Repertoire of the human T cell gamma genes: high frequency of nonfunctional transcripts in thymus and mature T cells

Evolution and function of the TCR Vgamma9 chain repertoire: It's good to be public

Lymphocytes expressing a T cell receptor (TCR) composed of Vgamma9 and Vdelta2 chains represent a minor fraction of human thymocytes. Extrathymic selection throughout post-natal life causes the proportion of cells with a Vgamma9-JP rearrangement to increase and elevates the capacity for responding to non-peptidic phosphoantigens. Extrathymic selection is so powerful that phosphoantigen-reactive cells comprise about 1 in 40 circulating memory T cells in healthy adults and the subset expands rapidly upon infection or in response to malignancy. Skewing of the gamma delta TCR repertoire is accompanied by selection for public gamma chain sequences such that many unrelated individuals overlap extensive in their circulating repertoire. This type of selection implies the presence of a monomorphic antigen-presenting molecule that is an object of current research but remains incompletely defined. While selection on a monomorphic presenting molecule may seem unusual, similar mechanisms shape the alpha beta T cell repertoire including the extreme examples of NKT or mucosal-associated invariant T cells (MAIT) and the less dramatic amplification of public Vbeta chain rearrangements driven by individual MHC molecules and associated with resistance to viral pathogens. Selecting and amplifying public T cell receptors whether alpha beta or gamma delta, are important steps in developing an anticipatory TCR repertoire. Cell clones expressing public TCR can accelerate the kinetics of response to pathogens and impact host survival.

Phenotype and TCR-gamma gene rearrangements in a Malaysian cohort of T-cell leukaemia/lymphoma cases

T cells undergo a series of complex phenotypic changes before achieving maturation. Discrete stages of T-cell differentiation are simplified to four stages (pro-, pre-, cortical and mature-T cell) and used in the classification of T-cell leukaemia. HLA-DR has been reported to be expressed in immature T-cell acute lymphoblastic leukemia (ALL) and also confer a poorer treatment outcome. Simultaneously, the genotype goes through distinct pattern changes due to rearrangement of T-cell receptor (TCR) genes. TCR gene rearrangement is important in the diagnosis of clonality and used as markers to detect minimal residual disease in lymphoproliferative disorders. We identified a subset within Pro-T and Pre-T cell cases distinguished by the expression of HLA-DR. These subgroups appeared to be more immature as rearrangement of the TCR-gamma gene was either at germline or involved only the first constant region (C1) unlike a more rearranged pattern in the HLA-DR-subgroups. We also observed a higher incidence of mediastinal mass (67%) in the HLA-DR-subgroup in the Pre-T stage. These characteristics may be useful as markers to further refine staging of T-cell ALL and determine prognosis.

Early TCR-beta and TCR-gamma PCR detection of T-cell clonality indicates minimal tumor disease in lymph nodes of cutaneous T-cell lymphoma: diagnostic and prognostic implications

The lymph nodes are generally the first extracutaneous manifestation in patients with cutaneous T-cell lymphoma (CTCL); however, their early involvement is difficult to assess. The aim of our study was to define the diagnostic and prognostic value of T-cell clonality analysis for a more precise assessment of lymph node involvement in CTCL. T-cell clonality was determined by 2 independent polymerase chain reaction (PCR) assays, namely a recently developed T-cell receptor-beta (TCR-beta) PCR technique as well as an established TCR-gamma PCR. T-cell clonality was found in 22 of 22 lymph nodes with histologically detectable CTCL involvement as well as in 7 of 14 histologically noninvolved dermatopathic lymph nodes. The clonal T-cell populations in the lymph nodes were in all cases identical to those detected in the corresponding skin lesions, identifying them as the tumor cell population. T-cell clonality was not found in any of the 12 dermatopathic lymph nodes from 12 patients with inflammatory skin diseases. Clonal T-cell detection in 7 of 14 dermatopathic lymph nodes of patients with CTCL was associated with limited survival (74 months; confidence interval [CI], 66-82 months) as in patients with histologically confirmed lymph node involvement (41 months; CI, 35-47 months), whereas all patients without T-cell clonality in the lymph nodes (7 patients) were alive at the last follow-up. Thus, T-cell clonality analysis is an important adjunct in differentiating benign dermatopathic lymphadenitis from early CTCL involvement.

High detection rate of T-cell receptor beta chain rearrangements in T-cell lymphoproliferations by family specific polymerase chain reaction in combination with the GeneScan technique and DNA sequencing

The distinction between benign polyclonal and malignant monoclonal lymphoid disorders by morphology or immunophenotyping is frequently difficult. Therefore, the demonstration of clonal B-cell or T-cell populations by detecting identically rearranged immunoglobulin (Ig) or T-cell receptor (TCR) genes is often used to solve this diagnostic problem. Whereas the detection of rearranged Ig genes is well established, TCR gamma (γ) and beta (β) gene rearrangements often escape detection with the currently available polymerase chain reaction (PCR) assays. To establish a sensitive, specific, and rapid method for the detection of rearranged TCR-β genes, we developed a new PCR approach with family-specific Jβ primers and analyzed the resulting PCR products by high-resolution GeneScan technique. The superior efficiency of this new method was demonstrated by investigating 132 DNA samples extracted from lymph node and skin biopsy specimens (mostly formalin fixed) and blood samples of 62 patients who had a variety of T-cell lymphomas and leukemias. In all but 1 of the tumor samples (98.4%) a clonal amplificate was detectable after TCR-β PCR and the same clonal T-cell population was also found in 15 of 18 (83%) of the regional lymph nodes and in 7 of 11 (64%) of the peripheral blood samples. Direct comparison of these results with those obtained currently by the most widely applied TCR-γ PCR revealed an approximate 20% lower detection rate in the same set of samples than with the TCR-β PCR method. These results indicate that the new TCR-β PCR is most suitable for a rapid and reliable detection of clonal T-cell populations.

High detection rate of T-cell receptor beta chain rearrangements in T-cell lymphoproliferations by family specific polymerase chain reaction in combination with the GeneScan technique and DNA sequencing

The distinction between benign polyclonal and malignant monoclonal lymphoid disorders by morphology or immunophenotyping is frequently difficult. Therefore, the demonstration of clonal B-cell or T-cell populations by detecting identically rearranged immunoglobulin (Ig) or T-cell receptor (TCR) genes is often used to solve this diagnostic problem. Whereas the detection of rearranged Ig genes is well established, TCR gamma (γ) and beta (β) gene rearrangements often escape detection with the currently available polymerase chain reaction (PCR) assays. To establish a sensitive, specific, and rapid method for the detection of rearranged TCR-β genes, we developed a new PCR approach with family-specific Jβ primers and analyzed the resulting PCR products by high-resolution GeneScan technique. The superior efficiency of this new method was demonstrated by investigating 132 DNA samples extracted from lymph node and skin biopsy specimens (mostly formalin fixed) and blood samples of 62 patients who had a variety of T-cell lymphomas and leukemias. In all but 1 of the tumor samples (98.4%) a clonal amplificate was detectable after TCR-β PCR and the same clonal T-cell population was also found in 15 of 18 (83%) of the regional lymph nodes and in 7 of 11 (64%) of the peripheral blood samples. Direct comparison of these results with those obtained currently by the most widely applied TCR-γ PCR revealed an approximate 20% lower detection rate in the same set of samples than with the TCR-β PCR method. These results indicate that the new TCR-β PCR is most suitable for a rapid and reliable detection of clonal T-cell populations.

Conformational and biochemical differences in the TCR.CD3 complex of CD8(+) versus CD4(+) mature lymphocytes revealed in the absence of CD3gamma

Mature CD4(+) and CD8(+) T lymphocytes are believed to build and express essentially identical surface alphabeta T-cell receptor-CD3 (TCR.CD3) complexes. However, TCR.CD3 expression has been shown to be more impaired in CD8(+) cells than in CD4(+) cells when CD3gamma is absent in humans or mice. We have addressed this paradox by performing a detailed phenotypical and biochemical analysis of the TCR.CD3 complex in human CD3gamma-deficient CD8(+) and CD4(+) T cells. The results indicated that the membrane TCR.CD3 complex of CD8(+) T lymphocytes was conformationally different from that of CD4(+) lymphocytes in the absence of CD3gamma. In addition, CD8(+), but not CD4(+), CD3gamma-deficient T lymphocytes were shown to contain abnormally glycosylated TCRbeta proteins, together with a smaller, abnormal TCR chain (probably incompletely processed TCRalpha). These results suggest the existence of hitherto unrecognized biochemical differences between mature CD4(+) and CD8(+) T lymphocytes in the intracellular control of alphabetaTCR. CD3 assembly, maturation, or transport that are revealed when CD3gamma is absent. Such lineage-specific differences may be important in receptor-coreceptor interactions during antigen recognition.

Clonal T-cell receptor gamma-chain gene rearrangement by PCR-based GeneScan analysis in advanced cutaneous T-cell lymphoma: a critical evaluation

Detection of clonal T-cell receptor gamma (TCRgamma)-chain gene rearrangement is a promising approach to distinguish between cutaneous T-cell lymphomas (CTCLs) and reactive T-cell infiltrates. Despite the improved sensitivity by using the polymerase chain reaction (PCR) rather than Southern blot analysis, monoclonality could be demonstrated in only 53-90 per cent of CTCL biopsies in recent studies. In the present study, formalin-fixed, paraffin-embedded specimens of 21 selected patients with clear-cut advanced-stage CTCL were analysed using a semi-nested TCRgamma PCR with newly developed consensus primer pairs. Detection of PCR products was done by GeneScan analysis (GSA); this technique is advantageous due to its sensitivity and accuracy in the detection and size determination of PCR products and it is easier to interpret than direct read-outs from TGGE or DGGE gels. In serial dilution experiments, TCRgamma-PCR-GSA allowed the detection of clonal, rearranged T-cells with a high in vitro sensitivity against a polyclonal background (1-6 per cent). Despite the selection of clear-cut, advanced-stage CTCL cases, however, dominant clonal TCRgamma-chain gene rearrangement was found in only 16 of the 21 patients analysed, indicating an overall clinical sensitivity of 76 per cent. Specificity was evaluated using biopsy specimens from 21 control patients suffering from long-standing psoriasis (n=13) and eczema (n=8). Surprisingly, GeneScan profiles showing apparently single dominant peaks were detected in 14 per cent of these skin lesions, but these profiles turned out to be pseudo-monoclonal by repeated determinations. In conclusion, TCRgamma-PCR-GSA does not suffice reliably to exclude malignancy, due to its limited clinical sensitivity, but with precautions taken to detect pseudo-monoclonality and to secure specificity, TCRgamma-PCR-GSA is a valuable instrument in the diagnosis of CTCL.

Non-Hodgkin's lymphomas in Mexico. A clinicopathological and molecular analysis

It is now well established that the clinical and histopathological characteristics of non-Hodgkin's lymphomas may vary significantly throughout the world. However, only a few reports have been published in Latin American countries. In this work, the clinical and pathologic findings of 264 patients with non-Hodgkin's lymphomas in Mexico City were analyzed. Diffuse large (14%) and diffuse mixed cell types (20%) predominated among nodal lymphomas. Within the group of patients with high grade malignancies, immunoblastic sarcomas were the most common (40/48). It is important to mention that follicular lymphomas were sporadic (4.5%). Among extranodal lymphomas the most commonly involved site was the gastrointestinal tract (11.3%), followed by the midline (6%). Molecular analysis of 65 cases with immunoglobulin and T-cell receptor gene probes showed that most lymphomas were of B-cell lineage (66%). The remaining group was composed of T-cell (25%) and bigenotypic malignancies (9%). All attempts to establish a correlation between the clinical stage and histopathological types with the genetic findings were not successful. However, pre-B and bigenotypic lymphomas were observed mainly in patients over 60 years of age. This study highlights some relevant characteristics of non-Hodgkin's lymphomas in Mexico.

Molecular analysis of childhood acute lymphoblastic leukemia in Israel

Ninety-two Israeli children with acute lymphoblastic leukemia (ALL) (67 B-lineage and 25 T-lineage) were analyzed for the immunological antigen receptor gene configuration. Thirty-nine of the patients (27 B-lineage and 12 T-lineage) relapsed. The incidence of the identified rearrangements within the immunoglobulin heavy chain (IgH) and T-cell receptor (TCR)beta, gamma and delta genes, at diagnosis, was in accordance with previous studies from other countries. Furthermore, the clinical relevance of bi/oligoclonal status, at diagnosis, and clonal selection was determined in this long-term follow-up study (median 112 months). A similar relapse rate was observed among the B-lineage patients with bi/oligoclonal and monoclonal patterns indicated by IgH gene rearrangement. Based on our results, we suggest that bi/oligoclonality has no prognostic significance (P=0.8533). Clonal variations between diagnosis and subsequent relapses were detected in 60% (12/20) of the patients; 64% (7/11) B-lineage and 55% (5/9) T-lineage. Clonal selection significantly correlated with shorter duration of remission and earlier recurrence (P=0.0025).

Differences in T-cell-receptor gene rearrangement and transcription in nasal lymphomas of natural killer and T-cell types: implications on cellular origin

Although nasal lymphomas showing midfacial destructive lesions had been classified as T-cell lymphomas, their exact cellular origin is still unclear. Although they usually express a restricted number of T-cell-related antigens, namely, CD2, CD43, and CD45RO, other pan-T or subset-T-lineage antigens, such as CD3 (membrane), CD5, CD4, CD8, and CD7, are frequently absent. Conversely, they often express a natural killer (NK) cell-associated antigen, CD56, but lack other mature NK markets. To study their cellular origin further, the authors analyzed T-cell receptor (TCR) gene transcription in three cases of nasal lymphomas and correlated the findings with the phenotype and gene rearrangement data. Two cases of nasal lymphomas with CD2+CD3(Leu4)-CD19-CD56+ phenotype were shown to express truncated 1.0-kb Tbeta and multiple unrearranged Tdelta transcripts with germline TCR beta, gamma, delta, and immunoglobulin heavy-chain joining region (JH) genes, consistent with NK cell lineage. In contrast, one case of nasal lymphoma with CD2+CD3(Leu4)+CD8+CD19-CD56+ phenotype expressed full-length Talpha, Tbeta, and Tgamma transcripts rearranged TCR beta, gamma, and deleted TCR delta genes, indicating T-lineage, These results support the view that nasal lymphomas can separated into NK-cell and T-cell neoplasms, based on differences genotypic characteristics. The possibility of these tumors being derived from a putative common precursor cell merits further investigation.

The human T-cell receptor gamma variable pseudogene V10 is a distinctive marker of human speciation

The V10 variable gene of the human T-cell receptor gamma locus (TCRG-V10), the only member of the subgroup III, has a structural defect which inhibits the splicing of the leader intron. We show that there is a single point mutation in the V10 leader donor splice site responsible for this situation and that this mutation is found in the different populations tested, indicating that V10 corresponds to a pseudogene in humans. We restored the splice site by mutagenesis and obtained correct splicing in vitro. Analysis of the V10 germline gene in different primates reveals functional splice sites in the closest human apes, the chimpanzee and the gorilla. The splice competence of TCRG-V10 in higher primates was addressed in peripheral blood lymphocytes from chimpanzee by specific cDNA amplification, and correct splicing of the TCRG-V10 leader intron was found as well as a majority of in frame rearrangements involving only the TCRG-J1 or J2 segments. These results suggest that V10(+)gamma /delta T cells may represent an important subset in the non-human higher primates, contrary to the situation observed in the human.

Human T-cell receptor variable gene segment families

Multiple DNA and protein sequence alignments have been constructed for the human T-cell receptor alpha/delta, beta, and gamma (TCRA/D, B, and G) variable (V) gene segments. The traditional classification into subfamilies was confirmed using a much larger pool of sequences. For each sequence, a name was derived which complies with the standard nomenclature. The traditional numbering of V gene segments in the order of their discovery was continued and changed when in conflict with names of other segments. By discriminating between alleles at the same locus versus genes from different loci, we were able to reduce the number of more than 150 different TCRBV sequences in the database to a repertoire of only 47 functional TCRBV gene segments. An extension of this analysis to the over 100 TCRAV sequences results in a predicted repertoire of 42 functional TCRAV gene segments. Our alignment revealed two residues that distinguish between the highly homologous V delta and V alpha, one at a site that in VH contacts the constant region, the other at the interface between immunoglobulin VH and VL. This site may be responsible for restricted pairing between certain V delta and V gamma chains. On the other hand, V beta and V gamma appear to be related by the fact that their CDR2 length is increased by four residues as compared with that of V alpha/delta peptides.

Gene rearrangements and chromosomal translocations in T cell lymphoma--diagnostic applications and their limits

The diversity of the T cell receptor (TCR) repertoire is established for individual T lymphocytes by developmentally regulated gene rearrangements and shaped by predominantly intrathymic selection procedures. TCR gene probes in Southern blot experiments and TCR primers for the polymerase chain reaction (PCR) help to distinguish polyclonal from abnormal clonal T cell proliferations and to monitor clonal disease after treatment. Rearrangement studies can identify the lineage and developmental stage of a lymphocyte clone. Cross-lineage rearrangements, false positive or negative results are rarely misleading when morphology and immunophenotypical findings are considered. Rearrangement studies, however, have not contributed significantly to the comprehension of lymphomagenesis. Analyses of characteristic chromosomal translocations in T cell leukaemias and lymphomas may provide further insight into the mechanisms of malignant transformation. Transcription factors are often involved and sometimes abnormally transcribed, which may alter the physiological intracellular signalling in T cells. Interphase cytogenetic analysis by chromosomal fluorescence in situ hybridization (FISH) has become a new tool in the search for transformed T cells carrying specific translocations. Archival biopsy material is now accessible for PCR rearrangement studies and FISH cytogenetics. This adds another dimension to the diagnosis, disease monitoring and biological understanding of malignant T cell lymphomas and leukaemias.

T cell receptor gamma gene polymorphisms and class II human lymphocyte antigen genotypes in patients with celiac disease from the west of Ireland

Although celiac disease has one of the strongest human lymphocyte antigen (HLA) class II associations of any human illness, it is clear that at least one gene that is not linked to the HLA region also is required for its pathogenesis. The occurrence of large numbers of gamma delta T cells in the bowel mucosa of patients and the recent description of T cell receptor (TCR) gamma chain polymorphic variants identified by restriction fragment length polymorphism analysis led the authors to examine TCR gamma genotypes in relation to HLA-DR, DQ genotypes in 89 patients with celiac disease and 55 control subjects from the West of Ireland. The overall frequency of TCR gamma genotypes in patients and control subjects was comparable. However, most of the patients had 1 of 3 HLA-DR3 genotypes (DR3/15, 3/7, or 3/3), and there was a significant alteration of the expected frequency of TCR gamma genotypes among patients with these three genotypes. The major differences were an increased association of HLA-DR3 homozygosity, with TCR gamma genotypes having a 16.0 kb fragment and an increased frequency of DR3/7 heterozygosity and decreased frequency of DR3/15 heterozygosity, respectively, in association with the TCR gamma 13.0/11.3 kb genotype. Based on their results, there is the possibility that an interaction between the products of two polymorphic and unlinked gene regions contributes to the pathogenesis of celiac disease.

Analysis of gamma delta V region usage in normal and diseased human intestinal biopsies and peripheral blood by polymerase chain reaction (PCR) and flow cytometry

The intestinal population of gamma delta T cell receptor (TCR)-bearing cells was characterized with regard to V delta and V gamma subtype expression. For this purpose, we utilized V gene-specific PCR of mRNA prepared from intestinal biopsies. Predominant expression of the V delta 1 subtype was demonstrated in the small intestine of patients with coeliac disease and in the inflamed colon of patients with inflammatory bowel diseases (IBD: ulcerative colitis and Crohn's disease) as well as in colon biopsies taken from macroscopically normal areas of colon. Although intestinal gamma delta T cells preferentially expressed V delta 1, other V delta transcripts could be detected, of which V delta 2 and V delta 5 were commonly expressed. Analysis of biopsies from mesenteric lymph nodes demonstrated a V delta repertoire similar to the mucosa. In peripheral blood on the other hand, high expression of both V delta 2 and V delta 1 was found. The predominant expression of V delta 1 transcripts in the intestinal mucosa of IBD patients correlated well with protein cell surface expression as analysed by flow cytometry using V delta 1- and V delta 2-specific antibodies. Selective expansion of gamma delta T cells could not be demonstrated within the inflamed mucosa as shown by mRNA analysis and flow cytometry. Instead, IBD patients demonstrated a decreased proportion of TCR gamma delta-carrying T cells in the inflamed mucosa compared with macroscopically normal area of colon. On the other hand, a significantly increased percentage of T cells bearing the gamma delta TCR was found in peripheral blood of patients with Crohn's disease compared with healthy individuals, indicating that local mucosal inflammation may influence the circulating gamma delta T cell population.

Identification of a T cell-specific transcriptional enhancer 3' of the human T cell receptor gamma locus

Positive and negative transcriptional regulatory mechanisms are thought to play a major role in the expression of T cell antigen receptor (TCR) genes. Since the alpha beta and gamma delta T cell receptor heterodimers are expressed in a mutually exclusive fashion and since TCR genes are sequentially activated during T cell ontogeny, transcriptional activation and repression must at least in part determine T lineage-specific and developmental-specific expression of these genes. We have identified a transcriptional enhancer located 6.5 kb downstream from the human T cell receptor gamma (TRG) locus. The nucleotide sequence of the enhancer core element shows strong sequence homology to the recently identified murine C gamma 1 enhancer. The enhancer demonstrates T cell-specific activity, but not gamma delta sublineage-specificity in combination with either a heterologous or gene-specific promoter. Thus, additional regulatory elements may be required to repress the expression of rearranged TRG genes in non-gamma delta T cells.

T cell receptor gamma cDNA in human fetal liver and thymus: variable regions of gamma chains are restricted to V gamma I or V9, due to the absence of splicing of the V10 and V11 leader intron

Although complete in-frame transcripts of the human T cell receptor gamma V10 and V11 genes have been described, the corresponding gamma chains have never been found in gamma delta T cell receptors. In this study, we show that the leader intron of all V10 and V11 cDNA isolated from fetal thymus, fetal liver and adult peripheral blood lymphocytes are unspliced. We demonstrate that, due to the absence of splicing, V10 and V11 are pseudogenes and cannot be expressed in gamma chains. They are the first pseudogenes of this type described in a rearranging T cell receptor/immunoglobulin locus. Therefore the gamma repertoire at the protein level is limited to subgroup V gamma I and to V9. By analysis of the gamma polymerase chain reaction products from total cDNA, we find that the gamma locus is active in early ontogeny (8 weeks), as shown by the presence of rearranged V9 and V10 gene transcripts in the liver. At 13 weeks, the V gamma I genes as well as V9 and V10 have undergone productive rearrangements in the liver, and in the thymus. Most rearrangements, if not all, involve the T cell receptor gamma C1 region (JP1, JP, J1 segments) in both tissues, confirming the accessibility of the C1 region in early stages of development.

T cell receptor polymorphisms in Caucasians and Polynesians

The purpose of this study was to find genetic polymorphisms that might be useful in studies of Polynesian-Caucasian racial admixture and Polynesian disease susceptibility. The allele frequencies of six T cell receptor locus RFLP were measured in 73 Caucasians and two Polynesian ethnic groups comprising 86 Maoris and 95 Samoans. The RFLP studied were (locus/enzyme/probe): C alpha/Taq1/Y14, V alpha/Taq1/Y14, C beta/BglII/Y35, C gamma/Pvu II/HGP02, V beta 7/BamHI/V beta 7.4 and V beta 8/Bam HI/V beta 8.1. Racial differences in allele frequency were present with all six RFLP (P < 0.001). The allele frequencies of the V alpha/Taq1/Y14 and the V beta 7/BamHI/7.4 RFLP were similar in the two Polynesian groups, both of which differed from the Caucasians. The 1.4 kb allele of the V alpha/Taq1/Y14 RFLP and the 8.0 kb allele of the V beta 7/BamHI/7.4 RFLP were present in low frequency in both Polynesian groups compared to the Caucasian group, consistent with a gene flow effect. These alleles may be useful in studies of Caucasian-Polynesian racial admixture.

T-cell receptor alpha, delta, and gamma chain genes in insulin-dependent diabetes mellitus

We have studied the genotypic, haplotypic, and allelic distribution of germline Restriction Fragment Length Polymorphism (RFLP) of T-cell receptor (Tcr) alpha, gamma, and delta loci in 75 insulin-dependent diabetes mellitus (IDDM) patients and 84 healthy blood donors as control population. The restriction endonuclease PvuII produces three allelic fragments of Tcr C gamma (TcrCG) gene segment of 16, 13, and 11.3 Kb respectively. Our observations revealed that PvuII/TcrCG RFLP allelic distributions were not significantly different in the IDDM and the control group. However, 85% of IDDM patients carried HLA DR3 and/or DR4 haplotypes, and when comparing these patients with a second group of HLA DR3+ and/or DR4+ healthy individuals, the 11.3 Kb/PvuII fragment of TcrCG gene was found to be associated with IDDM patients (chi 2 = 11.4, P = 0.003). 54.9% of IDDM patients carried at least one 11.3 Kb allele vs. 21% in controls (chi 2 = 10.77, P = 0.004). No significant association was found between RFLP in Tcr, C alpha, C delta, V gamma 9 loci and IDDM.

Isolation and characterization of gamma delta T lymphocyte cell lines from Sinclair swine peripheral blood

Sinclair miniature swine represent a breed of miniature swine which display a significant incidence of inheritable melanoma which undergo a developmentally regulated spontaneous regression. In an attempt to characterize the host cellular immune response to the melanoma, lymphocyte cell lines have been generated from peripheral blood and designated as peripheral blood lymphocyte cell lines (PBLCLs). The cell lines were expanded in vitro without the addition of exogenous mediators, cloned by limiting dilution, and characterized by flow microfluorimetry, Western, and Northern blot analysis. The cell lines were shown to be CD2-, CD4-, CD8-, and slg-, a phenotype consistent with a null cell population described in swine. The null cell population in swine has been reported to consist of a subpopulation of cells which express the gamma delta T cell receptor (TCR) heterodimer, swine gamma delta T lymphocytes. The PBLCLs were further analyzed by flow microfluorimetry and observed to express the IL-2R, swine MHC Class II antigens, and the endothelial lymphocyte adhesion marker (CD44), which can function as a homing receptor for the skin. In addition, the PBLCLs were observed to express the antigen which is recognized by mAb 86D, an antibody that has been reported to recognize an external epitope on a subset of gamma delta TCR bearing swine T lymphocytes. Western blot analysis of Triton X-114 phase fractions of a PBLCL revealed a protein recognized by the W6 antibody, an antibody which recognizes a conserved region of the C delta chain. Furthermore, Southern and Northern blot analysis indicated that the PBLCL have rearranged the TCR gamma chain gene and express mRNA from the TCR gamma and delta chain genes prior to and following treatment with ionomycin or Concanavalin A. Therefore, the data indicates that the PBLCLs represent swine gamma delta T lymphocyte cell lines which should enable us to enhance our understanding of the role of gamma delta T lymphocytes in the porcine immune system.

CD4+, CD45RA+, CD29- T-cell lymphocytic leukemia functioning as T suppressor inducer for B-cell immunoglobulin synthesis

We describe here a case of T-cell lymphocytic leukemia (T-CLL) which coexpressed CD4 and CD45RA cell-surface antigens and functioned as suppressor inducer cells. The patient, an 81 year-old man, had massive generalized lymphadenopathy. His hemoglobin was 9.4g/dl, the platelet count 94,000, and the WBC was 895,000/microliters with 98% abnormal lymphoid cells. He had massive hepatosplenomegaly. Serum LDH was elevated to 3,990 u/l. The T-CLL cells coexpressed antigens detected by MAbs CD2, CD3, CD4, CD5, Ti(TcR alpha/beta; WT31) CD45 and CD45RA, but did not express any other antigens including CD1, CD8, CD29, and TCR gamma/delta, Ti gamma A and TQ-1. The cell-surface phenotypes of the cultured cells established by utilizing recombinant interleukin 2 were basically the same as those of the uncultured peripheral blood lymphoid cells. Both the peripheral blood and cultured cells clearly showed gene rearrangement for T cell receptors, TcR beta and TcR gamma. No association with human T-cell leukemia virus-1 (HTLV-1) was found by means of electron microscopic studies or the application of MAbs to p19 and p24 of HTLV-1. No anti-HTLV-1 antibody was detected. By the means of two color fluorescence, it was clearly demonstrated that the leukemic cells possessing CD4 in the peripheral blood and cell cultures coexpressed CD45RA, but did not express either CD29 or TQ-1. In vitro immunoglobulin synthesis by normal T and B cells was remarkably reduced in the presence of CD8+ T and leukemic cells. This suggests suppressor inducer T cell activity for the leukemic cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Gamma delta T cell receptor repertoire in brain lesions of patients with multiple sclerosis

The identification of activated T cells in the brains of patients with multiple sclerosis (MS) suggests that these cells are critical in the pathogenesis of this disease. Recently we have used the PCR method to analyse rearrangements of V alpha and V beta genes of the T cell receptor (TCR) in samples of MS and control brains. The results of these studies showed that TCR V gene usage in MS brains may be restricted and in particular that V beta genes may be preferentially rearranged in certain HLA haplotypes associated with susceptibility to MS. In view of the recent evidence that T lymphocytes bearing the gamma delta chains may have autoreactive potential, we have assessed whether or not such TCR-bearing lymphocytes were also present in chronic MS lesions. TCR V gamma and V delta were analysed by the PCR method using a panel of V gamma and V delta primers paired with C gamma or C delta primers in 12 MS brains, as well as in brain samples of ten normal post-mortem cases and three neurological controls. TCR V gamma-C gamma and V delta-C delta rearrangements were confirmed using Southern blotting and hybridisation of the PCR products with specific C gamma and C delta probes. Only one to four rearranged TCR V gamma and V delta transcripts were detected in each of the 23 brain samples obtained from 12 MS patients, with the majority of gamma delta T cells expressing the V gamma 2 and V delta 2 chains. In marked contrast, V gamma and V delta transcripts could only be found in one of the ten non-neurological control brains analysed. To assess the clonality of V gamma 2 and V delta 2 T cell receptor chains in the brain samples of MS patients, we have sequenced the junctional regions of the TCR V gamma-N-J gamma-C gamma and V delta-N-D delta-N-J delta-C delta segments amplified from brain tissues, CSF and spleens of two MS patients and from the spleen of two control subjects. The sequence analysis obtained so far shows no compelling evidence of an MS specific expansion of one or more clones expressing particular types of gamma delta T cell receptors. In contrast, a clonal expansion of a different population of TCR gamma delta-bearing T cells was found in the spleen of both an MS patient and one of the control individuals.(ABSTRACT TRUNCATED AT 400 WORDS)

Divergent T cell receptor gamma repertoires in rheumatoid arthritis monozygotic twins

OBJECTIVE

To determine if the expressed T cell receptor (TCR) gamma repertoire is altered in rheumatoid arthritis (RA).

METHODS

Peripheral blood lymphocytes were collected from monozygotic twins who were either concordant or discordant for RA, or from a normal twin pair. TCR gamma-specific complementary DNA libraries were constructed using the anchored polymerase chain reaction. Gene usage was analyzed by plaque hybridization and sequencing.

RESULTS

The expressed TCR V gamma repertoires both in RA patients and normal subjects were extremely diverse. Monozygotic twins who were concordant for RA expressed very different frequencies of TCR V gamma genes.

CONCLUSION

RA does not lead to a specific clonal expansion or deletion of TCR V gamma genes in peripheral blood.

Regulation of the mature human T cell receptor gamma repertoire by biased V-J gene rearrangement

To delineate how gene rearrangement influences the expressed human gamma delta T cell repertoire, we generated T cell receptor gamma (TCR gamma) V domain-specific cDNA libraries from the peripheral lymphocytes of eight donors and sequenced a total of 232 TCR gamma gene transcripts. The libraries consisted of both in-frame and out-of-frame rearranged TCR gamma genes. The in-frame TCR gamma gene transcripts were used to determine the diversity of functional T cells, whereas the out-of-frame transcripts, primarily derived from alpha beta T cells, were used to assess the frequencies of TCR V gamma-J gamma rearrangements in progenitor T lymphocytes. The results showed that both sets of transcripts exhibited strikingly restricted V gamma-J gamma combinations. Only 11 of 40 potential V gamma-J gamma rearrangements were common ( > or = 3% of total). The pattern of gene usage in the functional and nonfunctional transcripts was similar and did not differ markedly among donors. The only exception was the predominance of V gamma 9-JP in potentially functional transcripts from seven of eight individuals. These results show that V gamma-J gamma rearrangement is nonrandom and suggest that the diversity of TCR gamma genes in the functional gamma delta T cell repertoire partly depends upon preferentially rearranged V gamma-J gamma gene combinations. However, the expansion of V gamma 9/V gamma 2 T cells in adult peripheral blood can only be explained by antigenic selection of relatively rare V gamma 9-JP recombinants.

Development of the non-palindromic adaptor polymerase chain reaction (NPA-PCR) for the amplification of alpha- and beta-chain T-cell receptor cDNAs

We have developed a highly efficient new method for the amplification of alpha- and beta-chain human T-cell receptor (TCR) cDNAs. This method is designated non-palindromic adaptor polymerase chain reaction (NPA-PCR). cDNA was synthesized from total RNA isolated from mononuclear leucocytes, using either an oligo (dT)15-NotI or a C alpha-NotI or a C beta-NotI primer and RNase H-negative reverse transcriptase. The double-stranded cDNA was ligated with the non-palindromic adaptors EcoRI-XmnI [d(ATTCGAACCCCTTCG)] and XmnI G strand [d(pCGAAGGGGTTCG)] (phosphorylated), which resulted in the addition of the EcoRI-XmnI site in both 5' and 3' ends. These two non-palindromic adaptors, EcoRI-XmnI and XmnI G strand, are complementary to each other and both are required for ligation. The EcoRI-XmnI adaptor was removed from the 3' end by treatment with NotI restriction nuclease, whereas it was retained at the 5' end. The non-palindromic adaptor EcoRI-XmnI was used as the 5' amplification primer. C alpha or C beta constant region primers were used as 3' amplification primers. The amplified cDNAs were cloned and the plasmids were used to transform DH5 alpha competent cells. Over 1000 white colonies per 0.1-0.25 micrograms of total RNA or per 10,000 to 50,000 human peripheral blood mononuclear cells were obtained after amplification of either the alpha- or the beta-chain TCR cDNAs. Between 40 and 62% of the colonies (range from five donors) were positive after screening with either a C alpha or a C beta probe, located 5' to the C alpha and C beta amplification primers. A total of 50 amplified alpha- or beta-chain cDNA positive clones from two normal donors were randomly chosen and sequenced, and the sequences obtained were typical of alpha beta TCR. Two new J alpha gene segments were identified. Approximately 30% of the alpha-chain positive clones have 5' untranslated region, and most of the remaining alpha- or beta-chain TCR clones started from the initiation codon or near the 5' end. NPA-PCR has several advantages over existing PCR methods for the amplification of cDNAs with unknown or variable 5' end, such as the T-cell antigen receptors and the immunoglobulins. Among these advantages is that only one 5' end extension primer is required. Because of the large number of TCR V alpha and V beta families, a large number of different 5' end primers are required for amplification of alpha beta TCR cDNAs by conventional PCR.

Pathogenic autoantibody-inducing gamma/delta T helper cells from patients with lupus nephritis express unusual T cell receptors

In previous work, we found that only 59 (15%) of 396 "autoreactive" T cell clones derived from five patients with lupus nephritis had the ability to selectively augment the production of pathogenic anti-DNA autoantibodies and the majority (49/59) of those autoimmune T helper (Th) clones were CD4+. Surprisingly, 7 of those Th clones were CD4-/CD8- and gamma/delta TCR+, capable of augmenting the production of pathogenic anti-DNA autoantibodies up to 125-fold. The gamma/delta Th clones responded in a MHC-nonrestricted manner to some endogenous autoantigen associated with heat shock proteins (HSP60) on the lupus B cells. The gamma/delta TCR genes expressed by 4 of these Th clones were amplified and sequenced here. Three of the 4 Th clones, each from a different lupus patient, expressed a gene from the V gamma 1 subgroup. Moreover, 2 of the Th clones expressed V delta 5, and the others V delta 1 or V delta 3. These TCRs are rarely expressed by peripheral blood gamma/delta T cells of normal adult humans. The predominant gamma/delta T cells in human peripheral blood express V gamma 2 (V gamma 9) and V delta 2 TCR genes, including HSP-responsive T cells. None of the lupus Th clones expressed this combination of TCR genes. In addition, some of these pathogenic autoantibody-inducing Th clones from the lupus patients had limited diversity and few N-nucleotide additions in their gamma/delta TCR junctional regions (CDR3), thus resembling fetal gamma/delta thymocytes early in ontogeny.

Evolution of Ig- and T-cell receptor gene configuration in a Ph1+ hybrid leukemia patient

In a longitudinal study of a 32-year-old male with Ph1+ hybrid leukemia we have followed the immunophenotype and configuration of Ig- and TCR genes during the course of different chemotherapy regimens directed first against the myeloid and later against the lymphoid components of the disease. We identified changes in all parameters, interpretable as an evolution of the malignant clone resulting in a leukemic switch towards a more lymphoid character. Thus, while the expression of the myeloid antigens CD13 and CD33 decreased, that of CD10 (CALLA) and CD20 (B1) increased. Moreover, while the configuration of the Ig heavy and light chain lambda genes remained constant during the whole period of treatment, that of the Ig light chain kappa gene and TCR beta gene displayed extensive rearrangements after initiation of ALL therapy. Since this patient represents a de novo acute leukemia as evaluated by location of the translocation-breakpoint on chromosome 22, our data clearly indicate that Ig- and TCR gene rearrangements might prove a valuable addition in monitoring Ph1+ hybrid leukemias, providing guidelines for optimizing chemotherapy.

Variable gene usage of T cell receptor gamma- and delta-chain transcripts expressed in synovia and peripheral blood of patients with rheumatoid arthritis

The synovial tissue and fluid of patients with rheumatoid arthritis (RA) contain activated T cells that probably have a central role in the disease process which leads to joint destruction. A subset of T cells, gamma delta T cells detected at the site of inflammation, may be important in the pathogenesis of the disease. This study investigated variable (V) gene usage of gamma delta T cell receptors (TcRs) expressed in synovia and peripheral blood of patients with RA by using the polymerase chain reaction (PCR) to amplify TcR gamma- and delta-chain transcripts. Most patients showed no restriction in V gamma gene usage since synovial mononuclear cells (SMC) expressed TcR gamma-chain transcripts which used the same set of V gamma genes as peripheral blood mononuclear cells (PBMC). In contrast, the majority of patients expressed a restricted SMC V delta-chain repertoire biased towards V delta 1, but V delta 2 mRNA transcripts were also detected, albeit at low levels in some patients. The TcR delta-chain repertoires of PBMC from healthy control subjects were also characterized. There was variation in the TcR delta-chain repertoires of PBMC from patients when compared with controls, particularly with respect to expression of V delta 4. V delta 4 mRNA transcripts were expressed in PBMC of only two of seven RA patients in contrast with eight of the nine controls (P = 0.03). These findings are compatible with reports that gamma delta T cells in the rheumatoid synovium are reactive to Mycobacterium tuberculosis and that response to M. tuberculosis is restricted to V gamma 9/V delta 2-bearing T cells, if a superantigen is involved in the pathogenesis of RA.

Differential regulation of gamma and delta T cell antigen receptor gene expression by phorbol esters and Ca2+ ionophores in the acute lymphocyte leukemia DND41 cell line

We have investigated the role of two signal transduction pathways on the regulation of the gamma and delta T cell antigen receptor (TcR) gene expression, in the acute lymphocytic leukemic cell line DND41. Protein kinase C (PKC) activation, and intracellular free Ca2+ mobilization, initiated by phorbol esters and calcium ionophores, respectively, not only acted independently but, more interestingly, their effects were antagonistic, suggesting a role for these signals during T cell differentiation. The Ca2+ ionophore, ionomycin, increased the levels of intracellular free Ca2+ and induced the expression of the gamma and delta chains of the T cell antigen receptor in a concentration-dependent manner. The phorbol ester 12-myristate 13-acetate down-regulated the basal gamma TcR expression with marginal effect on delta TcR mRNA, but diminished the induction of both gamma and delta TcR, initiated by the Ca2+ ionophore. These antagonistic effects of the two arms of the phospholipase C-mediated signal transduction pathways, i.e. PKC activation and increased intracellular free Ca2+, were specific to the regulation of the gamma and delta TcR, since the same signals exerted a synergistic effect on the mRNA levels of interleukin 2 receptor. These data confirm our hypothesis that the antagonistic regulation on the gamma and delta TcR gene expression by phorbol esters and calcium ionophores occurs in the same cell, and stresses the biological significance of PKC activation and intracellular free calcium mobilization during intrathymic differentiation and selection.

In vitro expansion of CD3/TCR- human thymocyte populations that selectively lack CD3 delta gene expression: a phenotypic and functional analysis

Highly purified CD1-3-4-8- human thymocytes were obtained by panning techniques combined with cell depletion with antibody-coated magnetic beads. Most of these cells expressed cytoplasmic CD3 antigen, as assessed by mAbs known to react with the CD3 epsilon chain. After culture with low doses of PMA (0.5 ng/ml) and subsequent addition (at 24 h) of recombinant interleukin 2 (rIL-2; 100 U/ml) cells underwent extensive proliferation (40-60-fold of the initial cell input after 2 wk). The majority of the proliferating cells were CD3-TCR-. The remaining cells (5-40%) were represented by CD3+ TCR gamma/delta+ (BB3- A13+) cells. Further removal of CD3+ TCR-gamma/delta+ cells resulted in highly purified CD3- populations that further proliferated in culture with no substantial phenotypic changes. When CD3+ thymocytes were cultured under the same experimental conditions, only CD3+ TCR-alpha/beta+ cells could be detected, thus indicating that PMA did not affect the surface expression of the CD3/TCR complex, but rather induced preferential growth of CD3- thymocytes. Surface marker analysis of cultured CD3- thymocytes showed that they were homogeneously CD7+, whereas low proportions of cells expressed CD2 and CD8 antigens. Among the natural killer (NK) cell markers, CD56 was highly expressed by all cells, whereas CD16, CD57, CD11b, NKH2, and GL183 were absent. Importantly, these cells were different from peripheral NK cells, as 80-95% of them expressed cytoplasmic CD3 antigen. Functional analysis revealed a strong cytolytic activity against both NK-sensitive (K562) and NK-resistant (M14, Daudi) human target cells. In a redirected killing assay against the Fc gamma R+ P815 cells, mAbs specific for triggering molecules including CD3, CD2, and CD16 failed to augment target cell lysis, while a strong cytolytic effect was induced by PHA. In addition, PHA alone or in combination with PMA induced tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) (but not IL-2) production by CD3- thymocytes. Cloning of fresh CD1-3-4-8-thymocytes in the presence of PMA and rIL-2 resulted in CD3-CD56+ clones that displayed a pattern of cytolytic activity and lymphokine production similar to that of the polyclonal populations. Northern blot analysis of transcripts coding for CD3/TCR molecules revealed the presence of CD3 zeta, epsilon, and gamma transcripts, while CD3 delta was undetectable. Mature transcripts for both gamma and delta TCR chains could be detected, whereas no TCR-alpha mRNA and only a truncated (1.0 kb) form of TCR-beta mRNA were revealed.(ABSTRACT TRUNCATED AT 400 WORDS)

Presence of Epstein-Barr virus DNA in nasal lymphomas of B and 'T' cell type

We studied 12 tumours from 11 Chinese patients with primary nasal lymphoma for presence of Epstein-Barr Virus (EBV) DNA, using Southern-blot analysis. These results were correlated with immunophenotype and T-cell receptor (TcR) or immunoglobulin gene rearrangement patterns. EBV DNA was detected in all nine tumours with a 'T' phenotype, in both primary and secondary sites. When the structure of the viral genomic termini was studied using the EcoRI-Dhet probe, a single clonal episomal band was demonstrated in five tumour samples, with one other case showing a biclonal pattern. However, none of these cases showed clonal rearrangement of TcR beta chain gene, and TcR gamma rearrangement was found only in one. The lineage of these phenotypic 'T' lymphomas therefore require further studies for confirmation. Two out of three B-lymphomas were also EBV DNA+; clonal EBV DNA was found in one. Their B-lineage was confirmed by detection of clonal immunoglobulin gene rearrangements. The association of EBV with an increasing number of lymphomas of different types highlights the need for continued study into its role in oncogenesis.

Quantitative changes in T cell DNA methylation occur during differentiation and ageing

DNA methylation is one of the mechanisms involved in the regulation of developmentally relevant genes. Previous experiments demonstrated that T cells treated with DNA methylation inhibitors reacquire some of the phenotypic and functional characteristics of thymocytes, suggesting that DNA methylation may be involved in regulating some of the changes in gene expression during thymic maturation. To further examine whether changes in DNA methylation occur during T cell differentiation, total DNA deoxymethylcytosine content was compared in human thymocyte subsets and mature T cells. A significant increase in deoxymethylcytosine was found at the end of T cell differentiation which then decreased with age. These results suggest that increased DNA methylation may serve to silence genes following T cell differentiation. The results also raise the possibility that age-related decreases in T cell DNA methylation may contribute to changes in T cell function occurring in the elderly.

Characterization of gamma/delta T cell clones isolated from human fetal liver and thymus

The origin and development of T cells bearing gamma/delta T cells receptors (TcR) has been extensively studied in the mouse. By contrast, little is known about development patterns and diversity of the human gamma/delta T cell lineage. To study the repertoire of human gamma/delta+ T cells during T cell ontogeny, we have isolated clonal populations of gamma/delta+ T cells from 14-week fetal thymus and liver and characterized the molecular composition of their TcR. The technique of in situ hybridization was used to identify cells expressing TcR genes in fetal liver and thymus. A panel of clones representative of developing T cell populations found in vivo was subsequently isolated from both tissues and clones expressing cell surface gamma/delta receptors were identified. Although both the liver-derived gamma/delta+ T cell clone, L2, and the thymus-derived gamma/delta+ T cell clone, T6, had similar cell surface phenotypes, namely CD3+, CD7+, CD45+ and CD8-, their reactivity with anti-CD2 and -CD4 antibodies was different. L2 was CD2high, CD4- whereas T6 was CD2low, CD4low. Both clones possessed effector functions similar to those of adult T cells as demonstrated by the synthesis and secretion of cytokines in response to stimulation through the CD3/TcR complex. Analysis of the TcR composition of the fetal clones showed both clones to possess similar or identical gamma chain components, C gamma 1, J gamma 1/2, V gamma 8, and both utilize V delta gene segments other than V delta 1. This TcR genotype has not been previously reported in the analysis of adult gamma/delta+ T cells. Our studies have identified a unique population of human gamma/delta+ T cells that may be derived extrathymically and appear to be preferentially and perhaps transiently expressed during fetal life.

Aggressive natural killer cell leukaemia/lymphoma: report of four cases and review of the literature. Possible existence of a new clinical entity originating from the third lineage of lymphoid cells

The morphologic, immunologic, genotypic and functional properties of peripheral blood and bone marrow cells or cultured cells from four patients with a clinically aggressive non-T, non-B natural killer cell leukaemia/lymphoma (ANKL/L) are described. The leukaemic cells possessed medium to large granules in the cytoplasm, antigens against CD38, CD2, OKIa 1 and NKH-1 CD56) monoclonal antibodies on their cell-surface, and also showed natural killer (NK) activity. In addition, these ANKL/L belonged to neither T- nor B-cell lineage, proved by studying clonal gene rearrangement for the T beta, T gamma and T delta receptors, and immunoglobulin. After comparing them with the seven cases of ANKL/L reported in other institutions, with regard to immunophenotype, genotype and function, we conclude that ANKL/L originating from a third lineage of lymphoid cells is a distinct clinical entity.

Association of scleroderma with a T cell antigen receptor gamma gene restriction fragment length polymorphism

Restriction fragment length polymorphisms (RFLPs) in the T cell receptor (TCR) alpha, beta, and gamma genes were analyzed in 61 scleroderma patients and 150 controls. An association was found between scleroderma and an 11.3-kb Pvu II fragment in the TCR gamma gene; this gene was found in 41.0% of the patients, compared with 21.7% of the controls (P less than 0.01, odds ratio = 2.50). There were no associations between scleroderma and the tested RFLPs in the TCR alpha or beta genes, and no RFLPs were found in the constant region of the TCR delta gene.

Rearrangement of the T-cell receptor alpha, beta and gamma chain genes in chronic lymphocytic leukemia

Simultaneous expression of mature B-cell and T-cell markers and subsequent abrogation of expression of the T-cell surface markers by cytotoxic chemotherapy was reported earlier in a patient (TG) with chronic lymphocytic leukemia (CLL). In addition to rearrangements of the immunoglobulin (Ig) gene loci correlating with phenotypic data, the T-cell receptor (TCR) alpha, beta and gamma chain genes also displayed clonal rearrangements in peripheral blood lymphocyte DNA of TG. The present case shows that in CLL cells not only the expression of B-cell and T-cell specific differentiation antigens but also the rearrangement of Ig as well as TCR alpha, beta and gamma genes may occur simultaneously.

The T-cell receptor alpha, beta and gamma polymorphism in Japanese

Polymorphism in the genes encoding the alpha (alpha), beta (beta) and gamma (gamma) chains of the human T-cell receptors was analyzed both in population and family studies. Against twelve unrelated Japanese, several out of the 15 restriction endonucleases tested, revealed restriction fragment length polymorphism. The segregation of the polymorphic fragments were confirmed among 15 members of three families. In most of the cases paternal and/or maternal haplotypes could be assigned. By testing the polymorphic enzymes among the random healthy Japanese, the frequency of each polymorphic fragment was then determined. Although the polymorphism found in this study was similar to that reported in Caucasians, some differences were observed. Such differences are discussed. The restriction fragment length polymorphism in both population and family studies, derived from alpha, beta and gamma chains of the T-cell receptor found in this report, might be useful markers for genetic analysis of the T-cell function in relation to immunological disorders.

T cell receptor gene expression in sheep: differential usage of TcR1 in the periphery and thymus

We have isolated cDNA clones for each chain of the sheep T cell receptor (TcR) and used these to analyze TcR gene expression in thymocyte and peripheral T cell subsets. Outer cortical thymocytes expressed a low level of mature message for all TcR chains suggesting that intrathymic precursors for the alpha/beta and gamma/delta lineages occur in this population. Inner cortical and medullary thymocytes expressed high levels of mature alpha/beta transcripts, low levels of mature delta transcripts but no detectable gamma message. Mature alpha/beta transcripts were detected in peripheral CD4+ lymphocytes and these as well as CD8+ cells expressed a surface heterodimer of 85 kDa which resolved into 40- and 50-kDa subunits after reduction. Peripheral CD4-CD8-lymphocytes, which in sheep are marked by the T19 antigen and may account for up to 60% of T cells in blood, expressed a surface heterodimer of 75 kDa. The T19+ cells had high levels of mature delta and truncated beta transcripts in their cytoplasm but did not express the C gamma gene detected in DN thymocytes, although they seem to share V gamma and/or J gamma elements. Both forms of the sheep TcR are associated with CD3 molecules on the cell surface. These results show that (a) in contrast to the situation in rodents and humans, a large proportion of peripheral sheep lymphocytes use TcR gamma/delta; (b) the proportion of T cells in the periphery which use TcR gamma/delta is greater than in thymus; and (c) CD4-CD8- cells in thymus and periphery (T19+) use the same C delta gene but appear to use different C gamma genes, suggesting that in sheep there may be more than one lineage of lymphocytes expressing TcR gamma/delta.

cDNA cloning of functional T cell receptor gamma/delta chains expressed in human peripheral blood lymphocytes

We have identified in earlier studies two V delta rearrangements corresponding to a 4.5-kb Eco RI fragment detected with a V delta1 probe and to a 7-kb Eco RI band detected with a V delta2 probe. These rearrangements have been found in two human T cell clones, F6C7 and G6, displaying surface phenotypes unfrequent in human peripheral blood, namely Ti gamma A+ BB3- (F6C7) and Ti gamma A- BB3+ (G6). Herein, we report the sequences of the functional transcripts encoded by these rearranged genes and show that the 4.5- and the 7-kb Eco RI fragments correspond to V1/D3/J delta 3 and to V2/D3/J delta 3 recombinations, respectively. In addition, we have sequenced the V2/D3/J1/C delta transcripts expressed in two clones, AB12 and VTC, which have a Ti gamma A+ BB3+ surface phenotype corresponding to that of most gamma/delta peripheral lymphocytes. Analyses of the delta transcripts expressed by these four cells further strengthen the hypothesis that anti-BB3 and anti-delta-TCS-1 monoclonal antibodies recognize a V delta 2- and a V1/(D)/J delta 1-encoded epitope, respectively. Sequence of the gamma transcripts expressed by AB12 and F6C7 cells shows that they encode a V9/JP/C gamma 1 chain. Finally, we confirm that non-combinatorial diversity in the gamma and delta proteins is generated by both junctional flexibility and N-region addition without any somatic mutation.

The human T-cell receptor gamma (TRG) genes

The human T-cell receptor gamma (TRG) chain genes, like those encoding the T-cell receptor alpha- and beta-polypeptides, undergo rearrangements specifically in T cells. The human TRG locus, which has been completely mapped, is composed of two constant region genes (TRGC), five joining segments (TRGJ) and at least 14 variable gamma-genes (TRGV). Eight variable genes are functional and belong to four different subgroups. The product of the rearranged TRG gene is the gamma-chain which is expressed, along with the delta-chain, at the surface of a subset of T lymphocytes. Although some gamma delta + cells display a cytolytic activity, their precise function remains to be elucidated.

Developmental biology of T cell receptors

T cell receptors are the antigen-recognizing elements found on the effector cells of the immune system. Two isotypes have been discovered, TCR-gamma delta and TCR-alpha beta, which appear in that order during ontogeny. The maturation of prothymocytes that colonize the thymic rudiment at defined gestational stages occurs principally within the thymus, although some evidence for extrathymic maturation also exists. The maturation process includes the rearrangement and expression of the T cell receptor genes. Determination of these mechanisms, the lineages of the cells, and the subsequent thymic selection that results in self-tolerance is the central problem in developmental immunology and is important for the understanding of autoimmune diseases.

T cell function and expression are dramatically altered in T cell receptor V gamma 1.1J gamma 4C gamma 4 transgenic mice

We have characterized transgenic mice carrying a functional T cell receptor (TCR) C gamma 4 (V gamma 1.1J gamma 4C gamma 4) gene. Results indicate that active transcription of the C gamma 4 transgene can influence expression of the endogenous C gamma 4, C gamma 1 (V gamma 3-, V gamma 4-, V gamma 2-, or V gamma 5J gamma 1C gamma 1) and C gamma 2 (V gamma 1.2J gamma 2C gamma 2) genes, while the ultimate expression of other TCR delta, alpha, and beta chain genes, as well as the adult T cell response, are relatively unaltered. Cells expressing transgenic C gamma 4 and endogenous delta TCR transcripts can migrate to the skin as dendritic epithelial cells (DEC) even though C gamma 4 cells are rarely, if at all, found in the skin. Transgenic and control mice were compared at 2 weeks, 6-7 weeks, and older. At 2 weeks, the thymus of transgenic mice, particularly the medulla, was much larger than control. Moreover, peripheral lymphoid tissues of younger mice were markedly (as much as 100-fold) more immunoreactive (both Con A response and alloreactivity). These differences, although persistent, became smaller in older mice. The data suggest that transgene expression has a major effect on T cell development and reactivity.

Rearrangement of variable region T cell receptor gamma genes in acute lymphoblastic leukemia. V gamma gene usage differs in mature and immature T cells

Using probes recognizing variable regions (V gamma) and joining regions (J gamma) of the T cell receptor (TCR) gamma gene, we have analyzed the usage of V gamma genes in 24 patients with T cell acute lymphoblastic leukemia (ALL) and 36 patients with B-precursor ALL. In CD3- T-ALL derived from immature T cells, V gamma genes more proximal to J gamma were frequently rearranged; V gamma 8, V gamma 9, V gamma 10, and V gamma 11 were used in 19 of 24 rearrangements. In contrast, CD3+ T-ALL derived from a more mature stage of T cell ontogeny, showed a high frequency of rearrangements involving V gamma genes distal to J gamma; V gamma 2, V gamma 3, V gamma 4, and V gamma 5 were used in 17 of 25 rearrangements. In B-precursor ALL, no notable bias of V gamma gene usage was observed. This probably reflects the possibility that TCR genes may not rearrange according to a T cell hierarchy when under control of a B cell gene program. Furthermore, deletions of those V gamma genes located 3' to rearranged V gamma genes were observed in all patients analyzed. This supports the theory that loop deletion is a major mechanism for TCR-gamma gene rearrangement.

Characterization of T-cell-receptor gamma (TRG) gene rearrangements in alloreactive T-cell clones

Rearrangements of the T-cell Rearranging Gene (TRG) or T-cell-receptor gamma-chain genes were analyzed in 24 in vivo-sensitized alloreactive T-cell clones. This analysis represents the first complete assignment of TRG gene rearrangements to given variable and joining gene segments in nonleukemic T cells and provides some evidence for the hypothesis of sequential gamma genes rearrangements during T-lymphocyte differentiation. TRG gene rearrangements in our T-cell panel involved the known "active" V gamma genes, with a preferential use of V2 and V4 genes. In most clones, rearrangements occurred on both chromosomes and involved the J2 segment, but only 2 and 4 out of the 49 described rearrangements involved the additional J gamma segments JP1 and JP2, respectively. Two peculiar rearrangements were found. The first one was probably due to the creation of a new restriction enzyme site in the N-region at the V-J junction; the second can be explained by an aberrant rearrangement of a V gene to a sequence located between exons 2 and 3 of the TRGC1 gene.

T cell receptors

Over the past few decades, a solid body of evidence has been built up linking certain autoimmune diseases to the presence of specific major histocompatibility complex haplotypes. Major histocompatibility complex products are used by the immune system to distinguish non-self from self and are important in the recognition of foreign antigen by T cells. T cells play a number of roles in the initiation and control of the immune response, leading to the suggestion that T cells may be important in the genesis of these diseases. T cell recognition is mediated by a heterodimeric cell surface receptor, the T cell antigen receptor. A better understanding of the molecular biology of this receptor may shed some light on the cellular and molecular processes involved in the initiation and progression of these diseases.

T cell receptor delta gene rearrangements in acute lymphoblastic leukemia

Using a newly isolated cDNA clone encoding the TCR-delta gene and genomic probes, we have analyzed T cell receptor (TCR) delta gene rearrangement in 19 patients with T cell acute lymphoblastic leukemia (T-ALL) and 29 patients with B-precursor ALL. Five out of seven CD3- T-ALL and 4 of 12 CD3+ T-ALL showed bi-allelic rearrangements of the TCR-delta gene. In three CD3+ patients, a single allelic TCR-delta gene rearrangement was observed with rearrangement of the TCR-alpha gene on the other allele. In five CD3+ patients with bi-allelic rearrangements of the TCR-alpha gene, the TCR-delta gene locus was deleted. Transcription of the TCR-delta gene was also analyzed in six T-ALL. Five patients expressed TCR-delta transcripts. Only one T-ALL, presumably derived from the most immature T lineage cells, did not have TCR-delta transcripts, but expressed TCR-gamma and 1.0-kb truncated TCR-beta transcripts. In B-precursor ALL, 20 patients (69%) showed rearrangements of the TCR-delta gene. The frequency of TCR-delta gene rearrangement was higher than TCR-alpha (59%), gamma (52%), or beta (31%) genes. These findings suggest that TCR-alpha gene rearrangements may take place after rearrangements of the TCR-delta gene with concomitant deletion of rearranged TCR-delta genes in T cell differentiation. Among leukemic cells of B lineage, the TCR-delta gene is the earliest rearranging TCR gene, followed by TCR-gamma and beta gene rearrangements.

Involvement of the interleukin 2 pathway in the rearrangement and expression of both alpha/beta and gamma/delta T cell receptor genes in human T cell precursors

In this report, we have undertaken the phenotypic, functional and molecular characterization of a minor (less than 5%) subpopulation of adult thymocytes regarded as the earliest intrathymic T-cell precursors. Pro-T cells were immunoselected and shown to express different hematopoietic cell markers (CD45, CD38, CD7, CD5) and some activation-related molecules (4F2, Tr, HLA class II), but lack conventional T cell antigens (CD2-1-3-4-8-). TCR-gamma RNA messages are already expressed at this early ontogenic stage, while alpha and beta chain TCR genes remain in germline configuration. In vitro analyses of the growth requirements of pro-T cells demonstrated the involvement of the IL-2 pathway in promoting their proliferation and differentiation into CD3+ CD4+ or CD8+ mature thymocytes. Moreover, during the IL-2-mediated maturation process rearrangements and expression of both alpha and beta chain TCR genes occurred, and resulted in the acquisition of alpha/beta as well as gamma/delta (either disulphide-linked or non-disulphide-linked) heterodimeric TCR among the pro-T cell progeny.

Immunoglobulin epitopes defined by synthetic peptides corresponding to joining region sequence: conservation of determinants and dependence upon the presence of an arginyl or lysyl residue for cross-reaction between light chains and T-cell receptor chains

Joining or J region sequences of rearranging immunoglobulins and T-cell receptors show considerable sequence homology, particularly in their C-terminal portion corresponding to the fourth framework region of immunoglobulin variable regions. In order to test the question of whether serological cross-reactions between immunoglobulin variable regions and T-cell receptors were due to antigenic similarities in their J regions, we synthesized synthetic peptides corresponding to immunoglobulin J regions and to J regions predicted from gene sequence of the T-cell receptor beta chain. We found that antibodies produced against a synthetic 16-mer J beta sequence reacted with T-cell receptor chains and also with immunoglobulin light chains. The cross-reactivity was dependent upon the J signature sequence FG()GT(R or K)L where the presence of a positively charged lysyl or arginyl residue was essential for cross-reactivity. We were able to classify J region determinants into two distinct antigenic sets; one corresponding to JH and the other corresponding to J kappa, J lambda, J beta and J alpha. Although considerable homology occurs between JH and JL (or J beta) sequences, little cross-reactivity was observed between these two J subsets. Antibodies raised against polyclonal murine IgG immunoglobulins contained antibody subpopulations specifically reactive with either JH or J beta peptides. The serological data derived here using antipeptide antibodies are consistent with computer modeling studies that indicate that the conformations of T-cell receptor variable regions resemble those of classical immunoglobulins. Our data comparing cross-reactivities restricted to the J region indicate that the expression of the J region by intact T-cell receptor beta chains is probably more similar to that of light chains than it is to the corresponding region of heavy chains.