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M H Claesson

Publications and source records attributed to M H Claesson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Ligation of major histocompatability complex (MHC) class I molecules on human T cells induces cell death through PI-3 kinase-induced c-Jun NH2-terminal kinase activity: a novel apoptotic pathway distinct from Fas-induced apoptosis.

Ligation of major histocompatability complex class I (MHC-I) molecules expressed on T cells leads to both growth arrest and apoptosis. The aim of the current study was to investigate the intracellular signal pathways that mediate these effects. MHC-I ligation of human Jurkat T cells induced a morphologically distinct form of apoptosis within 6 h. A specific caspase inhibitor, which inhibited Fas-induced apoptosis, did not affect apoptosis induced by MHC-I ligation. Furthermore, MHC-I-induced apoptosis did not involve cleavage and activation of the poly(ADP- ribose) polymerase (PARP) endonuclease or degradation of genomic DNA into the typical fragmentation ladder, both prominent events of Fas-induced apoptosis. These results suggest that MHC-I ligation of Jurkat T cells induce apoptosis through a signal pathway distinct from the Fas molecule. In our search for other signal pathways leading to apoptosis, we found that the regulatory 85-kD subunit of the phosphoinositide-3 kinase (PI-3) kinase was tyrosine phosphorylated after ligation of MHC-I and the PI-3 kinase inhibitor wortmannin selectively blocked MHC-I-, but not Fas-induced, apoptosis. As the c-Jun NH2-terminal kinase (JNK) can be activated by PI-3 kinase activity, and has been shown to be involved in apoptosis of lymphocytes, we examined JNK activation after MHC-I ligation. Strong JNK activity was observed after MHC-I ligation and the activity was completely blocked by wortmannin. Inhibition of JNK activity, by transfecting cells with a dominant-negative JNKK- MKK4 construct, led to a strong reduction of apoptosis after MHC-I ligation. These results suggest a critical engagement of PI-3 kinase-induced JNK activity in apoptosis induced by MHC-I ligation.

Androstadienes↗
PubMed1997

MHC class I ligation of human T cells activates the ZAP70 and p56lck tyrosine kinases, leads to an alternative phenotype of the TCR/CD3 zeta-chain, and induces apoptosis.

Cross-linking of MHC class I (MHC-I) molecules on human T cells induces signal-transduction events, including activation of tyrosine kinases, tyrosine phosphorylation of phospholipase C-gamma 1, and elevation of the intracellular free calcium concentration. In this study, we demonstrate that the ZAP70 tyrosine kinase is tyrosine phosphorylated in Jurkat T cells and in purified peripheral T cells after MHC-I ligation. The tyrosine-phosphorylated ZAP70 kinase exhibits a particular phenotype with low affinities for proteins at 21, 40, 60, and 120 kDa, proteins normally co-precipitated with ZAP70 after TCR/CD3 stimulation. The phosphorylation of ZAP70 after MHC-I ligation was dependent on TCR/CD3 surface expression. One of the natural substrates for ZAP70 is the zeta-chain dimer of the TCR/CD3 complex. MHC-I cross-linking induces a phosphorylated zeta-protein that migrates as a dimer at 42 kDa in SDS-PAGE and differs from the 38-kDa phosphorylated zeta-protein dimer induced by TCR/CD3 cross-linking. Furthermore, we demonstrate that the p56lck tyrosine kinase is tyrosine phosphorylated following MHC-I ligation, and that a p56lck-negative Jurkat T cell mutant does not induce phosphorylation of the zeta-chain and the ZAP70 kinase following MHC-I ligation. Previous studies have demonstrated that lack or diminished activation of ZAP70 is involved in the induction of anergy or apoptosis in T cells. Likewise, MHC-I cross-linking of Jurkat T cells results in growth arrest and induction of apoptosis that is strongly inhibited by herbimycin A, suggesting an essential role of tyrosine kinase activity in the process leading to apoptosis.

Antibodies, Monoclonal↗
PubMed1997

T-cell transfer and cytokine/TCR gene deletion models in the study of inflammatory bowel disease.

Until recently there existed no appropriate immunological animal models for human inflammatory bowel diseases (IBD). Today a number of models, mostly in the mouse and rat, have proved useful in the study of several aspects of IBD, including the histopathology and the disease-inductive and -protective cell types, subsets and cytokines, for example CD4+ T cells, IFN gamma, IL-12, IL-2, IL-10 and TGF beta. Furthermore, these recent IBD models make it possible to examine various chemo- and immunotherapeutic approaches. This review focuses on IBD development in adoptive T-cell transfer models and in gene-deleted mice.

Animals↗
PubMed1996

Spontaneous human squamous cell carcinomas are killed by a human cytotoxic T lymphocyte clone recognizing a wild-type p53-derived peptide.

A cytotoxic T lymphocyte (CTL) clone generated in vitro from the peripheral blood of a healthy HLA-A2-positive individual against a synthetic p53 protein-derived wild-type peptide (L9V) was shown to kill squamous carcinoma cell lines derived from two head and neck carcinomas, which expressed mutant p53 genes, in a L9V/HLA-A2 specific and restricted fashion. Thus, the normal tolerance against endogenously processed p53 protein-derived self-epitopes can be broken by peptide-specific in vitro priming. p53 protein-derived wild-type peptides might thus represent tumor associated target molecules for immunotherapeutical approaches.

Carcinoma, Squamous Cell↗
PubMed1996

MHC class I is functionally associated with antigen receptors in human T and B lymphomas.

We have studied the antibody-induced effect of cross-linking the major histocompatibility complex class I (MHC-I) in human T leukemic cells (Jurkat) and human B lymphoma cells (Solubo, Burkitts lymphoma) on intracellular [Ca2+]i levels. The increase in [Ca2+]i after MHC-I cross-linking in Jurkat cells and Solubo cells was dependent on both intra- and extracellular Ca2+ stores. The initial increase was dependent on intracellular stores but the long-term elevated [Ca2+]i level was due to an influx of Ca2+. The kinetics of Ca2+ release and influx was different in the two cell lines. In both cell lines the increase in [Ca2+]i after MHC-I cross-linking caused upregulation of CD69, an early marker of activation. When studying the effect of MHC-I cross-linking on the TCR- and B cell antigen receptor (BCR)- mediated increase in [Ca2+]i, respectively, we observed that MHC-I had a costimulatory effect on the TCR-mediated increase in [Ca2+]i in Jurkat cells but not on the anti-IgM-mediated activity of Solubo cells. Studies of subpopulations of Jurkat and Solubo cells expressing different levels of MHC-I on their cell surfaces revealed that the TCR- and BCR-mediated increases in [Ca2+]i, respectively, were positively correlated with the level of MHC-I expressed on the cell surface. These observations suggest two different roles in signal transduction for the MHC-I molecules in the T and B cells studied. First, by themselves MHC-I complexes are able to induce activation of intracellular second messenger systems following cross-linking. Second, threshold levels for activation through antigen receptors in T and B cells are dependent on or determined by the actual numbers of MHC-I complexes present in the cell membrane. Thus the present data strongly point to a new, physiological role for MHC-I molecules in T and B cells.

Antigens, CD↗
PubMed1996

Ligation of MHC class I molecules on peripheral blood T lymphocytes induces new phenotypes and functions.

Microgram concentrations of immobilized anti-MHC class I (MHC-I) Ab induced proliferation of resting CD3+ T cells from peripheral blood. In contrast, soluble Ab did not activate T cells. Exposure of T cells to immobilized anti-MHC-I Ab for only 24 h was followed by proliferation and development of T cell-mediated cytotoxicity. Immediately following MHC-I ligation, the T cells responded with increased protein tyrosine phosphorylation, with new bands appearing in the SDS-PAGE. Exposure of T cells to immobilized anti-MHC-I Ab for 24 h induced an increased surface expression of the TCR/CD3 and CD28 molecules. MHC-I-induced proliferation of purified T cells was dependent on cellular interactions with non-T cells. Under certain conditions, in which MHC-I was ligated by picogram concentrations of immobilized anti-MHC-I Ab, anti-TCR/CD3 Ab-induced proliferation of T cells was strongly inhibited. These data clearly demonstrate that ligation of the MHC-I complex on T cells may induce both positive and negative signals. Since the physiologic ligands for MHC-I molecules are TCR and the CD8 molecules, our data may suggest that MHC-I molecules are instrumental in cellular interactions between T cells.

Antibodies, Monoclonal↗
PubMed1996

Immunotoxicity of the pyrethroid insecticides deltametrin and alpha-cypermetrin.

The synthetic pyrethroids deltametrin and alpha-cypermetrin were studied for effects on the immune system in 28-day studies in F344 male rats. Sixteen rats per group were dosed with either deltametrin 0, 1, 5, or 10 mg/kg body wt./day or alpha-cypermertin 0, 4, 8, or 12 mg/kg body wt./day in soy bean oil by gavage. Haematology, bone marrow cell counts, tests for natural killer (NK) cell activity and mitogen response (Con A and STM) as well as quantitation of lymphocyte subpopulations were performed. Spleen cells from immunized animals (six animals/group) were tested for antibody production (SRBC-PFC). Volumes of lymphoid compartments of mesenteric lymph nodes and thymus were estimated using stereological methods. In the deltametrin study an effect was found in the groups receiving 5 or 10 mg/kg body wt. The effects were: increased weight of mesenterial lymph nodes, decreased thymus weight in immunized animals and an increase in numbers of SRBC-PFC and splenic NK cell activity. An effect on relative adrenal weight was seen in the 10 mg/kg body wt. group. No severe effects on the immune system was found. The lowest effect level of alpha-cypermetrin was 12 mg/kg body wt./day based on increased relative adrenal weight.

Adrenal Glands↗
PubMed1996

Cytotoxic reactivity of gut lamina propria CD4+ alpha beta T cells in SCID mice with colitis.

Polyclonal, mucosa-seeking memory/effector CD4+ T cells containing a large fraction of blasts activated in situ accumulate in the gut lamina propria of severe-combined immunodeficient (SCID) mice developing colitis after CD4+ T cell transplantation. CD4+ T cells isolated from different repopulated lymphoid tissues of transplanted SCID mice proliferate in vitro in the presence of interleukin (IL)-2 + IL-7. CD3 ligation enhances this cytokine-supported proliferation in CD4+ T cells from the spleen and the mesenteric lymph node of transplanted SCID mice; CD3 ligation suppresses the cytokine-supported proliferation in CD4+ T cells from the gut lamina propria in a cell density- and dose-dependent manner. Almost all CD4+ T cells from repopulated lymphoid tissues of transplanted SCID mice express CD95 (Fas) on the cell surface, and a large fraction of CD4+ T cells from the gut lamina propria of transplanted SCID mice express the Fas ligand on the surface. Gut lamina propria CD4+ T cells show Fas-dependent cytotoxicity. A large fraction of gut lamina propria CD4+ T cells that infiltrate the inflamed colon in transplanted SCID mice are activated in situ and many CD4+ T cells are apoptotic. Hence, a large fraction of colitis-inducing CD4+ T cells undergo activation-induced cell death in situ and can damage other cells through Fas-dependent cytotoxicity.

Animals↗
PubMed1996

CD4+ T lymphocytes injected into severe combined immunodeficient (SCID) mice lead to an inflammatory and lethal bowel disease.

Transfer of 2 x 10(5) congenic or semiallogenic purified TCR alphabeta+ CD4+ T cells to SCID mice leads to an infiltration of the recipient gut lamina propria and epithelium with a donor-derived CD4+ T cell subset which induces a lethal inflammatory bowel disease (IBD) in the recipients. In contrast, IBD was not observed in SCID mice transplanted with unfractionated splenic cells. The earliest detectable pathological changes after CD4+ T cell transfer were proliferation and hypertrophy of the entire colonic epithelial layer, including increased mitotic activity, increased expression of epithelial nuclear proliferation antigen, and elongation of the crypts. Later on, massive mononuclear cell infiltration, hypertrophy of all layers of the colon and occasional epithelial ulcerations were observed. At this stage, accumulations of IgA, IgM and small numbers of IgG1-, IgG2- and IgG3-secreting plasma cells were present in the lamina propria of both the small and large intestine. We conclude that low numbers of intraveneously transferred CD4+ T cells induce IBD in SCID mice. In the late stages of CD4+ T cell-induced IBD, the colonic lamina propria becomes infiltrated with macrophages, neutrophils and plasma cells secreting IgA, IgM, and to a lesser degree IgG antibodies which might play an accessory role in the pathogenesis of IBD.

Adoptive Transfer↗
PubMed1996

MHC class I phenotype and function of human beta 2-microglobulin transgenic murine lymphocytes.

Lymphoid cells from beta 2-microglobulin (beta 2m) knockout mice transgenic for human (h) beta 2m (C57BL/10 m beta 2m-/h beta 2m+) were compared with normal mice for their binding to exogenously added h beta 2m, binding to a H-2Db peptide and for functional activity in a one-way allogenic MLC. Based on data from cellular binding studies, Scatchard analyses and flow cytometry, it is concluded that exogenous h beta 2m does not bind to hybrid MHC class I (MHC-I) molecules composed of mouse heavy chain/h beta 2m molecules expressed on lymphocytes of transgenic mice. Immunoprecipitation and SDS-PAGE analysis of metabolically labelled normal C57BL/6 lymph node cells showed binding of exogenous h beta 2m to MHC-I, in particular, to the H-2Db molecule through an exchange with endogenous mouse beta 2m. In contrast to normal H-2Db molecules, hybrid H-2Db expressed on the surface of transgenic lymphocytes binds radiolabelled peptide in the absence of exogenous added h beta 2m suggesting that a stable fraction of hybrid H-2Db molecules is empty or contain peptides with very low affinity. In a one-way allogenic mixed lymphocyte culture, transgenic splenocytes were found to be far less stimulatory than normal splenocytes. In contrast, transgenic alloreactive cytotoxic T lymphocytes developed earlier in MLC than their non-transgenic counterparts. These data indicate that the hybrid mouse heavy chain/h beta 2m complex alters the alloantigenic repertoire and influences important aspects of T-cell activation.

Animals↗
PubMed1995

MHC class I signaling in T cells leads to tyrosine kinase activity and PLC-gamma 1 phosphorylation.

We have studied the biochemical signal pathway leading to a rise in intracellular free calcium concentration ([Ca2+]i) following cross-linking of MHC class I (MHC-I) molecules on human T leukemic Jurkat cells. Evidence is presented that MHC-I signaling is dependent on tyrosine kinase activity before the observed increase in [Ca2+]i. Thus, tyrosine phosphorylation was detected within 5 s after MHC-I cross-linking, whereas an increase in [Ca2+]i was observed after a lag period of 30 s. Moreover, an inhibitor of tyrosine kinases, herbimycin A, almost completely blocked MHC-I-induced tyrosine phosphorylation and the subsequent calcium response. The early tyrosine kinase activity was found to be dependent on expression of the TCR/CD3 complex and the CD45 molecule on the surface of the T cells. Furthermore, MHC-I cross-linking was shown to tyrosine phosphorylate PLC-gamma 1 (phospholipase C-gamma 1). Collectively, these results indicate that the MHC-I signaling pathway is linked to activation of tyrosine kinase(s) in Jurkat cells.

Benzoquinones↗
PubMed1995

A gut-homing, oligoclonal CD4+ T cell population in severe-combined immunodeficient mice expressing a rearranged, transgenic class I-restricted alpha beta T cell receptor.

We studied the peripheral T cell compartment of H-2b severe combined immunodeficient (scid) mice that express a transgenic (tg) alpha beta T cell receptor (TcR) specific for the H-Y (male) epitope presented by the H-2 class I Db molecule. Large populations of CD3+ NK1.1-TCR beta T+ T cells were present in spleen, mesenteric lymph nodes, peritoneal cavity, lamina propria and epithelial layer of the small and large intestine of 6- to 10-month-old, male and female tg scid mice. Only low numbers of CD3+ T cells were recovered from inguinal, popliteal, or axillary lymph nodes. We studied CD4+ T cells in these tg scid mice. CD4+ T cells were found in the peritoneal cavity, in the mesenteric lymph nodes and in the intraepithelial layer and lamina propria of the gut. All CD4+ T cells were CD44+ (i.e. showed evidence of antigen-driven differentiation) and expressed the tg V beta 8.2 TcR beta-chain (TcR beta T+). Only few CD4+ T cells expressed the tg V alpha 3+ TcR alpha-chain (TcR alpha T). cDNA was prepared from CD4+ T cells from spleen or mesenteric lymph nodes of individual male and female tg scid mice; sequence analyses of polymerase chain reaction-amplified, endogenous TcR alpha-chain (TcR alpha E) transcripts indicated that > 90% of the TcR alpha E-chain transcripts were in-frame, that the TcR alpha E repertoire in CD4+ T cell populations was oligoclonal, and that the TcR alpha E repertoire was different in individual tg scid mice. Hence, an oligoclonal, leaky CD4+ T cell population is selected in tg scid mice that apparently responds to gut-derived antigens. No inflammatory bowel disease (IBD) was evident in the small or large intestine of 6- to 10-month old tg scid mice. After adoptive transfer of purified CD4+ T cells (10(5) cells per mouse) from tg scid mice into non-tg H-2b scid mice, CD4+ TcR alpha T-beta T+ cells were found in gut tissues of the immunodeficient host. Transplanted scid mice developed clinical and histological signs of IBD. An oligoclonal, gut-homing, memory/effector CD4+ CD44+ TcR beta T+ TcR alpha T-T cell subset from leaky tg scid mice thus has a pathogenic potential when released from the control of TcR beta T+ TcR alpha T+ T cells.

Animals↗
PubMed1995

Tumour-infiltrating lymphocytes mediate lysis of autologous squamous cell carcinomas of the head and neck.

Tumour-infiltrating lymphocytes (TIL) and tumours from six patients with squamous cell carcinomas of the head and neck (SCCHN) were investigated. The six tumours all expressed major histocompatibility complex (MHC) class I antigens both in vivo and as tumor cell lines grown in vitro. In addition, the cancer cells either overexpressed the tumour-suppressor gene product p53 or harboured human papilloma virus 16/18 (HPV). The TIL were expanded in vitro in the presence of interleukin-2, immobilised anti-CD3 mAb and soluble anti-CD28 mAb. Expanded TIL cultures contained both CD4+ and CD8+ T cells, but generally contained few CD56+CD3- cells of the natural killer (NK) phenotype. CD8+ T cells dominated the individual TIL cultures from five of the six patients and showed significant autologous tumour cell lysis. In TIL cultures derived from four of these tumour-reactive TIL cultures, killing could be partially blocked by an anti-MHC class I mAb. TIL cultures reacting with autologous tumour cells also showed strong TCR/CD3-redirected cytotoxicity when assayed against hybridoma cells expressing anti-TCR/CD3 mAb as well as natural-killer(NK)-like activity. A number of TIL cultures devoid of autologous tumour cell lysis were capable of lysing the natural-killer(NK)-sensitive K562 cell line suggesting that the SCCHN cells themselves are resistant to NK-like lysis. In conclusion, TIL cultures from head and neck carcinomas contain T cells which, upon expansion in vitro, can lyse autologous tumour cells in a MHC-class-I-restricted fashion. Thus, the results of the present study document that carcinomas of the head and neck in some patients are infiltrated by cytotoxic T cell precursors potentially capable of rejecting the autologous tumour.

Adult↗
PubMed1995

T cell-mediated cytotoxicity against p53-protein derived peptides in bulk and limiting dilution cultures of healthy donors.

The p53 tumour suppressor gene product plays an important role in the development of most human cancers. Point mutations in the p53 gene are common in malignant states and results in over-expression of wild type and mutant determinants of the p53 protein. This process might generate MHC-I restricted epitopes for T cell recognition and p53-derived peptides have been suggested as targets for tumour-specific cytotoxic T lymphocytes (CTL). Our primary aim was to estimate the frequencies of p53-peptide reactive CTL precursors (CTLp) in peripheral blood from healthy young individuals. We selected wild type and mutated peptides derived from the p53 sequence with a binding motif for HLA-A2.1 molecules. Peripheral blood mononuclear cells (PBMC) from healthy HLA-A2 donors were stimulated in vitro in bulk cultures as well as in limiting dilution cultures using autologous cells pulsed with p53 peptides as stimulator cells. T cell reactivity was observed towards both wild type and mutated p53 peptide epitopes with CTL precursor frequencies varying from 1:2 x 10(4) to 1:1.5 x 10(5). These results might suggest the presence of an ongoing immune response in normal individuals against cells expressing increased levels of p53 protein.

Adult↗
PubMed1994

Gut-homing CD4+ T cell receptor alpha beta+ T cells in the pathogenesis of murine inflammatory bowel disease.

We studied which T cell subsets from the gut-associated lymphoid tissue (GALT) can migrate out of the gut mucosa and repopulate GALT compartments of an immunodeficient (semi)syngeneic host. Many distinct lymphocyte subsets were found in GALT of immunocompetent H-2d (BALB/c, BALB/cdm2, C.B-17+/+) mice. No antigen receptor-expressing lymphoid cells were found in GALT of congenic C.B-17 scid/scid (scid) mice. The heterotopic transplantation of a full-thickness gut wall graft from the ileum or colon of immunocompetent (C.B-17+/+, BALB/cdm2) donor mice onto immunodeficient scid mice selectively reconstituted a CD3+ T cell receptor alpha beta+ CD4+ T cell subset. CD4+ cells of this subset expressed the surface phenotype of mucosa-seeking, memory T cells. In the immunodeficient scid host, this gut-derived CD4+ T cell subset was found in spleen, peritoneal cavity, mesenteric lymph nodes (LN), epithelial layer and lamina propria of the small and large intestine, but not in peripheral LN. Scid mice heterotopically transplanted with gut from a congenic, immunocompetent donor developed clinical and histological signs of inflammatory bowel disease (IBD). Hence, the selective repopulation of GALT compartments with CD4+ T cells from normal GALT plays an essential role in the pathogenesis of IBD in an immunodeficient host.

Animals↗
PubMed1994

In vivo infiltration of mononuclear cells in squamous cell carcinoma of the head and neck correlates with the ability to expand tumour-infiltrating T cells in vitro and with the expression of MHC class I antigens on tumour cells.

A series of 18 head and neck squamous cell carcinoma biopsies, 6 primary and 12 recurrent, were investigated for tumour-infiltrating mononuclear cells with monoclonal or polyclonal antibodies. Our results suggest that the number of T cells at the tumour edge in vivo correlates well with their ability to expand in vitro in the presence of high-dose interleukin-2 (2000 U/ml). High MHC class I antigen expression on tumour cells was found to be positively correlated with p53 overexpression, suggesting that p53-derived peptides, wild-type or mutated ones, presented by MHC class I antigens, are potential targets for MHC-restricted cytotoxic T cells in head and neck squamous cell carcinomas. However, lack of correlation between peritumoural T cell infiltration in vivo and T cell expansion in vitro, on the one hand, and p53 overexpression on tumour cells, on the other hand, suggests absence of p53-peptide-specific T cells in the patients. Eight out of ten expanded tumour-infiltrating lymphocyte (TIL) cultures showed T-cell-mediated cytotoxicity. "Promiscuous" cytotoxic T cell activity against the natural-killer-cell-sensitive K562 target cell line was observed in three out of ten TIL expansion cultures.

Animals↗