant Hodgkin lymphoma with atypical features, such as few or poorly defined B cell macronodules and diffuse T cell areas. The examination of both T cell receptor gamma and beta chain gene rearrangements should be performed to confirm such cases.

Lymphoma-like Lesion of the Uterine Cervix

Lymphoma-like lesion of the female genital tract is rare. We report 12 cases of lymphoma-like lesions of the cervix in patients ranging from 27-54 years of age (mean 41). The commonest clinical presentation was post-coital bleeding (8), which was followed by vaginal bleeding (2) and leukorrhagia (4). Grossly, the lesions were either polypoid (8) or ulcerated (4). On histological examination, the lesions were eroded and involved the superficial mucosa 2-12 mm (mean 4 mm) in depth. They comprised sheets of dense populations of predominantly large lymphoid cells admixed with small lymphocytes, plasma cells, and neutrophils. Follicle formation was occasionally seen. Immunostaining revealed the majority of the large cells were B cells (CD20(+), CD79a(+)) with no aberrant CD5 and CD43 expression. The lymphoid cells in the follicle were CD10(+) and bcl6(+) but negative for bcl-2. Cyclin D1 was negative. There was no immunoglobulin light chain restriction and polymerase chain reaction for T cell receptor-gamma chain gene and immunoglobulin heavy chain gene demonstrated polyclonal patterns. In situ hybridization for EBER and high risk HPV 6/11 and 16/18 were negative. All patients were well with one case developing local recurrence in the follow-up period up to 7 years.

Long-Term Follow-Up of Patients with T-Large Granular Lymphocyte Leukemia (T-LGL); Experience in a Single Institution.

T-LGL is a clonal indolent lymphoid leukemia characterized by accumulation of large granular T-cells and cytopenias. We have identified 21 patients with T-LGL who were seen at the MD Anderson Cancer Center between 1997 and 2005. The median age at diagnosis was 53.5 years (range 34 to 72) without a male or female predilection. Fourteen patients (67%) were asymptomatic at diagnosis. Five patients (24%) presented with fatigue secondary to anemia; 1 (5%) had symptomatic splenomegaly and 1 presented with a diverticular abscess. Eighty percent of the patients presented with anemia with median hemoglobin of 9.9g/dl (range 7.4 to12.9 g/dl), 47% with neutropenia with a median absolute neutrophil count of 975/ul (range 110 to 5600/ul), and 38% had thrombocytopenia with a median platelets count of 61.5 x 109/l (range18 to 135 x 109/l). Six patients (29%) had splenomegaly, 3 (14.2%) had hepatomegaly and 1 had retroperitoneal lymph node enlargement on CT. During the course of follow-up (median 19 months, range 2–78 months), 11 patient (52%) developed constitutional symptoms. Six patients had recurrent infections including upper respiratory infections, pneumonia, and folliculitis unrelated to initiation of treatment. Associated autoimmune conditions included rheumatoid arthritis in 3 patients (14%) and hemolytic anemia in one patient. Only two patients had cytogenetic abnormalities, both including abnormalities involving chromosome 6. Monoclonal T cell receptor gamma chain gene rearrangements were detected by PCR analysis in 17 of 18 evaluable patients. Immunophenotypic studies revealed 16 patients to be CD4−/CD8+, 3 CD4−/CD8−, 1 CD4+/CD8+, and 1 CD4+/CD8−. CD56 was positive in 1 patient and none expressed CD26. Five patients (24%) have required no therapy, and remain asymptomatic with a median follow up of 67 months (range 5 to 78). Three patients received erythropoietin or G-CSF with some improvement. Nine patients (43%) were treated with cyclosporine, 2 achieving a response, 2 with stable disease, 3 with progression, and 2 were lost follow up. One of the 3 patients with disease progression had splenectomy and 1 was treated with infliximab; both responded. Combination of pentostatin and alemtuzumab was used in 2 patients with no improvement in the cytopenias; therapy was discontinued in both due to worsening of cytopenias and infections. Other treatment modalities included alemtuzumab alone in 1 patient with no improvement, fludarabine in 1 with minor response, combination of fludarabine and cyclophosphamide in 1 with minor response, methotrexate in 2 with no response and splenectomy in 3 with response and no requirements for further intervention. We conclude that T-LGL generally has an indolent course with no need for active therapy; patients with progressive cytopenias or refractory disease may benefit from splenectomy. New treatment modalities are needed.

Clonal T cell receptor gamma-chain gene rearrangement by PCR-based GeneScan analysis in the skin and blood of patients with parapsoriasis and early-stage mycosis fungoides.

Cutaneous T cell lymphoma (CTCL) and reactive T cell skin diseases represent opposite ends of a spectrum of diseases ranging from overtly malignant to persistently benign. Within this spectrum, the parapsoriasis group is not clearly defined regarding malignant potential. In contrast to consistent findings in advanced-stage CTCL, clonality analysis of parapsoriasis has produced conflicting results in previous studies. As T cell receptor gamma-chain polymerase chain reaction GeneScan analysis (TCR-gamma-PCR-GSA) stands out by its sensitivity, its accuracy in size determination of PCR products, its capacity to identify false positives by repeated analysis and its easy applicability, this approach was used to analyse the clonality status of 41 patients with borderline T cell lymphoproliferative skin diseases, including parapsoriasis (n=27) and early-stage mycosis fungoides (MF) (n=14). A monoclonal T cell infiltrate was demonstrated by repeated TCR-gamma-PCR-GSA in lesional skin specimens in 19.2% of parapsoriasis patients and in 66.6% of early-stage MF cases (p=0.013). In peripheral blood, a monoclonal T cell population was found in a similar percentage of parapsoriasis and of early-stage MF patients (26.7% versus 12.5%; p=0.611). A detailed analysis of parapsoriasis subentities, namely small and large plaque parapsoriasis, and parapsoriasis lichenoides, revealed monoclonality in 2(6)/2(5), 3(14)/2(8) and 0(6)/0/(3) of the skin and peripheral blood specimens, respectively. The high detection rate of false positive cases by repeated analysis (20-37.5%) provides a corrected perspective for the high rates of dominant T cell clones found by others in the peripheral blood of such patients. From the results obtained, three major conclusions can be drawn: firstly, CTCL is clearly associated with detection of monoclonality, even in its early stages; secondly, monoclonality is not a prerequisite for potential CTCL precursor entities; and thirdly, recirculating malignant T cells identical to the skin clone are not readily detected in parapsoriasis or early-stage MF, but may rather indicate disease progression.

T Cell Receptor γ-Chain Gene Polymerase Chain Reaction to Diagnose Central Nervous System Involvement by Cutaneous T Cell Lymphoma

The authors describe a patient who was suspected of having cutaneous T cell lymphoma involvement of the brain despite repeatedly negative cerebrospinal fluid (CSF) cytology, inconclusive flow cytometry, and no discrete lesion for brain biopsy. The diagnosis was made by polymerase chain reaction (PCR) analysis that showed a monoclonal T cell receptor gamma-chain gene rearrangement in the CSF, identically sized to that present in a skin biopsy specimen. Thus, PCR could be used early and routinely to diagnose central nervous system spread of T cell lymphomas, because of its potentially superior sensitivity and specificity to CSF cytology.

Lymphoid Tissues from Patients with Infectious Mononucleosis Lack Monoclonal B and T Cells

In typical cases of infectious mononucleosis (IM), lymphoid tissue is rarely submitted for pathological examination. When lymphoid tissues from IM cases are examined, the histological appearance of IM may be difficult to distinguish from malignant lymphoma. The purpose of this study was to address the utility of clinical molecular assays for T and B cell clonality in distinguishing IM from lymphoid malignancy. DNA was recovered from paraffin-embedded archival lymphoid tissues of 18 cases of IM and 13 control cases representing other reactive lymphoid hyperplasias. T cell receptor gamma (TCR-gamma) and immunoglobulin heavy chain (IgH) gene rearrangements were assayed using our standard clinical polymerase chain reaction procedures targeting each of the four functional variable (V) families and the three joining (J) families of the TCR-gamma gene, and framework III of the IgH gene, respectively. In 17 of 18 cases of IM, no monoclonal T or B cell populations were detectable. One case, the only spleen specimen in the study, had an oligoclonal pattern of TCR-gamma rearrangements. The control cases representing other reactive hyperplasias also lacked monoclonality. The assays used were sensitive to clonal populations as small as 5% of cells. In this case series, no monoclonal lymphoid populations were identified in any case of IM. This finding suggests that molecular studies are useful in distinguishing IM from lymphoid neoplasms.

Differentiating Lymphoblastic Lymphoma and Ewing's Sarcoma: Lymphocyte Markers and Gene Rearrangement

We encountered a child with an intraosseous small round cell tumor that was negative for LCA, CD20 (L26), and CD3 and positive for vimentin, CD99 (MIC-2), and periodic acid-Schiff. The tumor exhibited rosette-like formations. This case was initially interpreted as Ewing's sarcoma (ES); however, additional studies revealed positivity for CD79a, CD43, and TdT expression, and an immunoglobulin heavy chain gene rearrangement (IgH-R) by polymerase chain reaction (PCR) established this to be a precursor B-lymphoblastic lymphoma. Because the differential diagnosis of ES and lymphoblastic lymphoma can be difficult and the differential diagnostic value of leukocyte antigens and immunoglobulin heavy chain gene rearrangement studies have not been fully evaluated, we conducted a more extensive investigation on 33 (21 soft tissue and 12 intraosseous) ES cases. Cases were retrieved from the files of the Department of Pathology at Georgetown University and from the Soft Tissue Registry of the Armed Forces Institute of Pathology. The cases were studied by light microscopy, immunohistochemistry, and PCR for IgH-R and T cell receptor gamma chain gene rearrangement (Tγ-R). There were 17 females and 16 males; the mean age was 29.3 years. Locations included the extremities (n = 17) and trunk (n = 16). All cases fit the ES spectrum by light microscopy and immunohistochemistry, as previously determined, and were negative for lymphoid markers (LCA, CD3, CD20, CD43, CD79a, and TdT), CD10 and CD34. CD99 was positive in 31/33 and bcl-2 was weakly positive in 13/33 cases. All 21 cases studied for gene rearrangements by PCR were negative for IgH-R and Tγ-R. Distinction of intraosseous lymphoblastic lymphoma from ES may be difficult because lymphomas may occasionally exhibit unexpected morphologic and immunophenotypic properties including LCA, CD3 and CD20 negativity and cytokeratin positivity. Additional analysis using CD79a, CD43, TdT, and PCR should be performed to avoid misdiagnosis. True ES is negative for lymphoid markers including CD79a, CD43, and TdT, as well as for IgH-R and Tγ-R.

Evidence that an Identical T Cell Clone in Skin and Peripheral Blood Lymphocytes is an Independent Prognostic Factor in Primary Cutaneous T Cell Lymphomas

The monoclonality of the T cell receptor gamma-chain gene was analyzed by polymerase chain reaction in skin and blood specimens of 85 patients with cutaneous T cell lymphomas including 67 mycosis fungoides, seven Sézary syndromes, and 11 CD30- nonepidermotropic cutaneous T cell lymphomas. A cutaneous T cell clone was detected in 69% of mycosis fungoides and 100% of Sézary syndromes. This frequency varied according to the clinical stage: 57% in early stages (Ia-IIa) to 96% in advanced stages (IIb-IV, Sézary syndrome). A peripheral blood T cell clone was detected in 42% of early stages and in 74% of late stages but was identical to the cutaneous one in 15% and in 63%, respectively. A significant association between initial clinical stage and T cell monoclonality was observed. In nonepidermotropic cutaneous T cell lymphomas, T cell monoclonality was detected in 55% of skin and 36% of blood samples. Univariate and multivariate analyses showed that, besides the initial clinical stage, an identical cutaneous and blood T cell clone was an independent prognostic factor for disease progression of mycosis fungoides/Sézary syndrome (hazard ratio 3.4, 95% confidence interval 1.4-9.9). Parallel polymerase chain reaction study of skin and blood specimens may therefore provide an initial prognostic marker that could help to monitor therapeutic strategies. A fully prospective study, with simultaneous therapeutic trials, needs to be done to confirm our findings and to include treatment variables in the statistical analysis.

Assignment of T cell receptor (TCR) alpha-chain gene (A), beta-chain gene (B), gamma-chain gene (G), and delta-chain gene (D) loci on swine chromosomes by in situ hybridization and radiation hybrid mapping

Using the cDNA sequence of porcine T-cell receptor (TCR) α-, β-, γ-, and δ-chain genes, we screened a porcine BAC library to isolate clones containing these genes. The isolated BAC clones were confirmed to carry these TCR genes by partial nucleotide sequencing. Among the clones obtained in the present screening, two clones carried both the TCR α-chain gene (TRA) and the TCR δ-chain gene (TRD) while one clone each carried only the sequence of either TRA or TRD. This observation demonstrated that TRA and TRD are localized in close proximity on a swine chromosome. Also two clones contained the sequence of the TCR β-chain gene (TRB), and two clones contained the sequence of TCR γ-chain gene (TRG). Fluorescence in situ hybridization using the above BAC clones as probes revealed that TRA and TRD, TRB, and TRG loci reside on swine chromosomes 7q15.3→q21, 18q11.3→q12, and 9q21→q22, respectively. The chromosome positions of TRA and TRB are consistent with those determined by somatic cell hybrid analysis (Rettenberger et al., 1996). In addition, RH mapping of these genes was performed using the INRA-University of Minnesota RH panel DNA. The result confirmed the position of TRA and TRB reported earlier (http://imprh.toulouse.inra.fr/), and further demonstrated that TRG was located 11 cR away from genetic marker SW989 toward the marker S0019.

Simple, reliable detection of T cell clones by PCR-LIS-SSCP analysis of TCRγ rearrangement

Clonal populations of T cells can be identified by polymerase chain reaction (PCR) amplification of the rearranged T cell receptor gamma (TCRG) chain gene. However, because of the limited combinatorial diversity of this locus it is necessary to separate the PCR product on the basis of sequence as well as size to distinguish clonal and polyclonal T cell populations. A simple method is described which achieves this by analysing the PCR product on a single-stranded conformation polymorphism (SSCP) gel. Sensitivity has been improved by denaturing the DNA using a low ionic strength (LIS) method rather than the more conventional alkali or formamide. Results from the PCR-LIS-SSCP method on a wide range of disorders and types of tissue samples show that clonality could be demonstrated in 40/44 cases.

The polymerase chain reaction in the demonstration of monoclonality in T cell lymphomas.

To evaluate polymerase chain reaction (PCR) amplification of T cell receptor (TCR) beta and gamma chain genes as a means of demonstrating monoclonality in T cell lymphomas using histological samples; to compare the performance of PCR with Southern blot analysis. TCR-beta, TCR-gamma and immunoglobulin heavy chain (IGH) genes were analysed using PCR in 55 cases of T cell lymphoma (28 frozen tissue and 27 paraffin wax embedded samples), diagnosed using morphological and immunohistochemical criteria. The 28 frozen samples were subjected to Southern blot analysis using TCR-beta, TCR-gamma and IGH gene probes. Twenty five B cell lymphomas and 21 non-neoplastic lymphoid tissue samples were used as controls. Using TCR-beta PCR, monoclonality was detected in 24 (44%) of 55 T cell lymphomas compared with 43 (78%) of 55 using TCR-gamma PCR and in 82% with both techniques. Five (9%) of 55 T cell lymphomas were IGH PCR positive. None of the non-neoplastic lymphoid control samples were PCR positive. All B cell lymphomas showed a polyclonal pattern with TCR-beta PCR while a single B cell lymphoma was positive using TCR-gamma primers. With TCR-beta PCR, a monoclonal result was seen in 12 (43%) of 28 frozen samples of T cell lymphoma, compared with 23 (82%) of 28 using Southern blot analysis. With TCR-gamma PCR, 19 (68%) of 28 frozen tissue samples were positive, compared with 26 (93%) of 28 using Southern blot analysis. A single case showed IGH rearrangement by Southern blot analysis. TCR-gamma PCR should be the method of choice for analysis of clonality in paraffin wax embedded sections of lymphoproliferative lesions, as TCR-beta PCR has a high false negative rate. Southern blot analysis remains the most successful technique when sufficient fresh tissue samples and resources are available.

Use of polymerase chain reaction in the detection of clones in lymphoproliferative diseases of the skin.

Early-stage mycosis fungoides shows similar clinical symptoms and histological and immunophenotypical features to several benign lymphoproliferative skin disorders. We analyzed T cell receptor gamma gene rearrangement by polymerase chain reaction in the search for monoclonal lymphoid subpopulations in skin infiltrates. Totally, 283 skin biopsies (paraffin-embedded and frozen material) from patients with different malignant and reactive skin diseases were investigated. Using primers for the T cell receptor gamma chain gene, monoclonality was detected in 59 out of 66 (89%) cases of pleomorphic cutaneous lymphoma, in 60 out of 78 (77%) patients with mycosis fungoides, in 11 out of 22 (50%) cases of parapsoriasis en plaques, in five out of 35 (14%) cases of pseudolymphoma, in six out of 15 (40%) patients with lymphomatoid papulosis, and in none out of 64 patients with inflammatory skin diseases. The results show that clonal T cell population can be detected in the majority of patients with cutaneous T cell lymphoma, but the findings have to be correlated with the histological and morphological features.

Defective V‐to‐J recombination of T cell receptor γ chain genes in scid mice

The status of T cell receptor gamma chain genes (TcR gamma) in 11 spontaneous T cell lymphomas from mice with severe combined immune deficiency (scid) was analyzed. We found that as a result of large abnormal deletions accompanying attempted site-specific V-to-J recombinations, 36 of 47 rearranged TcR gamma genes lacked the variable (V) and/or joining (J) region gene segment involved in this attempted recombination. No such deletions were found in T cell lymphomas from normal mice. We interpret our data as indicating a defective V-to-J recombination in scid lymphocytes consistent with our earlier observation of faulty D-to-J recombination in transformed scid lymphocytes (Schuler et al., Cell 1986. 46: 963). The present results further support the hypothesis that the scid mutation affects a component of the VDJ-recombinase system used in common by B and T cells to assemble antigen receptor genes.

In Vitro Immune-Receptor Gene Rearrangemets in Clonal Thymic Lymphomas Induced by Abelson Murine Leukemia Virus

The Abelson and Moloney murine leukemia virus complex (A-MuLV/M-MuLV) induces rapidly growing thymic lymphomas following direct injection into the thymus of newborn BALB/c and C57BL/6 mice. Southern blot analysis with a v-abl specific probe not only demonstrated that primary tumors are clonal, but also that the pattern of A-MuLV provirus integration is quite stable in primary tumor cells, as well as in their derived cell lines and clones. Most of the cell samples were able to rearrange the immunoglobulin heavy chain genes in culture, whereas in two cases the T cell receptor gamma chain genes also underwent rearrangement. Since the recombination mechanism is operative only in very immature lymphoid cells, these data provide indirect evidence for the lack of differentiation of A-MuLV cell targets in the thymus.

T cell receptor gamma and delta rearrangements in hematologic malignancies. Relationship to lymphoid differentiation.

We have studied recombinatorial events of the T cell receptor delta and gamma chain genes in hematopoietic malignancies and related these to normal stages of lymphoid differentiation. T cell receptor delta gene recombinatorial events were found in 91% of acute T cell lymphoblastic leukemia, 68% of non-T, non-B lymphoid precursor acute lymphoblastic leukemia (ALL) and 80% of mixed lineage acute leukemias. Mature B-lineage leukemias and acute nonlymphocytic leukemias retained the T-cell receptor delta gene in the germline configuration. The incidence of T cell receptor gamma and delta was particularly high in CD10+CD19+ non-T, non-B lymphoid precursor ALL. In lymphoid precursor ALL, T cell receptor delta was frequently rearranged while T cell receptor gamma was in the germline configuration. This suggests that TCR delta rearrangements may precede TCR gamma rearrangements in lymphoid ontogeny. In T-ALL, only concordant T cell receptor delta and gamma rearrangements were observed. Several distinct rearrangements were defined using a panel of restriction enzymes. Most of the rearrangements observed in T-ALL represented joining events of J delta 1 to upstream regions. In contrast, the majority of rearrangements in lymphoid precursor ALL most likely represented D-D or V-D rearrangements, which have been found to be early recombinatorial events of the TCR delta locus. We next analyzed TCR delta rearrangements in five CD3+TCR gamma/delta+ ALL and cell lines. One T-ALL, which demonstrated a different staining pattern with monoclonal antibodies against the products of the TCR gamma/delta genes than the PEER cell line, rearranges J delta 1 to a currently unidentified variable region.

Multiphenotypic Lymphoma with Rearrangements of the T Cell Receptor Beta Chain and Gamma Chain Genes

A case of chemotherapy-resistant non-Hodgkin's lymphoma simultaneously expressing T cell (CD7)-, B cell (CD19)- and myeloid (CD13, CD33)-associated surface antigens is presented. Cytochemical analysis revealed that the lymphoma cells were positive for terminal deoxynucleotidyl transferase, but negative for myeloperoxidase and esterase. Rearrangements of both the T cell receptor beta chain and gamma chain genes were observed, but the immunoglobulin genes showed a germ line configuration. The rearrangement was not detected within the breakpoint cluster region on chromosome 22. These findings are considered to represent aberrant expressions of the B cell- and myeloid-associated antigens in early-stage T cell lineage lymphoma cells.