Biomedical subjects

H Hisaeda

Publications and source records attributed to H Hisaeda.

45 records · Page 3Linked to original sources

PubMed1996

Mechanisms of HSP65 expression induced by gamma delta T cells in murine Toxoplasma gondii infection.

We have previously reported that the expression of an endogenous 65-kD heat shock protein (HSP65) in macrophages is closely correlated with the protection against infection by Toxoplasma gondii in mice, and gamma delta T cells play a critical role in the expression of this protein. In this study, we investigated how gamma delta T cells contribute to the protection and HSP65 expression. After intraperitoneal infection with bradyzoites of the Beverley strain of T. gondii, mRNA encoding IFN-gamma and TNF-alpha was detected in the peritoneal gamma delta T cells by RT-PCR technique, and macrophages that produced nitric oxide (NO) and expressed HSP65 were also detected. Depletion of gamma delta T cells resulted in suppression of NO production by macrophages, and it also inhibited HSP65 expression. HSP65 expression, however, does not appear to be induced by stimulation with NO, since treatment with NG-monomethylarginine, an inhibitor of NO synthesis, did not attenuate the expression of HSP65. This expression was completely suppressed when mice were simultaneously treated with anti-IFN-gamma and anti-TNF-alpha although either antibody alone was less effective. The synergistic effect of these cytokines was also demonstrated by an in vitro experiment, in which peritoneal macrophages were cultured with recombinant IFN-gamma and TNF-alpha. These results indicate that gamma delta T cells, which protect against infection with T. gondii induce the expression of HSP65 by secreting IFN-gamma and TNF-alpha and the production of NO, and that the expression of HSP65 is independent of inflammatory chemical compounds like NO and H2O2.

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PubMed1996

Function of CD4 molecules in LEC rat thymocytes.

Long-Evans Cinnamon (LEC) rats show a novel maturational arrest from CD4+8+ to CD4+8- thymocytes but a cause of this mutation is not identified. The candidate for this mutation is a defect in the function of CD4 or major histocompatibility complex (MHC) class II because gene-disrupted mice defective for CD4 or MHC class II molecules show a specific defect in CD4+ T cells. Previously, we showed that MHC class II is not a cause of this maturational arrest. Therefore, in this study, we focus on the function of CD4 molecules in LEC rat thymocytes. CD4 molecules on LEC rat thymocytes associated with protein tyrosine kinase, p56[lck], normally. Furthermore, cross-linking of CF4 molecules by anti-rat CD4 mAb elicited the elevation of intracellular calcium concentrations ([Ca2+]i) in LEC rat thymocytes, suggesting that CD4 molecules can deliver the signal normally. These results indicate that function of CD4 is normal and the maturational blockade of CD4+8- thymocytes in LEC rats is not caused by specific lymphocyte molecules that have been shown in gene-disrupted mice.

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PubMed1995

Gamma delta T cells play an important role in hsp65 expression and in acquiring protective immune responses against infection with Toxoplasma gondii.

Previously, we reported that the expression of hsp65 within and on host macrophages correlates closely with protection against infection with Toxoplasma gondii in mice. Herein, we propose that gamma delta T cells play a crucial role in the induction of hsp65 and also in the protective immune response to T. gondii. Intraperitoneal inoculation with this protozoan resulted in hsp65 being expressed on and in host peritoneal macrophages and resulted in an increase of T cells bearing the gamma delta receptor with Thy-1+ and Thy-1- phenotypes in the peritoneal cavity and spleen. When mice were depleted of gamma delta T cells by the administration of a mAb, hsp65 expression was markedly decreased. In contrast, the expression of this protein was rather enhanced and gamma delta T cells were prominently expanded in mice depleted of alpha beta T cells. The protection in mice treated with the mAb paralleled the magnitude of hsp65 expression. Mice depleted of gamma delta T cells died most frequently in the early stages of infection, whereas most of those depleted of alpha beta T cells survived the early stages of lethal infection with T. gondii. However, the latter group of mice did not definitely control the T. gondii infection in its late stages. IFN-gamma was not essential for either the expression of hsp65 or the resistance induced by gamma delta T cells, as demonstrated in mice treated with mAb to murine IFN-gamma. These findings indicated that gamma delta T cells having both the Thy-1+ and Thy-1- phenotypes contribute to hsp65 expression within and on macrophages in an IFN-gamma-independent manner. This, in turn, plays a role in the development of protective immunity during the early stage of this parasitic infection.

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PubMed1995

Establishment of a xenogeneic chimera without GVHD in NK cell-depleted SCID mice by grafting rat fetal liver cells.

Rat lymphopoiesis did not develop when naive SCID mice were transplanted with rat fetal liver cells. However, when SCID mice were depleted of NK cells by administration of anti-murine IL-2R beta mAb before transplantation, remarkable reconstitution of both rat T and B cells was observed in these mice without any evidence of graft-versus-host disease macroscopically or histologically. T cells in these reconstituted mice proliferated well in response to Con A and third-party rat and mouse antigens, whereas no response was seen to the stimulation with either donor rat- or host mouse-type cells. When these xenogeneic chimera mice had been immunized with SRBC, these mice exhibited DTH reaction and antibody production against the homologous antigen. These results indicate that rat fetal liver cells can differentiate to functional T and B cells in the xenogeneic microenvironment of SCID mice, if host NK cells are depleted beforehand. These rat-type T cells develop within SCID thymuses and acquire tolerance to either donor F344 rat or host SCID mouse antigens.

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PubMed1995

Dissociation between the mitogenic effect and antitumor activity of seed extract from Aeginetia indica L.

The extract from seeds of Aeginetia indica L. (AIL), a parasitic plant, induces potent antitumor immunity against Meth A fibrosarcomas in BALB/c mice. AIL also possesses a thymocyte co-stimulatory effect in vitro with suboptimal dose of Con A, a B cell mitogenic effect, and stimulates AIL-primed CD4+ T cells to produce Th1-type cytokines. In this study, we investigated the relationship between mitogenicity and antitumor activity with AIL. When AIL was analyzed by SDS-PAGE, there was strong and diffuse staining in the region between 14 kDa and the bottom of polyacrylamide gel and it was unaffected when AIL was digested with proteinase K (PK) before SDS-PAGE. Some bands with different molecular mass were also found in silver-stained gel and they disappeared completely by incubating AIL with PK before SDS-PAGE. The in vitro thymocyte co-stimulatory and B cell mitogenic effects were not influenced by digesting AIL with PK but were completely suppressed by the oxidation of AIL with sodium periodate before culture. In contrast, the in vivo antitumor activity was completely abolished by PK, but it was not affected by periodate oxidation. We generated mAbs specific for AIL and investigated the influence on the antitumor activity of AIL in vivo. Around 60-80% of tumor-bearing mice failed to recover from a challenge tumor when they were treated with supernatants isolated from mAb-induced precipitation reactions. Immunoblotting (Western blotting) revealed that all the mAbs reacted exclusively with a 50-60 kDa protein and that this reactivity was not influenced after oxidizing the blots with sodium periodate. We demonstrated that AIL contains polysaccharides and proteins. The polysaccharides induced B cell mitogenic and thymocyte co-stimulatory effects in vitro, while the proteins, especially a 50-60 kDa protein containing non-carbohydrate epitopes recognized by the mAbs, mediated antitumor activity in vivo.

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PubMed1994

Split tolerance between spleen and lymph node cells in severe combined immunodeficiency mice grafted with AKR fetal liver cells.

Severe combined immunodeficient (SCID) mice defective in stem cells for T and B cells appear to be an ideal host for construction of chimeric mice. When bone marrow cells are used as a source of stem cells, however, host SCID mice do not always show sufficient reconstitution. In this study, fetal liver cells from AKR embryos were transplanted into SCID mice without prior irradiation. This treatment induced full reconstitution of lymphopoiesis as evaluated by flow cytometry analysis and serum Ig production 2 months after transplantation. Thus, fetal liver cells seem to be a better source for reconstitution of SCID mice than bone marrow cells. Lymph node (LN) cells of these mice (FLT mice) had no proliferative or cytotoxic activities against either host-type (C.B-17) or donor-type (AKR) spleen cells. However, spleen cells from FLT mice exhibited marked proliferative and cytotoxic activities against C.B-17 cells, with no activities against AKR cells. Split tolerance against C.B-17 cells in spleen and LN cells was not a transient phenomenon, since similar results were obtained from a cytotoxic T lymphocyte assay 4 months later. In spite of the strong host reactivity in vitro, aberration of clonal deletion or development of a graft-versus-host disease was not seen in FLT mice. As IL-2 induced the host reactivity of LN cells in a mixed lymphocyte reaction, potentially host-reactive T cells were present in LN but were rendered anergic. Tolerance in FLT mice seems to be regulated by a peripheral mechanism. We supposed that the split tolerance in FLT mice was induced by the different antigenicity between the spleen and LN.

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PubMed1994

gamma delta T cells play a crucial role in the expression of 65,000 MW heat-shock protein in mice immunized with Toxoplasma antigen.

Toxoplasma gondii is an obligate intracellular protozoan parasite and cellular immunity plays a crucial role in protection against infection with this pathogen. When mice are immunized with Toxoplasma homogenate, they readily acquire resistance against infection with a lethal dose of a low virulence Beverley strain of T. gondii. We have reported previously that expression of 65,000 MW heat-shock protein (hsp 65) in host macrophages closely correlates with protective potentials of hosts, while this protein is not expressed in Toxoplasma themselves. In this study, we examined the mechanism of expression of hsp 65 in mice immunized with Toxoplasma homogenate. Heat-shock protein was detected in peritoneal macrophages of BALB/c mice immunized 7 days previously by electroblot assay with a specific monoclonal antibody (mAb) for microbial hsp 65. Furthermore, an immunogold ultracytochemistry assay demonstrated that this protein was expressed on the cell surface of peritoneal macrophages in immune mice. This expression was not induced in those of immune athymic nude mice and SCID mice. Treatment of BALB/c mice with anti-Thy-1.2 mAb 1 day before immunization led to an almost complete loss of the expression of hsp 65. To determine the subsets of T cells responsible for induction of this protein, mice were depleted of gamma delta T cells, alpha beta T cells, CD4+ T cells or CD8+ T cells by treating with corresponding antibodies before immunization. From these experiments, gamma delta T cells were shown to be essential for the expression of hsp 65, although CD4+ alpha beta T cells also contributed to some extent. Thus, gamma delta T cells appear to play an important role in protective immunity against infection with T. gondii through mediating the expression of hsp 65 in host macrophages.

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PubMed1993

Development of T cells in SCID mice grafted with fetal thymus from AKR mice or F344 rats.

To examine the development of T cells within an allogeneic or xenogeneic environment, we engrafted the fetal thymus from AKR mice or F344 rats under the kidney capsule of SCID mice (mTG and rTG mice). T lymphopoiesis developed in SCID mice 2 months after transplantation, although the ratio of CD4/CD8 in both experimental groups was different from that of normal control. T cells in mTG mice did not show in vitro proliferation or cytotoxicity against either host-type C.B-17 (H-2d) or donor-type AKR (H-2k) cells, while they exerted potent activities against third-party B10 (H-2b) cells. In contrast, T cells in rTG mice exhibited proliferation against both host-type C.B-17 and donor-type F344 rat cells. Consistently, graft-vs.-host disease symptoms developed in these mice and histological examination showed impressive infiltration of lymphocytes into the skin or into the mucosal layers of the stomach. Activated state of T cells in rTG mice was also evidence by the positive expression of interleukin-2 receptor. Taken together, fetal thymus appears to contain progenitor cells which are sufficient for in vivo reconstitution of T lymphopoiesis, but species-specific environment is important for the induction of tolerance. In mTG mice, V beta 6+ T cells reactive to donor Mlsa determinants and V beta 3+ T cells reactive to host Mlsc determinants were deleted, suggesting that tolerance was regulated mainly by clonal deletion. By contrast, V beta 11+ T cells reactive to Mlsf determinants were not deleted possibly due to the lack of their ligands.

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PubMed1992

Induction of heat shock protein closely correlates with protection against Toxoplasma gondii infection.

Heat shock proteins (HSPs) are evolutionarily highly conserved polypeptides that appear to be produced by many cells to preserve cellular functions under a variety of conditions of stress, including infections. We report that a 65-kDa HSP is present in mouse peritoneal cells that have been infected with a low-virulence (Beverley) strain of Toxoplasma gondii, as determined by electroblot assay using a monoclonal antibody specific for microbial HSP65. This HSP is, however, not expressed when infection occurs with the high-virulence RH strain of T. gondii. Furthermore, HSP was demonstrable in mice that acquired resistance against infection with a lethal dose of bradyzoites of the Beverley strain or even of an inoculum of a highly virulent strain of T. gondii (RH). From these results, it can be suggested that HSPs play an important role in developing effective defenses that include effective immune responses against infection with Toxoplasma parasites in vivo.

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