Hiroko Ushio

Supernormal Histamine Release and Normal Cytotoxic Activity of Beige (Chédiak-Higashi Syndrome) Rat Mast Cells with Giant Granules

The beige rat is an animal model of the Chédiak-Higashi syndrome. Since mast cells can be easily purified from the peritoneal cavity of rats, we investigated the function of beige rat mast cells with giant granules by using quantitative methods. Beige and normal rat mast cells were sensitized with anti-dinitrophenol (DNP) IgE antibodies and stimulated by DNP conjugated with human serum albumin. The proportion of histamine released to total histamine was significantly greater in beige rat mast cells than in normal rat mast cells. Since the supernormal histamine release of beige rat mast cells was observed after treatment with 12-O-tetradecanoylphorbol 13-acetate, calcium ionophore A23187, substance P or compound 48/80, it appeared to be attributable to the enlargement in granules in beige rat mast cells. Spontaneous cytotoxic activity of mast cells was assayed by incubating purified mast cells with 51Cr-labelled WEHI-164 cells. Both beige and normal rat mast cells showed significant cytotoxic activity, but no significant difference was detectable between beige and normal rat mast cells. Even after IgE-mediated stimulation, no significant difference in cytotoxic activity was detectable between beige and normal rat mast cells either. Giant granules of beige rat mast cells did not appear to influence the cytotoxic activity of mast cells.

Murine Granulocyte-Macrophage and Mast Cell Colony Formation Promoted by Nerve Growth Factor

The nerve growth factor (NGF) is widely distributed in the target tissues of sympathetic neurons. Hemopoietic organs such as the bone marrow (BM) and spleens are known to be innervated by noradrenergic sympathetic neurons. Some of their constitutive cells express NGF receptors (lymphocytes and stroma cells) and its biologic effects have been extensively studied in the immune system and inflammatory responses. However, the effects of NGF on hemopoiesis have been little examined. Recently, we demonstrated that NGF promoted mast cell colony formation from murine BM cells (BMC) or BMC-derived cultured mast cells and induced the phenotypic changes in standard hemopoietic assays. Besides, we demonstrated NGF-enhanced murine neutrophil survival and functional properties. In this study, in order to investigate NGF activities on neutrophil differentiation, we examined granulocyte-macrophage (GM) colony formation from murine BMC or spleen cells (SC) in the methylcellulose culture. We also assessed mast cell colony formation. GM colonies were counted on day 5 and mast cell colonies were counted on day 20 in culture. Although NGF alone (50 ng/ml) neither supported GM nor mast cell colony formation, addition of various doses of NGF to the suboptimal dose of pokeweed mitogen-stimulated SC-conditioned medium (2.5%) or interleukin 3 (50 U/ml), well-known colony-stimulating factors, increased the number of GM and mast cell colonies from both BMC and SC in a dose-dependent manner. These colony formation-enhancing effects of NGF were inhibited by the addition of neutralizing sheep anti-NGF antibodies. The results suggest that NGF may act to develop granulopoiesis including neutrophil and mast cell differentiation in cooperation with hemopoietic factor(s) during inflammatory processes.

A role for platelet release of serotonin in the initiation of contact sensitivity.

Finding contact sensitivity (CS) responses that were fairly normal in ear swelling, and in serotonin (5-HT) dependence in mast-cell-deficient mice, led to experiments to determine whether platelets supplemented mast cells as a source of 5-HT in CS. Severe depletion of platelets, and consequently blood 5-HT, with antiplatelet antibody, strongly inhibited CS, especially in mast-cell-deficient mice, suggesting that platelets supplemented mast cells. Furthermore, human platelets sensitized in vitro with anti-(tri-nitro-phenyl) IgE, and transferred intravenously together with isolated late-acting effector T cells, provided CS initiation due to local 5-HT release. Similar, IgE-dependent in vitro release of 5-HT was C dependent. These findings establish the importance of antigen-specific platelet release of 5-HT in CS initiation.

Protective immunity and mast cell and eosinophil responses in mice infested with larval Haemaphysalis longicornis ticks

WBB6F1 ‐+‐ /+ mice were infested with larval Haemaphysalis longicornis ticks twice at an interval of 14 days: apparent resistance against ticks was expressed in the second infestation. The first infestation induced degranula‐tion of a small number of mast cells at the feeding sites within 6 days, and resulted in two‐fold increases of mast cell numbers on day 14 with a significant elevation of total immunoglobulin E (IgE) levels in sera and high proportion of IgE‐bound mast cells. The second infestation resulted in the intensive degranulation of the increased mast cells at the feeding sites. Eosinophils infiltrated into the feeding sites of ticks: the second infestation led to a greater maximal level of the infiltrating eosinophils. These data suggest that the resistance against larval H. longicornis ticks in mice may be expressed as a result of immediate hypersensitivity and many eosinophils infiltrating from the blood to the feeding sites might contribute to the tick rejection.