Search PubMed⌕ Search

Biomedical subjects

S Tonegawa

Publications and source records attributed to S Tonegawa.

At least 145 records · Page 8Linked to original sources
PubMed1990

Transgenic mice demonstrate that epithelial homing of gamma/delta T cells is determined by cell lineages independent of T cell receptor specificity.

gamma/delta T cells with different TCR repertoires are compartmentalized in different epithelia. This raises the possibility that the TCR-gamma/delta directs homing of T cells to these epithelia. Alternatively, the signals that induce TCR-gamma/delta expression in developing T cells may also induce homing properties in such cells, presumably in the form of cell surface receptors. We have examined this issue by studying the homing of gamma/delta T cells in transgenic mice constructed with specific pairs of rearranged gamma and delta genes. In such mice, most gamma/delta T cells express the transgene-encoded TCR. We find that homing to both skin and gut epithelia is a property of T cells and is not determined by the type of gamma and delta genes used to encode their TCR. We also studied the effect of TCR replacement on the expression of Thy-1 and CD8 proteins on the gamma/delta T cells associated with gut epithelia. Our results show that the expression of the appropriate type of TCR-gamma/delta is not required for the Thy-1 expression by these T cells, suggesting that Thy-1 is not an activation marker. In contrast, CD8 expression by gut gamma/delta T cells seems to depend on the expression of the appropriate type of TCR.

Animals↗
PubMed1990

Self-tolerance to transgenic gamma delta T cells by intrathymic inactivation.

During their intrathymic differentiation, T lymphocytes expressing alpha beta T-cell receptors (TCR) are negatively and positively selected. This selection contributes to the establishment of self-tolerance and ensures that mature CD4+ and CD8+ cell populations are restricted by the self major histocompatibility complex. Little is known, however, about gamma delta T-cell development. To investigate whether selection operates in the establishment of the gamma delta T-cell class, we have generated transgenic mice using gamma- and delta-transgenes encoding a TCR that is specific for a product of a gene in the TL-region of the TLb haplotype. Similar numbers of thymocytes expressing the transgenic TCR were generated in mice of TLb and TLd haplotypes. But gamma delta thymocytes from TLb and TLd transgenic mice differed in cell size, TCR density and in their capacity to respond to TLb stimulator cells or interleukin-2 (IL-2). In contrast to gamma delta T cells from TLd transgenic mice, gamma delta T cells from TLb transgenic mice did not produce IL-2 and did not proliferate in response to TLb stimulator cells, but they did proliferate in the presence of exogenous IL-2. These results indicate that functional inactivation of self-antigen-specific T cells could contribute to the establishment of self-tolerance to thymic determinants.

Animals↗
PubMed1990

Homing of a gamma delta thymocyte subset with homogeneous T-cell receptors to mucosal epithelia.

In mice gamma delta T-cell populations with distinct T-cell receptor (TCR) repertoires and homing properties have been identified. Diversified populations are found in lymphoid organs and intestinal epithelia. By contrast, the gamma delta T-cells that have been found in the murine skin are homogeneous. They express a TCR consisting of one particular V gamma 5 and one particular V delta 1 chain and seem to originate from early fetal thymocytes. We have now systematically analysed many tissues by immunohistochemistry and TCR gene sequencing aided by the polymerase chain reaction. These studies revealed a second homogeneous gamma delta T-cell subset in epithelia not of the intestine and skin, but of the vagina, uterus and tongue. The TCR expressed by this gamma delta T-cell subset consists of the same V delta 1 chain. Cells that express this particular TCR have previously been shown to be positively selected in the late fetal thymus.

Animals↗
PubMed1990

Distribution of thymocytes expressing gamma delta receptors in the murine thymus during development.

We have examined the appearance of thymocytes expressing gamma delta TCR within the developing thymus by using immunohistochemical techniques and flow cytometry in conjunction with the mAb 3A10, which recognizes a determinant associated with the constant region of the delta-chain. gamma delta+ Cells were first detected at day 16 of gestation, attained maximal levels at day 17 of gestation, and declined thereafter. By using the Ulex europeus agglutinin to identify medullary epithelial cells in situ, we observed a striking colocalization of gamma delta+ thymocytes and U. europeus agglutinin-positive medullary epithelial cells during late fetal and neonatal periods of development. In the thymuses of adult mice, gamma delta+ thymocytes were scattered throughout cortical and medullary areas of the thymus and most concentrated in the subcapsular areas of the thymus. Ultrastructural immunohistochemistry confirmed the close association between medullary thymic epithelial cells and gamma delta+ thymocytes in the neonatal thymus and also showed that some TCR-gamma delta molecules were patched to areas of contact with medullary epithelial cells. In contrast to the cellular distribution of either CD3 molecules or the TCR-alpha beta, where extensive intracellular labeling of thymocytes has been observed, cytoplasmic accumulation of delta-chain was not detected.

Animals↗
PubMed1990

Positive selection of gamma delta T cells.

The issue of T-cell repertoire selection has been addressed recently by several laboratories. While evidence has been provided for both negative and positive selection of CD4+ and CD8+ alpha beta T cells, the molecular basis of positive selection remains unclear. In this article Juan Lafaille and colleagues describe molecular features of gamma delta T-cell selection in the fetal thymus. These features were deduced from extensive junctional sequence data of gamma delta T-cell receptor genes in fetal thymocytes. Their data suggest the active participation of a self peptide in the positive selection of gamma delta T cells.

Animals↗
PubMed1990

Selection of gamma delta T cells with canonical T-cell antigen receptors in fetal thymus.

Two gamma delta T-cell subsets that are generated in the fetal thymus and selectively localize in epidermis and uterus-vagina-tongue epithelia exhibit remarkable homogeneity in their (T-cell) antigen receptors (TCR). In the present study, we show that cells expressing the canonical gamma delta TCR are also generated in fetal thymus organ cultures. Treatment of these cultures with anti-gamma delta TCR antibodies did not prevent gamma delta T-cell development but led to a striking increase in the frequency of noncanonical in-frame sequences. We conclude from this finding that cells expressing the canonical TCR accumulate selectively as a result of TCR-mediated positive selection in the fetal thymus.

Animals↗
PubMed1990

T-cell receptor gamma delta and gamma transgenic mice suggest a role of a gamma gene silencer in the generation of alpha beta T cells.

A T lymphocyte expresses on its surface one of two types of antigen receptor, T-cell receptor alpha beta or T-cell receptor gamma delta, encoded by a pair of somatically rearranged alpha and beta or gamma and delta genes. It has been suggested that alpha beta T cells are generated only from precursor T cells that failed to rearrange gamma and delta genes in a functional form. However, we found that transgenic mice constructed with functionally rearranged gamma and delta genes produce a normal number of alpha beta T cells. The transgene gamma present in these alpha beta T cells is repressed apparently through an associated cis DNA element (silencer). We propose that some T-cell precursors are committed to generate alpha beta T cells independent of the rearrangement status of their gamma gene and that this commitment involves activation of a factor(s) that interacts with the gamma gene-associated silencer.

Animals↗
PubMed1989

Junctional sequences of T cell receptor gamma delta genes: implications for gamma delta T cell lineages and for a novel intermediate of V-(D)-J joining.

Nucleotide sequences of a large number of V-(D)-J junctions of T cell receptor (TCR) gamma and delta genes show that most fetal thymocytes express on their surface one of just two gamma delta TCRs known to be expressed by epidermal gamma delta T cells (s-IEL) or intraepithelial gamma delta T cells associated with female reproductive organs (r-IEL). In contrast, gamma delta TCRs expressed on adult thymocytes are highly diverse as a result of multiple combinations of gene segments as well as junctional deletions and insertions, indicating that developmental time-and cell lineage-dependent mechanisms exist that control the extent of gamma delta TCR diversity. In addition, this study revealed a new type of junctional insertion (P nucleotides), which led to a new model of V-(D)-J joining generally applicable to immunoglobulin and TCR genes.

Aging↗
PubMed1989

Diversity of gamma delta T-cell receptors on murine intestinal intra-epithelial lymphocytes.

The search for the genes encoding the T-cell receptor (TCR) alpha- and beta-subunits revealed a third gene gamma which shares with the alpha- and beta-genes several properties including somatic rearrangement. This gene, together with a fourth rearranging gene delta, encodes a second type of T-cell receptor, TCR gamma delta. Although TCR gamma delta-bearing T cells constitute a relatively minor subpopulation in the thymus and in peripheral lymphoid organs, they are the major lymphocytes of epidermis (dendritic epidermal cells or DEC) and of intestinal epithelium (intestinal intraepithelial lymphocytes or IEL) in mice, suggesting that at least some gamma delta T cells are important in the surveillance of a variety of epithelia. It was recently reported, however, that the TCR gamma delta on DEC has essentially no structural diversity, implying that the putative ligand is monomorphic. As this finding, if generally applicable, poses severe restrictions on the origin of the ligand, we investigated the diversity of the TCR on the second major epithelium-associated gamma delta T cells, namely IEL from mice. We report here that by contrast with the DEC gamma delta, the IEL gamma delta TCR are structurally diverse.

Animals↗
PubMed1989

T cell receptor-gamma and -delta genes preferentially utilized by adult thymocytes for the surface expression.

To assess the diversity of gamma delta receptors expressed on adult thymocytes we characterized the gamma- and delta-genes used in a panel of T cell hybridomas expressing a TCR-gamma delta-CD3 complex on the cell surface. DNA cloning and sequencing analysis were necessary to determine the used genes because of the presence of multiple rearrangements in these hybridomas. Among eight hybridomas analyzed, five used V gamma 4, two used V gamma 7, and one used V gamma 6 for gamma-genes, and four used V delta 5, two used V delta 4, and two used V delta 7 for delta-genes. The last delta-gene is documented for the first time. V gamma and V delta appear to pair randomly only restricted by the frequency of the utilization of individual V gamma and V delta segments. These gamma- and delta-genes contained N region addition between the V and J region in most cases. Both D delta 1 and D delta 2 regions were used in the most delta-genes as was seen previously. These results show that certain gamma- and delta-gene segments that are rarely used for the expression on fetal thymocytes are preferentially used by adult thymocytes. Also the repertoire of the gamma delta receptors on adult thymocytes is much greater than that on fetal thymocytes. BW5147 specific V4-C1 gamma-gene was expressed in all of the adult hybridomas. Inasmuch as this gene was not expressed in BW5147 cells or in fetal thymocyte hybridomas expressing V5 or V6 gamma genes, there exists a novel V gene segment-dependent control of transcription in the gamma-gene system.

Aging↗
PubMed1989

Monoclonal antibodies specific to native murine T-cell receptor gamma delta: analysis of gamma delta T cells during thymic ontogeny and in peripheral lymphoid organs.

Three hamster monoclonal antibodies (mAbs), all recognizing different epitopes present on the native form of the murine T-cell antigen receptor (TCR) gamma delta subunits, have been generated. mAb 3A10 is specific to a pan-murine TCR gamma delta, recognizing a C delta constant region determinant. mAb 8D6 is specific to a subset of T cells expressing V gamma 4- and V delta 5-encoded gamma delta TCR, and mAb 5C10 is clonotypic. Using these and other mAbs directed against a variety of T-cell surface markers, we quantitated and characterized gamma delta T cells present in developing thymuses as well as in the conventional lymphatic organs by flow cytometry. These studies revealed that (i) many gamma delta thymocytes and peripheral T cells bear CD4 and/or CD8 molecules, (ii) T cells bearing both alpha beta and gamma delta TCRs are scarce, and (iii) thymocyte subsets bearing TCR gamma delta encoded by different combinations of V gamma and V delta gene segments appear in waves during ontogeny.

Aging↗
PubMed1989

Recognition of a self major histocompatibility complex TL region product by gamma delta T-cell receptors.

Ligand specificity of a murine gammadelta T-cell receptor-expressing hybridoma (KN6) derived from adult thymocytes has been analyzed in detail. The molecule recognized by the KN6 gammadelta T-cell receptor is expressed on syngeneic cells of various sources (peritoneal macrophages, thymocytes, spleen cells, and Abelson murine leukemia virus-transformed cell lines) and on transformed cells arrested at an early stage of development (e.g., PCC3 embryonal carcinoma cells). Linkage of the gene coding for the KN6 ligand to the major histocompatibility complex genes could be demonstrated by testing KN6 hybridoma reactivity to cells from congenic strains that differ only at H-2. In addition, analysis of recombinant strains indicates that the gene controlling the KN6 ligand is located in or distal to the TL region. Involvement of the KN6 gammadelta T-cell receptor in this recognition process could be directly demonstrated by transferring the KN6 TL specificity after introduction of the productively rearranged KN6 gamma and delta genes into an alphabeta T-cell clone or into the germ line in transgenic mice. These observations raise the possibility that at least some gammadelta cells regulate hemopoietic cell maturation and activation.

Animals↗
PubMed1989

Different gamma delta T-cell receptors are expressed on thymocytes at different stages of development.

We have analyzed the structural diversity of the murine gamma delta T-cell receptor (TCR) heterodimer expressed on CD4- CD8- thymocyte populations and on TCR gamma delta-expressing hybridomas derived from thymocytes of fetal, newborn, and adult mice. We found that CD4- CD8- thymocytes derived from mice of different pre- and postnatal age preferentially express a gamma delta TCR encoded by different subsets of gamma and delta gene segments. This age-dependent differential expression of gamma delta TCR on thymocytes seems to be accomplished in part by a specific control of rearranged gamma genes operating at the level of transcription and/or RNA stability. We discuss the implications of these findings with respect to the recognition roles of the gamma delta TCR.

Animals↗
PubMed1988

Intestinal intraepithelial lymphocytes are a distinct set of gamma delta T cells.

Lymphocytes are most reliably subdivided on the basis of their receptors for antigen at the cell surface. Three subtypes of lymphocytes are well defined: B cells that bear surface immunoglobulin and make antibody, CD4+T cells with CD3 alpha beta receptors specific for antigen associated with class II major histocompatibility complex molecules, and CD8+T cells with CD3 alpha beta receptors specific for antigen associated with class I MHC molecules. These T cells are responsible for known forms of cell-mediated immunity. The discovery of a third rearranging T-cell specific gene called gamma (refs 1 and 2) has revealed the presence of a new class of T cells bearing a new receptor type, CD3 gamma delta (refs 3-7). To date, neither the function nor the specificity of cells bearing this receptor has been determined. Because gamma delta T cells are the main lymphocyte of epidermis, it was proposed that such cells could be important in surveillance of all epithelia. We have isolated intraepithelial lymphocytes from murine small intestine, and shown that they predominantly or exclusively express CD3 gamma delta receptors. Unlike the epidermal lymphocytes, these cells also express CD8, and they use a different V lambda gene to form their receptor. This strongly suggests that gamma delta T cells home in a very specific manner to epithelia, where they presumably mediate their function.

Animals↗