Biomedical subjects

M H Claesson

Publications and source records attributed to M H Claesson.

At least 37 records · Page 2Linked to original sources

PubMed2000

Cytotoxic T-lymphocyte clones, established by stimulation with the HLA-A2 binding p5365-73 wild type peptide loaded on dendritic cells In vitro, specifically recognize and lyse HLA-A2 tumour cells overexpressing the p53 protein.

Mutations in the tumour suppressor gene p53 are among the most frequent genetic alterations in human malignancies, often associated with an accumulation of the p53 protein in the cytoplasm. We have generated a number of cytotoxic T lymphocyte (CTL) clones that specifically recognize the HLA-A*0201 p53 wild type peptide RMPEAAPPV [65-73], designated R9V, by the in vitro stimulation of CD8 enriched peripheral blood lymphocytes from a healthy HLA-A*0201 donor using peptide loaded autologous dendritic cells. A total of 22 CTL clones were generated from the same bulk culture and demonstrated to carry identical T-cell receptors. The CTL clone, 2D9, was shown to specifically lyse the HLA-A*0201+ squamous carcinoma cell line SCC9 and the breast cancer cell line MDA-MB-468. Our data demonstrate that human peripheral blood lymphocytes from normal healthy individuals comprise T cells capable of recognizing p53 derived wild type (self) peptides. Furthermore, the capacity of R9V specific T cell clones to exert HLA restricted cytotoxicity, argues that the R9V peptide is naturally presented on certain cancer cells. This supports the view that p53 derived wild type peptides might serve as candidate target antigens for the immunotherapeutic treatment of cancer.

Cell Line, Transformed↗

PubMed2000

Deficiency of the intestinal growth factor, glucagon-like peptide 2, in the colon of SCID mice with inflammatory bowel disease induced by transplantation of CD4+ T cells.

BACKGROUND: Glucagon-like peptide 2 (GLP-2) is produced in endocrine L-cells of the intestinal mucosa. Recently, GLP-2 was found to stimulate intestinal mucosal growth. Our objective was to study the content of GLP-2 in the large intestine in a murine model of T-cell-induced inflammatory bowel disease. METHODS: Inflammation was induced by adoptive transfer of CD4+ blast T cells from BALB/c mice to SCID mice. The amount of GLP-2 (1-33) was measured with a specific, NH2-terminally directed radioimmunoassay in tissue extracts from the large intestine of transplanted mice developing colitis and from BALB/c and SCID control mice. RESULTS: In the middle and descending colon segments showing the most severe signs of inflammatory lesions in the CD4+ T-cell-transplanted mice, the amount of GLP-2 was significantly lower than in similar colon segments in both untransplanted SCID mice and normal BALB/c mice (P = 0.0013 and 0.0033). In the descending colon the amount of GLP-2 was 6.7 +/- 1.0 pmol/g protein in the CD4+ transplanted mice compared with 68.4 +/- 20.3 and 42.7 +/- 4.3 in the two groups of control mice. Similar findings were made with regard to the contents of the two other proglucagon-derived intestinal peptides, glicentin and GLP-1. CONCLUSION: The amount of GLP-2 is markedly reduced in the colon of mice with a T-cell-induced inflammatory bowel disease histopathologically resembling both Crohn disease and ulcerative colitis. This observation may provide a pathophysiologic rationale for administration of GLP-2 as a trophic factor in inflammatory bowel disease.

Animals↗

PubMed2000

Identifying cytotoxic T cell epitopes from genomic and proteomic information: "The human MHC project.".

Complete genomes of many species including pathogenic microorganisms are rapidly becoming available and with them the encoded proteins, or proteomes. Proteomes are extremely diverse and constitute unique imprints of the originating organisms allowing positive identification and accurate discrimination, even at the peptide level. It is not surprising that peptides are key targets of the immune system. It follows that proteomes can be translated into immunogens once it is known how the immune system generates and handles peptides. Recent advances have identified many of the basic principles involved. The single most selective event is that of peptide binding to MHC, making it particularly important to establish accurate descriptions and predictions of peptide binding for the most common MHC variants. These predictions should be integrated with those of other steps involved in antigen processing, as these become available. The ability to translate the accumulating primary sequence databases in terms of immune recognition should enable scientists and clinicians to analyze any protein of interest for the presence of potentially immunogenic epitopes. The computational tools to scan entire proteomes should also be developed, as this would enable a rational approach to vaccine development and immunotherapy. Thus, candidate vaccine epitopes might be predicted from the various microbial genome projects, tumor vaccine candidates from mRNA expression profiling of tumors ("transcriptomes") and auto-antigens from the human genome.

Antigen Presentation↗

PubMed1999

MHC-I-induced apoptosis in human B-lymphoma cells is dependent on protein tyrosine and serine/threonine kinases.

In addition to providing the framework for peptide presentation, major histocompatibility complex class I (MHC-I) molecules can act as signal transducing molecules in lymphoid cells. Here we show that the mobilization of intracellular calcium, which follows crosslinking of MHC-I molecules on human B lymphoma cells, is dependent on protein tyrosine kinases and the phosphatidylinositol 3 (PI-3) kinase. Functional studies showed that MHC-I crosslinking induced almost complete inhibition of the spontaneous proliferation of the B lymphoma cells as early as 6 h post-crosslinking and apoptosis 24 h post-crosslinking. Preincubation with either protein tyrosine kinase or protein serine/threonine kinase inhibitors reduced the MHC-I-induced apoptosis to background levels, whereas inhibition of PI-3 kinase had no effect. These data demonstrate a pivotal role for protein tyrosine and serine/threonine kinases in MHC-I-mediated apoptosis in human B-cells and suggest the presence of several MHC-I signaling pathways leading to diverse effects in these cells.

Androstadienes↗

PubMed1999

Human p53(264-272) HLA-A2 binding peptide is an immunodominant epitope in DNA-immunized HLA-A2 transgenic mice.

C57BL/10 mice transgenic for HLA-A2 were immunized with either a full-length DNA-construct of the tumor suppressor p53 or with a minigene encoding the p53-derived immunodominant peptide p53(264)LLGRNSFEV272 (L9V). Vaccination with the full-length p53 construct induced potent cytotoxic activity of splenocytes against L9V-pulsed target cells after in vivo re-stimulation. Vaccination with the L9V-encoding minigene likewise induced specific anti-L9V cytotoxicity in vitro. Subsequent experiments revealed that peptide-pulsed dendritic cells were the most efficient cell types for in vitro re-stimulation. In concordance with this, immunization with L9V-pulsed dendritic cells also induced a potent and specific anti-L9V cytotoxic response in vitro. These data show that HLA-A2/peptide-specific cytotoxic immunity can be generated in vivo against the same immunodominant epitope by immunizing either with full-length DNA or with a DNA minigene encoding the immunodominant peptide epitope.

Animals↗

PubMed1999

Colitis-inducing potency of CD4+ T cells in immunodeficient, adoptive hosts depends on their state of activation, IL-12 responsiveness, and CD45RB surface phenotype.

We studied the induction, severity and rate of progression of inflammatory bowel disease (IBD) induced in SCID mice by the adoptive transfer of low numbers of the following purified BALB/c CD4+ T cell subsets: 1) unfractionated, peripheral, small (resting), or large (activated) CD4+ T cells; 2) fractionated, peripheral, small, or large, CD45RBhigh or CD45RBlow CD4+ T cells; and 3) peripheral IL-12-unresponsive CD4+ T cells from STAT-4-deficient mice. The adoptive transfer into SCID host of comparable numbers of CD4+ T cells was used to assess the colitis-inducing potency of these subsets. Small CD45RBhigh CD4+ T lymphocytes and activated CD4+ T blasts induced early (6-12 wk posttransfer) and severe disease, while small resting and unfractionated CD4+ T cells or CD45RBlow T lymphocytes induced a late-onset disease 12-16 wk posttransfer. SCID mice transplanted with STAT-4-/- CD4+ T cells showed a late-onset IBD manifest > 20 wk posttransfer. In SCID mice with IBD transplanted with IL-12-responsive CD4+ T cells, the colonic lamina propria CD4+ T cells showed a mucosa-seeking memory/effector CD45RBlow Th1 phenotype abundantly producing IFN-gamma and TNF-alpha. In SCID mice transplanted with IL-12-unresponsive STAT-4-/- CD4+ T cells, the colonic lamina propria, mesenteric lymph node, and splenic CD4+ T cells produced very little IFN-gamma but abundant levels of TNF-alpha. The histopathologic appearance of colitis in all transplanted SCID mice was similar. These data indicate that CD45RBhigh and CD45RBlow, IL-12-responsive and IL-12-unresponsive CD4+ T lymphocytes and lymphoblasts have IBD-inducing potential though of varying potency.

Adoptive Transfer↗

PubMed1999

Tumour necrosis factor-alpha (TNF-alpha) transcription and translation in the CD4+ T cell-transplanted scid mouse model of colitis.

The adoptive transfer of activated CD4+ alpha/beta T cell blasts from the spleens of immunocompetent C.B-17+/+ or BALB/cdm2 mice into C.B-17scid/scid (scid) mice induces a colitis in the scid recipient within 8 weeks, which progresses to severe disease within 16 weeks. T cells isolated from recipient colon show a Th1 cytokine phenotype. We have examined the relationship between the phenotype of the cellular infiltrate and the transcription and translation of the proinflammatory cytokine TNF-alpha. The techniques of double indirect immunohistology and in situ hybridization using digoxigenin-labelled riboprobes were used. The prominent myeloid cell infiltrate in diseased tissues comprised F4/80+, Mac-l+ macrophages, neutrophils, dendritic cells and activated macrophages. TNF-alpha transcription and translation were associated with activated macrophages in the lamina propria. Activated macrophages transcribing and translating TNF-alpha were clustered in areas of tissue destruction. Crypt epithelium of inflamed tissues transcribed TNF-alpha at a very early stage of the disease process, but translation of TNF-alpha protein could only be found in advanced epithelial dysplasia. This indicates differential post-transcriptional control of TNF-alpha in activated macrophages and the epithelium.

Adoptive Transfer↗

PubMed1999

In vitro activated CD4+ T cells from interferon-gamma (IFN-gamma)-deficient mice induce intestinal inflammation in immunodeficient hosts.

To investigate the role of IFN-gamma in the immunopathogenesis of inflammatory bowel disease (IBD), severe combined immunodeficient (SCID) mice were transplanted with in vitro activated CD4+ T cells from either wild-type (WT) or IFN-gamma-deficient (IFN-gammaKO) BALB/c mice. In vitro, the two types of T cells displayed comparable proliferation rates and production of tumour necrosis factor-alpha (TNF-alpha), IL-2, IL-4 and IL-10 after concanavalin A (Con A) stimulation. When transplanted into SCID mice, WT CD4+ blasts induced a lethal IBD, whereas IFN-gammaKO blasts induced a less severe intestinal inflammation with moderate weight loss. Intracellular cytokine staining of lamina propria lymphocytes (LPL) revealed comparable fractions of CD4+ T cells positive for TNF-alpha, IL-2 and IL-10 in the two groups of transplanted SCID mice, whereas a two-to-three-fold increase in the fraction of IL-4-positive cells was found in IFN-gammaKO-transplanted SCID mice. Flow cytometric analyses showed strong up-regulation of MHC class II expression of colonic epithelial cells of WT-CD4+ T cell-transplanted compared with IFN-gammaKO-transplanted SCID mice. A significantly higher fraction of CD4+ LPL were found to enter the cell cycle, i.e. to incorporate bromo-deoxy-uridine, and to undergo apoptosis in vivo in WT-transplanted compared with IFN-gammaKO-transplanted SCID mice. These data point towards an important role for IFN-gamma in the development of IBD in SCID mice. The inflammation might be initiated and subsequently enhanced by the ability of IFN-gamma to induce de novo MHC class II expression in the colonic epithelium, a change which could lead to increased antigen processing and production of local proinflammatory cytokines, CD4+ T cell turnover and thereby to exaggeration of disease.

Animals↗

PubMed1999

Signal transduction by the major histocompatibility complex class I molecule.

Ligation of cell surface major histocompatibility class I (MHC-I) proteins by antibodies, or by their native counter receptor, the CD8 molecule, mediates transduction of signals into the cells. MHC-I-mediated signaling can lead to both increased and decreased activity of the MHC-I-expressing cell depending on the fine specificity of the anti-MHC-I antibodies, the context of CD8 ligation, the nature and cell cycle state of the MHC-I-expressing cell and the presence or absence of additional cellular or humoral stimulation. This paper reviews the biochemical, physiological and cellular events immediately after and at later intervals following MHC-I ligation. It is hypothesized that MHC-I expression, both ontogenically and in evolution, is driven by a cell-mediated selection pressure advantageous to the MHC-I-expressing cell. Accordingly, in addition to their role in T-cell selection and functioning, MHC-I molecules might be of importance for the maintenance of cellular homeostasis not only within the immune system, but also in the interplay between the immune system and other organ systems.

Animals↗

PubMed1999

MHC class I cross-talk with CD2 and CD28 induces specific intracellular signalling and leads to growth retardation and apoptosis via a p56(lck)-dependent mechanism.

Ligation of the major histocompatibility complex class I molecules (MHC-I) on human T lymphoma cells (Jurkat) initiates p56(lck)-dependent intracellular signalling events (phosphotyrosine kinase activity; [Ca(2+)](i)) and leads to augmented growth inhibition and apoptosis. MHC-I ligation in concert with ligation of CD2 or CD28 augments, changes or modifies the pattern of activation. Ligation of MHC-I and CD2 alone resulted in growth inhibition, whereas CD28 ligation alone had no effect on cell proliferation. Ligation of MHC-I together with CD2 augmented growth inhibition and enhanced the level of apoptosis. In parallel experiments with the p56(lck)-negative Jurkat mutant cell, JCaM1.6, cross-linking neither influenced cell signalling nor cellular growth functions, indicating a cardinal role of the src kinases in signal transduction via MHC-I, CD2 and CD28 molecules. The results presented here provide evidence for the involvement of MHC-I molecules in the modulation of signal transduction via the CD2 and CD28 costimulatory molecules.

Antigens, CD↗

PubMed1998

Activation of Stat-3 is involved in the induction of apoptosis after ligation of major histocompatibility complex class I molecules on human Jurkat T cells.

Activation of Janus tyrosine kinases (Jak) and Signal transducers and activators of transcription (Stat) after ligation of major histocompatibility complex class I (MHC-I) was explored in Jurkat T cells. Cross-linking of MHC-I mediated tyrosine phosphorylation of Tyk2, but not Jak1, Jak2, and Jak3. In addition, the transcription factor Stat-3 was tyrosine phosphorylated in the cytoplasm and subsequently translocated to the cell nucleus. Data obtained by electrophoretic mobility shift assay suggested that the activated Stat-3 protein associates with the human serum-inducible element (hSIE) DNA-probe derived from the interferon-gamma activated site (GAS) in the c-fos promoter, a common DNA sequence for Stat protein binding. An association between hSIE and Stat-3 after MHC-I ligation was directly demonstrated by precipitating Stat-3 from nuclear extracts with biotinylated hSIE probe and avidin-coupled agarose. To investigate the function of the activated Stat-3, Jurkat T cells were transiently transfected with a Stat-3 isoform lacking the transactivating domain. This dominant-negative acting Stat-3 isoform significantly inhibited apoptosis induced by ligation of MHC-I. In conclusion, our data suggest the involvement of the Jak/Stat signal pathway in MHC-I-induced signal transduction in T cells.

Antibodies, Monoclonal↗

PubMed1998

Protein tyrosine kinases p53/56lyn and p72syk in MHC class I-mediated signal transduction in B lymphoma cells.

Crosslinking of major histocompatibility complex class I (MHC-I) molecules on the surface of human B lymphoma cells was shown to induce protein tyrosine phosphorylation and mobilization of intracellular free calcium. Immunoprecipitations indicated that the protein tyrosine kinases p53/56lyn and p72syk are among the tyrosine-phosphorylated proteins. The kinetics of phosphorylation of these kinases after MHC-I crosslinking differ from the kinetics observed after crosslinking of the B cell antigen receptor (BCR). Additional experiments were performed with chicken lyn- and syk-negative DT40 B cells and the results indicate that these two kinases have different substrate specificity and regulate intracellular free calcium differently in response to MHC-I crosslinking. In addition MHC-I crosslinking of a sIgM-negative DT40 chicken B cell variant results in less activity of tyrosine kinases and less mobilization of intracellular free calcium compared with MHC-I crosslinking of wild-type DT40 cells. Thus, expression of BCR at the cell surface is likely to be important for the signal cascade initiated by MHC-I crosslinking. Our data suggest that signal transduction initiated through ligation of the MHC-I molecule plays a role in the regulation of B cell homeostasis.

Animals↗

PubMed1998

Increased intracellular Th1 cytokines in scid mice with inflammatory bowel disease.

Severe combined immunodeficient (scid) mice engrafted with small pieces of full thickness gut wall from immunocompetent syngenic donors develop a chronic and lethal colitis. Lymphocytes from the lamina propria of engrafted mice were analyzed for phorbol ester/ionomycin-induced cytokine production by intracellular staining. A 4-5-fold increase in the fraction of IFN-gamma-producing CD4+ lamina propria T cells was found in moderately and severely diseased mice when compared to healthy congenic C.B-17 control mice. The number of IL-2-producing T cells was increased by approximately 2-fold when comparing mice suffering from severe disease to healthy control mice. The fraction of TNF-alpha positive CD4+ T cells was increased by a factor of two in both moderately and severely diseased mice. When analyzing Th2 cytokines, it was found that the levels of IL-4-producing CD4+ T cells was not altered in diseased animals, whereas the fraction IL-10-producing CD4+ T cells was reduced by a factor of 20. The combined data showed a 15-25-fold increase in the Th1/Th2 ratio of diseased mice when compared to healthy control mice. No intracellular cytokines could be detected in lymphocytes not treated with phorbol ester/ionomycin. The present data identify a prominent role for Th1-type T helper cells in the immunopathogenesis of gut wall graft-induced inflammatory bowel disease in scid mice.

Animals↗

PubMed1998

Proliferation and apoptosis of lamina propria CD4+ T cells from scid mice with inflammatory bowel disease.

Scid mice transplanted with low numbers of syngeneic CD4+ T cells, develop a chronic and lethal inflammatory bowel disease (IBD) within 4-6 months. We have used in vivo 5-bromo2-deoxy-uridine (BrdU) labeling to assess the proliferation of lamina propria-derived CD4+ T cells in diseased scid mice. The hourly rate of renewal of colonic lamina propria CD4+ T cells in diseased mice was 7% compared with 1.5% in normal BALB/c control mice. Transplantation of scid mice with in vitro activated CD4+ T cells accelerated the disease onset and development in a cell dose-dependent fashion when compared with non-activated CD4+ T cells. In pulse-chase experiments it was shown that BrdU-labeled cells disappeared rapidly from the lamina propria of diseased mice. DNA analysis revealed that this was due to the presence of nearly four times as many apoptotic CD4+ T cells in diseased than in control mice. Further analyses showed that the apoptotic lamina propria CD4+ T cells were derived from cells having entered the cell cycle within the previous 8 h. These data clearly demonstrate that vigorous CD4+ T cell proliferation and death are involved throughout the course of IBD.

Animals↗

PubMed1998

Splenic T helper cell type 1 cytokine profile and extramedullary haematopoiesis in severe combined immunodeficient (scid) mice with inflammatory bowel disease (IBD).

Scid mice develop a severe, chronic, and lethal IBD 3-6 months after engraftment of gut wall from immunocompetent congenic donors, induced by donor-derived CD4+ T cells migrating from the graft. We have investigated intracellular T-helper type 1 (Th1) cytokines in the spleens of gut wall-transplanted scid mice with IBD. Increased fractions of interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) and IL-2-positive CD4+ T cells were found in the spleens of diseased mice compared with control mice. Moreover, a small but significant population of CD4+ T cells which stained positive for granulocyte-macrophage colony-stimulating factor (GM-CSF) was found in scid mice with IBD but was virtually absent in congenic non-scid control mice. Cloning of granulocyte/ macrophage colony-forming cells (G/M-CFC) revealed that both non-transplanted scid mice and scid mice with IBD had an 8-14-fold increase in splenic G/M-CFC compared with control mice. No significant difference in the number of G/M-CFC per total spleen was found between non-transplanted and disease scid mice, although both groups of mice showed a nearly two-fold increase compared with control mice. G/M-CFC were never found in the thymus, liver or lymph nodes of diseased mice. Immunohistochemistry revealed that the multinucleated giant cells observed in the gut wall of diseased mice did not represent haematopoietic foci, but were derived from macrophages. These observations point towards a dominant role for Th1-type CD4+ T cells in the immunopathogenesis of IBD, whereas haematopoiesis does not seem to be affected by the development of the disease.

Animals↗

PubMed1998

Accumulation of immunoglobulin-containing cells in the gut mucosa and presence of faecal immunoglobulin in severe combined immunodeficient (scid) mice with T cell-induced inflammatory bowel disease (IBD).

Scid mice transplanted either with a gut wall graft or with low numbers of purified CD4+ T cells from immunocompetent syngeneic donor mice show clinical signs of IBD 3-4 months post-transplantation. The disease is mediated by mucosa-infiltrating CD4+ TCR alphabeta+ T cells. The pathology of 52 individual colon segments obtained from 20 gut wall- or CD4+ T cell-transplanted diseased scid mice was evaluated by histology and the numbers of infiltrating immunoglobulin-containing cells were determined. In particular, cells positive for IgM, IgA and non-inflammatory immunoglobulin isotypes such as IgG1 and IgG2b were found to accumulate in colon segments displaying the most severe histopathology, including inflammatory cellular infiltration, epithelial hyperplasia and ulcerative lesions. Compared with colon segments of normal C.B-17 mice, the lesional scid colon shows increased levels of cells positive for the IgG classes. Faecal extracts of the CD4+ T cell-transplanted scid mice revealed the presence of all six murine immunoglobulin isotypes. Disease progression was accompanied by an increased level of excreted IgM and IgG3 and decreased levels of IgA. It is concluded that locally secreted immunoglobulins may play an immunomodulating role in the pathological changes observed in the present model of T cell-induced inflammatory bowel disease.

Animals↗

PubMed1998

C1-esterase inhibitor blocks T lymphocyte proliferation and cytotoxic T lymphocyte generation in vitro.

We have previously shown that activated C1s complement and activated T cells cleave beta2-microglobulin (beta2m) in vitro leading to the formation of desLys58 beta2m. This process can specifically be inhibited by C1-esterase inhibitor (C1-inh). Furthermore we showed that exogenously added desLys58 beta2m in nanomolar amounts to a one-way allogenic mixed lymphocyte culture (MLC) increased the endogenous production of IL-2 and the generation of allo-specific cytotoxic T lymphocytes. C1-inh was purified from fresh human plasma and added to human or murine MLC and mitogen-stimulated lymphocyte cultures grown in the presence of complement-inactivated serum. Read-outs were cell proliferation, lymphokine production and development of T cell-mediated cytotoxicity. We found that addition of C1-inh to MLC and mitogen-exposed murine and human lymphocyte cultures inhibited proliferation, the development of allospecific cytotoxic activity, and changed the endogenous production of IL-2, IL-4, IL-10, IL-12 and IFN-gamma. These data clearly demonstrate a regulatory function of C1-inh on T cell-mediated immune functions.

Animals↗

PubMed1998

Veto cell suppression mechanisms in the prevention of allograft rejection.

Substantial evidence has accumulated to suggest that in the near future implementation of the veto-cell-suppressor concept in the treatment of kidney allograft recipients might lead to the establishment of life-long specific allograft tolerance in the absence of further immunosuppressive therapy. Veto suppression prevents the generation of antigen-specific T-helper and cytotoxic T lymphocytes in vitro provided that the T-lymphocyte precursors specifically recognize antigenic peptides associated with the major histocompatibility complex molecules class II and class I, respectively, expressed on the surface of the veto-active cell. Data from a large number of experimental and clinical studies strongly indicate that veto-active cells function in vivo and are capable of preventing allograft rejection. Thus, donor-cell-mediated veto activity is the most likely explanation for the well-known graft tolerizing effect of pretransplant donor blood transfusions in kidney graft recipients. A prerequisite for a veto-active environment in vivo is the establishment of lymphoid microchimerism, in which veto-active donor and recipient cells mutually downregulate potential alloaggression.

Animals↗