T-cell Antigen Receptor Beta-chain Research Articles

Complete nucleotide sequence of primitive vertebrate immunoglobulin light chain genes.

Antibody to Heterodontus francisci (horned shark) immunoglobulin light chain was used to screen a spleen cDNA expression library, and recombinant clones encoding light chain genes were isolated. The complete sequences of the mature coding regions of two light chain genes in this phylogenetically distant vertebrate have been determined and are reported here. Comparisons of the sequences are consistent with the presence of mammalian-like framework and complementarity-determining regions. The predicted amino acid sequences of the genes are more related to mammalian lambda than to kappa light chains. The nucleotide sequences of the genes are most related to mammalian T-cell antigen receptor beta chain. Heterodontus light chain genes may reflect characteristics of the common ancestor of immunoglobulin and T-cell antigen receptors before its evolutionary diversification.

A polyclonal CD4+ and CD8+ lymphocytosis in a patient doubly infected with HTLV‐I and HIV‐1: A clinical and molecular analysis

HTLV-I is associated with adult T-cell leukemia/lymphoma (ATL) characterized by monoclonal expansions of CD4+ T-lymphocytes. In this report we describe a histologically benign, polyclonal HTLV-I infection in a patient exhibiting both an absolute CD4+ and CD8+ lymphocytosis. Three T-cell lines containing integrated HTLV-I proviral copies established from this patient were initially polyclonal, but with time all grew out the same two clones as determined by analysis of their T-cell antigen receptor beta chain gene rearrangements. The patient subsequently developed pulmonary and nasopharyngeal nodules containing HTLV-I infected cells. Restriction analysis of the patient's HTLV-I provirus revealed no differences from prototype HTLV-I and the tax gene was normally expressed in vivo and in vitro. The patient's T-lymphocytosis and HTLV-I+ pulmonary tract nodules were put into a complete clinical remission by treatment with alkylating agents and steroids. Subsequently, the patient developed a severe immunodeficiency state and expired. Retrospective serologic and gene amplification assays for HIV-1 demonstrated that he had been doubly infected from the time of presentation. Postmortem analysis by polymerase chain reaction revealed the presence of both HTLV-I and HIV-1 in lymphatic tissues and the testes; HIV-1 was also detected in brain tissue.

Positive selection of CD4+ thymocytes controlled by MHC class II gene products.

The mature T-cell antigen receptor repertoire is characterized by lack of reactivity to self-components as well as by preferential reactivity to foreign antigens in the context of polymorphic self-proteins encoded within the major histocompatibility complex. Whereas the former characteristic (referred to as negative selection or tolerance) is associated with intrathymic deletion of T cells expressing T-cell antigen receptor beta-chain variable (V beta) domains, which confer a preferential reactivity to self antigens, the existence of the latter (referred to as positive selection or MHC restriction) has so far only been inferred indirectly from functional studies. We show here that intrathymic deletion of V+beta 6 T cells (reactive with a self-antigen encoded by the Mlsa locus) is controlled by polymorphic MHC class II determinants. Furthermore, in mice lacking expression of Mlsa, the same class II MHC loci control the frequency of occurrence of V+beta 6 cells among mature CD4+ T lymphocytes. These data are direct evidence for positive selection by MHC determinants in the thymus in unmanipulated animals.

Nonlinkage of the T cell receptor alpha, beta, and gamma genes to systemic lupus erythematosus in multiplex families.

To test the possibility that T cell antigen receptor (TcR) genes are linked to the genes involved in the pathogenesis of systemic lupus erythematosus (SLE), genomic DNA restriction fragment length polymorphisms were studied, using the Southern blot technique, in 5 families with multiple members with SLE, 14 unrelated SLE patients, and 14 normal controls. Polymorphic patterns were detected with probes for all 3 TcR chains, but there was no significant difference in the distribution of the restriction fragment length polymorphism pattern among the patients, the relatives, and the controls. Furthermore, in the families with at least 2 individuals with the disease, each of the 3 TcR chain genes did not cosegregate with the disease. We conclude that TcR alpha, beta, and gamma chain genes are not likely to be linked to genes related to SLE.

DNA segment containing C beta 1, a gene for the constant region of the beta chain of the T-cell antigen receptor, was inserted into chromosome 6 in cells from one patient with human T-cell leukemia.

DNA rearrangements that occurred in the vicinity of T-cell antigen receptor beta-chain gene clusters residing on chromosome 7 were examined in human T-cell acute lymphoblastic leukemia cells. In one patient, it was observed that, for the T-cell receptor beta-chain genes, a D beta 1-J beta 2.3 (where D is diversity and J is joining) junction was found on one chromosome, while the other chromosome kept the germ-line configuration. If this D beta-J beta junction was formed by the customary deletion mechanism, the C beta 1 gene (where C is constant) located between the D beta 1 and J beta 2.3 loci should have disappeared from this chromosome. The C beta 1 gene indeed was absent from the rearranged chromosome 7, but it was found on chromosome 6 as an inserted segment. The implications of the observations are discussed.

Genotypic Analysis of Cutaneous T-Cell Lymphomas

The gene encoding the beta-chain of the T-cell antigen receptor (TCR) has been analyzed for evidence of rearrangement in skin, blood, and lymph node specimens from 23 cases of known or suspected cutaneous T-cell lymphoma (CTCL). Two cutaneous large cell lymphomas, 4 cases of Sézary syndrome, and 5 cases of advanced (tumor) stages of mycosis fungoides showed clonal rearrangement of the TCR beta-chain gene in all samples, including lymph nodes in which histologic examination revealed only dermatopathic lymphadenitis. These results indicate that DNA analysis provides a valuable means for improving the diagnosis of extracutaneous disease in advanced stages of CTCL. In contrast, the gene was in a germline configuration in all samples from 12 patients with plaque stages of mycosis fungoides or suspected early CTCL, suggesting that in these 2 conditions the T-cell proliferation is either polyclonal or contains very few monoclonal (i.e., neoplastic) cells.

Retroviral transduction of T-cell antigen receptor beta-chain and myc genes.

Support for multistage models of oncogenesis has been provided by several highly leukaemogenic retrovirus isolates that have transduced more than one host cell gene. Where functional studies have been performed, these retroviral oncogenes show synergy for in vitro transformation and leukaemogenesis. In naturally occurring feline leukaemias associated with feline leukaemia virus (FeLV), retroviral transduction of myc is a frequent oncogenic mechanism. But evidence suggesting that the FeLV v-myc genes might be insufficient for leukaemogenesis was provided by the latency (12 weeks) and clonality of FeLV/v-myc-induced tumours and the absence of demonstrable in vitro transformation by these viruses. In the search for secondary leukaemogenic events in FeLV/v-myc tumours, we have identified a case of FeLV transduction of a T-cell antigen receptor beta-chain gene. The proviruses carrying this gene (which we have named v-tcr) were a separate population from those carrying v-myc. In its normal role, the T-cell receptor beta-chain forms part of a multimeric complex involved in antigen recognition and T-cell activation. We suggest that v-tcr is a novel viral oncogene which assisted v-myc in the genesis of a naturally occurring case of thymic lymphosarcoma.

Functional alpha and beta T cell chain receptor messages can be detected in old but not in young athymic mice.

The expression and sequences of T cell antigen receptor (TcR) alpha and beta-chain genes were investigated in the spleens from congenitally athymic (nude) mice. A small number of Thy-1+ cells (approximately 7.0%) was found in nylon wool-enriched spleen cells from young (8 weeks old) nude mice but no L3T4 or Lyt-2 surface antigens were detected. These nude mice expressed only a low level of 1.0-kb beta-chain mRNA and little or no alpha-gene transcripts. On the other hand the number of Thy-1+ spleen cells increased slightly (to 24%) in old (20 weeks old) nude mice and a small number of L3T4+ (10%) and/or Lyt-2+ (5%) cells were detectable. "Full length" 1.7-kb alpha-chain and 1.3-kb beta-chain messages could be found in nylon wool-enriched spleen cells from old nude mice. Sequence analysis of the cDNA revealed that no functional alpha and beta-chain genes can be detected in the spleen cells of young athymic mice while some of the old mice with nu/nu genotype are composed of completely rearranged V-(D)-J-C-gene segments which encode potentially functional proteins. Interestingly, two of three independent cDNA clones encoding the alpha chain used the same V alpha and J alpha-gene segments. These results suggest that extrathymic TcR alpha and beta-chain gene rearrangements do occur, though slowly, to some extent, in nude mice and may be responsible for the limited antigen and/or H-2-related T cell functions in these old athymic mice. The data further suggests that the TcR repertoire in athymic mice may also be limited.

Viral transduction of host genes in naturally occurring feline T-cell leukaemias: transduction of myc and a T-cell antigen receptor beta-chain gene.

Feline leukaemia virus has been a particularly useful tool in cancer research since many of the naturally occurring tumours associated with this virus group have yielded recombinant retroviruses containing hostderived oncogenic information. The prevalence of transduction as an oncogenic mechanism was seen first in multicentric fibrosarcoma, a relatively rare tumour in FeLV-infected cats (Hardy et al. 1982; Besmer 1984). In a significant percentage of cases of this disease, oncogene-containing feline sarcoma viruses have been identified. More recently, we and others have found that in the more common FeLV-associated neoplasm, thymic lymphosarcoma, viral capture of the c-myc gene can occur (Neil et al. 1984; Levy et al. 1984; Mullins et al. 1984). Since the oncogenes carried by feline sarcoma viruses do not include myc, these reports provided the first evidence that myc may be a target for oncogenic activation by FeLV.KeywordsViral TransductionFeline Leukaemia VirusAntigen Receptor GeneProviral InsertionAntigen Receptor Gene RearrangementThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Transformation of T-lymphoid cells by Abelson murine leukemia virus.

Abelson leukemia virus (A-MuLV) is an oncogenic murine retrovirus whose genome contains sequences homologous to those of a normal cellular gene, c-abl. It has been demonstrated to cause rapid transformation of several cell types, including pre-B lymphocytes, macrophages, and fibroblasts. More recently, A-MuLV has been reported to induce thymic tumors in a mouse strain (C57BL/Ka) previously thought to be resistant to disease induction. We showed that the masses occurring after intrathymic injection of the virus were composed of lymphocytes of a previously described immature T-cell phenotype. This phenotype has been defined here by flow cytometry of 10 primary tumor samples stained with antibodies to several thymocyte differentiation antigens. Hybridization of DNAs from these tumors with v-abl, immunoglobulin mu, and T-cell antigen receptor beta-chain probes confirmed the T-lymphoid, polyclonal nature of the primary tumor cells. The primary tumors were malignant, as clearly shown by reinjection into Thy-congenic host animals. Further, four Thy- in vitro cell lines derived from three tumors differed from the majority of primary tumor cells and were similar to previously described A-MuLV-transformed pre-B cells. The consistent T-lymphoid phenotype exhibited by primary A-MuLV thymomas may represent one stage of normal thymocyte differentiation.

Abnormal recombination products result from aberrant DNA rearrangement of the human T-cell antigen receptor beta-chain gene.

Two unusual rearrangements of the T-cell antigen receptor beta-chain gene have occurred in the human T-cell tumor line CEM. The beta chain of the T-cell antigen receptor is encoded in germ-line DNA by immunoglobulin-like gene segments that rearrange during the somatic development of T cells to form active genes. Structural analysis of rearranged immunoglobulin genes has already revealed a great deal about the mechanisms by which these genes rearrange. To further characterize the mechanism by which beta-chain genes rearrange, we have determined the organization of the rearranged beta-chain gene segments in the human T-cell tumor line CEM. Three rearranged joining (J) or diversity (D) segments of the beta-chain gene are found in CEM. One of these segments rearranged during the formation of a normal rearranged beta-chain gene that comprises a variable (V beta), D beta, and J beta gene segment associated with a constant region gene segment. Two abnormal recombination products are found at the other rearranged beta-chain locus. One product has the structure, J beta-D beta-J beta, with the J beta gene segments joined in a head-to-head fashion, while the other one consists of a V beta-D beta recombined segment not associated with a J beta gene segment. We propose that the J beta-D beta-J beta structure was formed by an inversion of 6 kilobases of DNA and subsequently, a V beta-D beta rearrangement occurred. The presence of these products in CEM has important implications for our understanding of the mechanism by which somatic rearrangements of beta-chain gene segments occur.

Change in antigen specificity of cytotoxic T lymphocytes is associated with the rearrangement and expression of a T-cell receptor beta-chain gene.

Cloned H-Y-specific murine cytotoxic T lymphocytes, which alter antigen specificity in vitro ("aging"), simultaneously exhibit changes in the T-cell antigen receptor beta-chain rearrangements and respective mRNAs expressed. beta-chain cDNA clones were isolated from a library prepared from mRNA of aged killer T cells. The sequence of the beta-chain variable region element (VAK) was found to be identical with germ-line DNA. Four bases at the beta-chain diversity-joining region (D beta--J beta) junction cannot be explained by known germ-line D beta and J beta elements. These results illustrate that in T-cell clones altered antigen specificity correlates with a switch in productive beta-chain rearrangements of the T-cell receptor. When tested for its expression under physiological conditions, significant levels of VAK mRNA were found in normal lymphocyte populations.

Reconstitution of an active surface T3/T-cell antigen receptor by DNA transfer.

We have introduced a full-length complementary DNA of the T-cell antigen receptor beta-chain into a mutant human T-cell line that lacked a complete beta-chain messenger RNA, had a diminished level of alpha-chain transcript and did not express surface T3- or antigen receptor. Expression of the transfected beta-chain led to a normal level of alpha-chain transcript and a structurally and functionally active T3 T-cell antigen receptor complex on the cell surface.

Sequence and expression of transcripts of the human T-cell receptor beta-chain genes.

T lymphocytes can produce mRNAs from the first or second constant region of the T-cell antigen receptor beta-chain. A 1.3-kilobase (kb) transcript encoding the mature protein contains V, J and one of the two C region sequences, but does not always contain D sequences. A 1.0-kb mRNA, found mainly in immature T cells, does not contain V sequences and can result from transcription that initiates upstream from an unrearranged J element.