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H Acha-Orbea

Publications and source records attributed to H Acha-Orbea.

98 records · Page 6Linked to original sources
PubMed1987

Fine specificity and T-cell receptor beta-chain gene rearrangements of five H-2Db-specific cytotoxic T-cell clones.

A panel of cytotoxic T lymphocyte clones that recognize H-2b target cells has been established. Six different clones were distinguished according to the following criteria. First, the fine specificity of the clones was determined by testing proliferation and cytotoxicity on target cells of recombinant mice. Clone 221 recognized H-2Kb, and five other clones recognized H-2Db. Clone 433 distinguished itself from the other five Db-specific clones by cross-reacting with an antigen on H-2k cells. Second, the presence of an idiotypic determinant as defined by the 3F9 clone-specific monoclonal antibodies was investigated in cytotoxicity inhibition experiments. One of the Db-specific clones, 653, was inhibited by these antibodies and was therefore clearly different from the other Db-specific clones. The third criterion involved the rearrangement pattern of the DNA coding for the beta chain of the T-cell receptor. Southern blot analysis showed that each clone had a unique pattern. Interestingly, clone 653, which expresses the same idiotypic determinant as clone 3F9, had deleted the C beta 1 gene cluster, whereas this gene is functionally expressed in clone 3F9.

Animals↗
PubMed1987

The first external domain of the nonobese diabetic mouse class II I-A beta chain is unique.

The nonobese diabetic mouse is recognized as an important animal model for human insulin-dependent diabetes mellitus. One of the components of susceptibility to this disease has been mapped to the major histocompatibility complex. In this study, full-length cDNA clones encoding the I-A alpha and beta chains from the nonobese diabetic mouse have been isolated and sequenced. They are identical to the sequences previously determined from the H-2d haplotype except for the sequence encoding the first external domain, the leader peptide, and the 5' untranslated region of the I-A beta chain molecule. Most strikingly, there are five consecutive nucleotide substitutions which lead to two radical amino acid changes in a region that is conserved between human and mouse. We suggest that the unique structure of the first external I-A beta chain domain is a major determinant in the disease susceptibility that maps to the major histocompatibility complex of the nonobese diabetic mouse.

Amino Acid Sequence↗
PubMed1985

Cytotoxic T cell clone-specific monoclonal antibodies used to select clonotypic antigen-specific cytotoxic T cells.

Two rat monoclonal antibodies (mAb) have been produced which recognize a clone-specific determinant on the alloreactive cytotoxic T lymphocyte (CTL) clone 3 F9. CTL clone 3F9 of BALB/c origin is specific for H-2Db and can be grown by weekly restimulation with irradiated stimulator spleen cells expressing H-2Db in the presence of interleukin 2. Two mAb against T cell clone 3F9, 44-22-1(IgG2a) and 46-6 B5(IgM), have been proven to be clone specific: they inhibit cytotoxic activity of 3F9 only and bind specifically to 3 F9 when compared in a panel of different CTL clones, or cells from different mixed lymphocyte cultures (MLC), BALB/c thymus and spleen cells. The mAb 44-22-1 has been used to sort cells from a primary MLC BALB/c anti-H-2Db by fluorescence-activated cell sorter (FACS) to select CTL expressing 3 F9 clonotype-specific determinants. The lymphocytes reactive with 44-22-1 represent a minor subpopulation of the CTL of the primary MLC. The specific alloreactive cytotoxicity of unsorted lymphocytes of the bulk primary MLC could not be inhibited by the mAb 44-22-1 and 46-6 B5 whereas the sorted 3 F9 clonotype-positive cultures could be inhibited very effectively. All the CTL clones derived from the FACS-sorted clonotype-positive culture show all the same properties and are identical with clone 3 F9 with respect to antigen-specific cytotoxicity, inhibition of cytotoxicity by the mAb and surface markers.

Animals↗
PubMed1983

Characterization of cloned cytotoxic lymphocytes with NK-like activity.

Cloned H-2b-restricted male antigen-specific cytotoxic T cells were kept in culture in the presence of IL 2 for over 2 yr. During this time, they lost their antigenic specificity and now exhibit high NK-like activity. Three separate clones HY 1, HY 2, and HY 3 and their subclones, when tested on a panel of NK-sensitive and NK-insensitive target cells, showed typical lysis patterns of NK cells. Three cytotoxicity-loss mutants were obtained by subcloning. At least one of these cytotoxicity-loss mutants still exhibited binding to NK-sensitive target cells. The various HY clones were compared with cloned alloreactive cytotoxic T cells of B10 anti-B10.D2 specificity with respect to surface markers, target specificity, kinetics of lysis, morphology, and influence of monoclonal antibodies and chemicals on cytotoxicity. Only one major difference between cloned NK-like and alloreactive T cells was detected: monoclonal anti-Lyt-2 antibodies inhibited cytotoxic activity of alloreactive T cells but not of NK-like cells, although both expressed Lyt-2 on their surface. Morphologically, HY cells were characterized by numerous lysosomal granules in their cytoplasm. Clones with NK-like activity differed from cytotoxicity-loss mutants by both ultrastructural appearance and enzyme histochemistry of lysosomes. Interaction of NK-like cells with YAC-1 cells induced membrane lesions of variable size in target cells. Effects of chemicals influencing lysosomal pathways such as monensin, NH4Cl, and chloroquine on cytotoxicity were investigated. Monensin as well as NH4Cl inhibited cytotoxicity of NK as well as alloreactive clones, whereas chloroquine did not. Spleen cells from acutely virus-infected mice with high NK reactivity showed the same behavior except for chloroquine, which was slightly inhibitory. The addition of monensin to the cells resulted in morphologic changes in the lysosomal granules. These data strongly suggest that NK-like killing is triggered by unknown substance(s) released from lysosomes of effector cells. Cloning of antigen-specific cytotoxic T cells under conditions of limiting dilution and continuous growing in medium containing Con A supernatant but not the relevant antigen often leads to loss of specificity and appearance of NK-like activity. The results presented are representative of a great amount of work in this and probably many other laboratories attempting to clone cytotoxic effector T cells.

Animals↗
PubMedDate not supplied

Limited heterogeneity of autoantigens and T cells in autoimmune diseases?

For many induced and spontaneous autoimmune diseases, a predominant role for T cells in the organ-specific destruction process has been shown. In one of the induced models of autoimmunity, experimental allergic encephalomyelitis (EAE), a very small heterogeneity of T-cell receptor (TcR) molecules is expressed by the pathogenic T cells in both rats and mice. Contrary to induced autoimmune diseases, little is known about the autoantigens recognized by these autoimmune T cells and the heterogeneity of their TcR in spontaneous autoimmune diseases. The aim of this work was to establish a system which allows characterization of relevant autoantigens in spontaneous insulin-dependent diabetes mellitus (IDDM) in non-obese diabetic (NOD) mice. A completely different approach was taken to characterize the gene products of the minor lymphocyte stimulatory (Mls) loci. These gene products are responsible for the clonal elimination or the clonal stimulation of T cells expressing particular TcR V beta genes and therefore could be implicated in induction of autoimmune diseases by oligoclonal T-cell populations. The finding that Mls antigens are encoded by retroviral sequences leads to the hypothesis that viruses could be the inducing agents of autoimmune diseases.

Animals↗
PubMedDate not supplied

Roles of superantigens in microbial infections?

Superantigens have been defined in a variety of infectious particles such as bacteria and viruses. These superantigens have the capacity to stimulate a large percentage of the host T cells by interacting specifically with the T-cell receptor V beta chain which is shared by about 1-20% of mature T cells. The recent discovery that mammary tumour viruses express such superantigens enabled the analysis of the retroviral life cycle and led to questions about the role of superantigen in amplification of the infection.

Animals↗
PubMedDate not supplied

Identical V beta T-cell receptor genes used in alloreactive cytotoxic and antigen plus I-A specific helper T cells.

T lymphocytes involved in the cellular immune response carry cell-surface receptors responsible for antigen and self recognition. This T-cell receptor molecule is a heterodimeric protein consisting of disulphide-linked alpha- and beta-chains with variable (V) and constant (C) regions. Several complementary DNA and genomic DNA clones have been isolated and characterized. These analyses showed that the genomic arrangement and rearrangement of T-cell receptor genes using VT, diversity (DT), joining (JT) and CT gene segments is very similar to the structure of the known immunoglobulin genes. We have isolated two cDNA clones from an allospecific cytotoxic T cell, one of which shows a productive V beta-J beta-C beta 1 rearrangement without an intervening D beta segment. This V beta gene segment is identical to the V beta gene expressed in a helper T-cell clone specific for chicken red blood cells and H-21. The other clone carries the C beta 2 gene of the T-cell receptor, but the C beta 2 sequence is preceded by a DNA sequence that does not show any similarity to V beta or J beta sequences.

Animals↗