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Tripe palms associated with systemic mastocytosis: the role of transforming growth factor-alpha and efficacy of interferon-alfa.

Tripe palms are thickened, moss-like or velvety textured exaggerations of the normal dermatoglyphics. The disease belongs to the spectrum of papulosquamous paraneoplastic syndromes. Although suspected, the role of transforming growth factor-alpha (TGF-alpha) has not been clearly established. A 54-year-old man with systemic mastocytosis presented with thickening and darkening of the palms and soles. We performed skin biopsies for light microscopy (including toluidine blue), in situ hybridization and double labelling, and determination of serum tryptase, histamine and TGF-alpha levels. Toluidine blue stained the mast cells that had massively infiltrated the dermis. Tripe palm samples showed extensive hyperkeratosis. The TGF-alpha probe reacted strongly with the mast cells that also reacted with the antitryptase monoclonal antibody. Elevated tryptase, histamine and TGF-alpha levels prior to interferon-alfa administration decreased under treatment. The demonstration of TGF-alpha in infiltrating mast cells, the clinical regression of tripe palms and the lowering of the serum level and the mast cell molecular signal of the cytokine when systemic mastocytosis was controlled by interferon-alfa, suggest a key role for TGF-alpha in this cutaneous paraneoplastic syndrome.

Dermatoglyphics↗

Effect of granulocyte macrophage colony-stimulating factor in a patient with benign systemic mastocytosis.

We report the in vitro and in vivo effects of granulocyte macrophage colony stimulating factor (GM-CSF), a known inhibitor of in vitro mast cell differentiation, in a patient with benign, adult-onset systemic mastocytosis. In vitro effects of GM-CSF on bone marrow cultures before the start of treatment showed a marked inhibition of mast cell marker expression [tryptase, Kit, and high-affinity IgE receptor (FcepsilonRIalpha)] at both protein and mRNA levels. Therefore, the patient was treated with daily injections of GM-CSF for 10 weeks. After an initial improvement, increasing worsening of clinical symptoms was noted, and the patient refused further treatment. Lesional skin biopsies showed an increase of toluidine blue-positive mast cells, compared with uninvolved skin, with further significant increase after treatment. Similar results were obtained on staining for mast cell-specific tryptase and Kit, as well as for CD1a and FcepsilonRIalpha. These findings show that GM-CSF inhibits human bone marrow mast cell differentiation in vitro, and also in mastocytosis. However, GM-CSF apparently enhances recruitment of mast cell as well as dendritic cell precursors into the tissue during systemic treatment. These findings and the observed adverse clinical effects in the present patient make it unlikely that GM-CSF monotherapy will be beneficial for the treatment of mastocytosis.

Adult↗

Systemic mastocytosis associated with acute myeloid leukaemia: report of two cases and detection of the c-kit mutation Asp-816 to Val.

A subset of patients with systemic mastocytosis (SM) develop acute myeloid leukaemia (AML). However, little is known about the biology of such leukaemias and their relationship to the mast cell (MC) lineage. We report on two female patients who suffered from SM and AML. According to FAB criteria, the leukaemias were classified as AML-M4 (patient 1) and AML-MO (patient 2). The coexistence of the two distinct neoplasms (AML and SM) was demonstrable by immunostaining of serial bone marrow (BM) sections with monoclonal antibodies (mAb). In particular, the MC infiltrates were found to react with mAb against MC-tryptase and MC growth factor receptor c-kit (CD117), but not with mAb to CD15 or CD34. In contrast, the AML blasts were immunoreactive for CD15 (patient 1) or CD34 (patient 2), but did not express tryptase. The c-kit point mutation Asp-->Val at codon 816, considered to play a role in the transformation of MC progenitors, was detected in patient 1 in a BM cell fraction containing 4% MC. However, no c-kit mutation was found in pure AML blasts (<1% MC). These findings argue against an evolution of the AML clone from neoplastic MC or MC-committed progenitors.

Acute Disease↗

Intranasal salmeterol inhibits allergen-induced vascular permeability but not mast cell activation or cellular infiltration.

BACKGROUND: Salmeterol is a long-acting beta2-adrenergic agonist that is widely used in the treatment of asthma. It has been suggested that non-bronchodilator actions of salmeterol may contribute to its efficacy. OBJECTIVE: To further evaluate the potential non-bronchodilator actions of salmeterol in vivo, using a model of nasal challenge with allergen. METHODS: Twelve asymptomatic subjects with seasonal allergic rhinitis participated in a randomized, double-blind, placebo-controlled crossover trial of the effects of a single dose of 100 microg of salmeterol on the response to allergen challenge. Sneezing and symptom scores, and levels of histamine and albumin in nasal lavages, were measured throughout the protocol. Concentrations of tryptase, prostaglandin D2 and lysozyme were measured during the acute allergic response, while levels of IL-3, IL-5 and IL-8 were measured at later time points. Numbers of eosinophils and of total white blood cells were also recorded. RESULTS: Salmeterol did not affect sneezing or symptom scores at any point. During the immediate response to allergen challenge, mast cell activation, reflected by concentrations of histamine, tryptase and prostaglandin D2, and serous glandular secretion, assessed by measurements of lysozyme, were unaffected by salmeterol treatment but vascular permeability, reflected by concentrations of albumin in nasal lavages, was significantly reduced. At later time points, salmeterol had no effect on levels of histamine or albumin and did not affect cellular infiltration. Concentrations of IL-3, IL-5 and IL-8 were not increased by allergen challenge in these subjects, so the effects of salmeterol could not be evaluated. CONCLUSIONS: Treatment with a single dose of salmeterol had no effect on activation of mast cells or cellular infiltration but inhibited vascular permeability. The ability of salmeterol to inhibit antigen-induced vascular permeability may contribute to its therapeutic efficacy in asthma.

Administration, Intranasal↗

Eosinophils are a feature of upper and lower airway pathology in non-atopic asthma, irrespective of the presence of rhinitis.

BACKGROUND: Asthma and rhinitis often co-exist and there are data to suggest that they may be two ends of the same disease spectrum. Immunohistochemical studies have shown that eosinophilia in the airways is a feature of rhinitic patients without asthma. OBJECTIVE: The aim of our study was to examine whether cellular infiltration exists in the nasal mucosa of asthmatics even in the absence of symptoms and signs of rhinitis. METHODS: Nasal mucosa biopsies were taken from 27 non-atopic subjects and comprised nine asthmatic rhinitic patients (AR), eight asthmatic non-rhinitic patients (ANR) and 10 healthy control subjects (N). Bronchial mucosa biopsies were also taken simultaneously from some of the patients (n = 10) to determine whether there was an association between cellular infiltration in the nose and the lungs. The alkaline phosphatase-anti-alkaline phosphatase (APAAP) method was used on 6 microm thick cryostat sections using monoclonal antibodies against T cells (CD4, CD8), eosinophils (EG2) and mast cells (mast cell tryptase). Slides were counted blind and results expressed as cells per field. RESULTS: The results showed that eosinophil counts were higher in both asthma groups compared with control nasal biopsies (median values AR 8.3, ANR 9.2, N 2.1 cells per field, P < 0.01). Furthermore, there was a significant correlation between eosinophil cell counts in the nose and the airways (r = 0.851 P < 0.001). No differences in eosinophil numbers were detected between the two groups of asthmatics. Also, no differences were noted for any other cell type (i.e. CD4, CD8, tryptase) among the three study groups. CONCLUSIONS: These results show that eosinophil infiltration was present in the nasal mucosa of asthmatic patients even in the absence of rhinitis, and add further support to the hypothesis that asthma and rhinitis are clinical expressions of the same disease entity.

Adult↗

Anaphylaxis to chlorhexidine. Case report. Implication of immunoglobulin E antibodies and identification of an allergenic determinant.

BACKGROUND: There are many reports of allergic reactions, including anaphylaxis, following exposure to chlorhexidine. Reactions may occur via contact with the skin and mucous membranes or from catheters treated with the antibacterial agent. Apart from implicating chlorguanide in immunoglobulin (Ig) E antibody-binding studies on serum from an anaphylactic patient, little work has been done on the molecular basis of recognition of the agent in sensitive subjects. OBJECTIVES: The molecular basis of IgE-binding to chlorhexidine was closely examined with the view of defining its fine structural recognition features by antibodies from a subject who experienced anaphylaxis following contact with the antiseptic. METHODS: Tryptase determinations, different drug-solid phases, immunoassays and quantitative hapten inhibition studies with chlorhexidine and selected structural analogues were employed together with serum from the anaphylactic patient. Results were analysed to define the complete drug allergenic determinant and to identify the important structural features complementary to the IgE antibody combining sites. RESULTS: The subject's serum tryptase levels sampled after the reaction were elevated and employment of a chlorhexidine-EA Sepharose solid phase showed the presence of serum IgE antibodies to the drug. Lack of inhibition by 4-chlorophenol and other selected substituted phenyl compounds showed that the terminal groups at each end of the chlorhexidine molecule, alone, did not account for antibody recognition of the antibacterial agent. Although chlorguanide and alexidine, the structures of which each comprise part of the chlorhexidine molecule, showed significant inhibition of the binding of IgE antibodies to chlorhexidine, neither compound was as potent an inhibitor as chlorhexidine itself. Two molecules of chlorguanide make up the symmetrical molecule of chlorhexidine while the interior structure of alexidine (that is excluding the terminal 2-ethylhexyl groups) is identical to part of the chlorhexidine molecule. CONCLUSIONS: Taken together, for this patient, these results lead to the conclusion that the whole chlorhexidine molecule is complementary to the IgE antibody combining sites and that the 4-chlorophenol, biguanide and hexamethylene structures together comprise the allergenic determinant. Hence, like one of the trimethoprim determinants identified, but unlike most drug allergenic determinants identified so far, the chlorhexidine allergenic determinant identified here encompasses the entire molecule.

Aged↗

Mast cells and T cells in Kimura's disease express increased levels of interleukin-4, interleukin-5, eotaxin and RANTES.

BACKGROUND: Kimura's disease (KD) is a chronic inflammatory disorder characterized by tumours in the head and neck region, enlarged lymph nodes, increased eosinophil counts andhigh serum IgE. Mast cells are known to play a central role in IgE-mediated allergic diseases through the release of inflammatory mediators like IL-4, IL-5 and chemokines. We hypothesized that mast cells may play a role in the pathogenesis of KD by regulating eosinophilic infiltration and IgE synthesis. OBJECTIVE: In order to investigate the role of mast cells in the pathogenesis of KD, we examined the expression of cytokines/chemokines in the lesions of KD. METHODS: We examined the number of tryptase+ cells, EG2+ cells, CD3+ cells, IL-4+ cells, IL-5+ cells, eotaxin+ cells, RANTES+ cells and CCR3+ cells in five specimens of KD versus normal tissues by immunohistochemistry. The sources of IL-4, IL-5, eotaxin and RANTES and the expression of CCR3 were examined by immunostaining of serial sections with antibodies to IL-4, IL-5, eotaxin, RANTES and CCR3, and antibodies to tryptase, ECP (EG2) and CD3. RESULTS: Mast cells, activated eosinophils, T cells, IL-4+ cells, IL-5+ cells, eotaxin+ cells, RANTES+ cells and CCR3+ cells were all increased in the lesions of KD as compared with those in normal tissue. Mast cells and T cells were the major source of IL-4, whereas mast cells, T cells and activated eosinophils were the main source of IL-5. Mast cells, T cells and activated eosinophils were the main source of eotaxin and RANTES. CONCLUSIONS: The number of IL-4, IL-5, eotaxin and RANTES-expressing mast cells and T cells were increased in the lesions of KD. As mast cells are lesional resident cells, these cells may play an important role in the pathogenesis of KD by regulating IgE synthesis and orchestrating eosinophilic infiltration.

Adult↗

Polymorphic eruption of pregnancy and herpes gestationis: comparison of granulated cell proteins in tissue and serum.

Polymorphic eruption of pregnancy (PEP) and herpes gestationis (HG) are pregnancy-related dermatoses of unknown aetiology with eosinophil infiltration which, at early stages, may show similar clinical and histopathological features. To determine the relative contributions of eosinophils, neutrophils and mast cells to the pathogenesis of PEP and HG through deposition of granule proteins, we studied tissue and serum from 15 patients with PEP and 10 with HG. Using indirect immunofluorescence with antibodies to human eosinophil granule major basic protein (MBP), eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), neutrophil elastase and mast cell tryptase, we determined and compared cellular and extracellular staining patterns in lesional skin biopsy specimens and, using immunoassay, measured MBP, EDN, and ECP in patients' sera. Eosinophil infiltration and extracellular protein deposition of all three eosinophil granule proteins were present in both PEP and HG indicating a pathogenic role for eosinophils in both diseases. Staining for eosinophil granule proteins was especially prominent in urticarial lesions and around blisters in HG. EDN and ECP serum levels in PEP and ECP serum levels in HG were significantly increased compared with those in normal pregnant and normal nonpregnant serum. Neutrophils were more prominent in HG specimens than in PEP specimens; extracellular neutrophil elastase was minimally present and similar in both diseases. Mast cell numbers and extracellular tryptase deposition did not differ between the two diseases and did not differ from mast cell counts in skin of normal pregnant women. This study shows that eosinophil granule proteins are deposited extracellularly in tissue and are increased in serum in both PEP and HG. Moreover, eosinophil involvement in the two diseases is more consistent than neutrophil and mast cell involvement. Comparatively, tissue eosinophil infiltration and extracellular protein deposition is more extensive in HG than in PEP, suggesting that eosinophil involvement is greater in the pathogenesis of HG than PEP and similar to that found in bullous pemphigoid.

Biopsy↗

High-affinity immunoglobulin E receptor (Fc epsilon RI)-bearing eosinophils, mast cells, macrophages and Langerhans' cells in allergen-induced late-phase cutaneous reactions in atopic subjects.

We have used in situ hybridization (ISH) and immunohistochemistry (IHC) to investigate the kinetics of the expression for Fc epsilon RI mRNA (alpha-, beta- and gamma-chains), the alpha-chain protein product, as well as the phenotype of the mRNA- or protein-positive cells in allergen-induced late-phase skin reactions in atopic subjects. Compared with diluent controls, there were significant increases in the total number of mRNA+ cells for the alpha-, beta- and gamma-chains for Fc epsilon RI at all time-points (6, 24 and 48 hr) after allergen challenge (P < 0.01). By double IHC/ISH significant increases in alpha-, beta- and gamma-chain mRNA+ macrophages, eosinophils, mast cells and CD1a+ cells were also observed after allergen challenge (P < 0.05). The distribution of Fc epsilon RI subunit (alpha-, beta-, or gamma-chain) mRNA+ co-localization was CD68+ macrophages (42-47%), EG2+ eosinophils (33-39%), tryptase+ mast cells (5-11%) and CD1a+ Langerhans' cells (2-4%). Using single IHC, significant increases in the total number of Fc epsilon RI protein+ cells (P < 0.01) were observed 24 and 48 hr after allergen challenge. Double IHC showed that the distribution of Fc epsilon RI+ cells was tryptase+ mast cells (33%), CD68+ macrophages (36%), EG2+ eosinophils (20%), CD1a+ Langerhans' cells (4%) and unidentified cells (7%), at the 24-hr allergen-challenged sites. These observations suggest that the cutaneous late-phase reaction in man is associated with up-regulation of Fc epsilon RI on eosinophils, macrophages, mast cells and Langerhans' cells.

Allergens↗

Increased mast cells in the irritable bowel syndrome.

Mast cells (MC) release potent mediators which alter enteric nerve and smooth muscle function and may play a role in the pathogenesis of the irritable bowel syndrome (IBS). The aim of this study was to determine if MC were increased in the colon of IBS patients compared to controls. Biopsy specimens were obtained from the caecum, ascending colon, descending colon and rectum of 28 patients: 14 IBS (Rome criteria); seven normal; and seven inflammatory controls. Tissue was stained immunohistochemically using a monoclonal mouse antibody for human mast cell tryptase (AA1). Tissue area occupied by tryptase-positive MC (volume density of mast cells) was quantified by image analysis. The number of plasma cells, lymphocytes, eosinophils, neutrophils and macrophages were each graded semiquantitatively (0-4) in haematoxylin and eosin stained sections. Mast cell volume density was significantly (P < 0.05) higher in IBS (0.91 +/- 0.18; CI 0.79; 1.0) than normal controls (0.55 +/- 0.14; CI 0.40; 0.69) in the caecum but not at other sites. Apart from MC, there was no evidence of increased cellular infiltrate in the IBS group. MC were significantly increased in the caecum of IBS patients compared to controls. The multiple effects of the intestinal mast cell alone, or as a participant of a persistent inflammatory response, may be fundamental to the pathogenesis of IBS.

Adult↗

Characterization of a human basophil-like cell line (LAMA-84).

LAMA-84, a human leucocytic cell line, which upon establishment was described as having megakaryocytic, erythroid and granulocytic characteristics, was analysed for expression of various differentiation markers. In addition to some of the previously described phenotypic characteristics, this cell line was found to express mRNA for several proteins characteristic for basophilic leucocytes and mast cells. The authors show that LAMA-84 cells express mRNA for the mast cell tryptase, the proteoglycan core protein, carboxypeptidase A and the alpha and beta chains of the high affinity IgE receptor (Fc epsilon RI). The authors examined the potential of LAMA-84 to differentiate in serum-free medium or after DMSO or PMA treatment. Depending on the inducing factor, surface expression of the Fc epsilon RI alpha-chain was increased from 20% to 35-50% of the cells and mRNA levels for tryptase were increased in serum-free medium and after DMSO treatment. LAMA-84 was found to express CD13, CDw17, CD29, CD33, CD40, CD45 and CD117. Furthermore, mRNA for the eosinophil/basophil markers Charcot-Leyden crystal (CLC) protein and the major basic protein (MBP), as well as the erythrocyte differentiation marker alpha-globin, was detected. However, the authors observed only trace amounts of mRNA for another erythroid differentiation marker (glycophorin), trace amounts of the megakaryocytic marker GPIIIa, and no detectable level of GPIb alpha. By comparing the expression pattern of a panel of differentiation markers in LAMA-84, and a second human cell line (KU812) expressing a basophil phenotype, it is evident that these cell lines, which presently are the only two cell lines identified with basophilic characteristics, share a large number of phenotypic characteristics.

Antigens, Surface↗

Differentiation between ulcerative colitis and Crohn's disease by a quantitative immunohistochemical evaluation of T lymphocytes, neutrophils, histiocytes and mast cells.

Mucosal biopsy criteria has limited validity in terms of discrimination between ulcerative colitis (UC) and Crohn's disease (CD). The aim of this study was to set up quantitative immunohistochemical criteria, with a special focus on inflammatory cell distribution within individual specimens and throughout the large bowel. Quantitative evaluation was performed for the density of CD8+, CD45RO+, neutrophil elastase+, CD68+ and mast cell tryptase+ cells in affected and unaffected mucosa taken from 41 patients with UC and 61 patients with CD. Each slide was examined at the highest and lowest density fields, which were further divided into the upper and deeper half of mucosa. Multiple logistic regression analysis using 51 features as independent variables constructed a predictive equation finding the probability of UC (PUC), and the diagnostic categories were subsequently defined based on a receiver-operating characteristic curve. The analysis disclosed five significant features suggesting UC; these implied intense infiltration of CD8+ and mast cell tryptase+ cells, diffuse infiltration of neutrophil elastase+ and CD68+ cells, and continuous infiltration of CD45RO+ cells. The criteria consisted of three diagnostic categories, 'suggestive of UC (PUC > or = 0.7)', 'indeterminate (0.3 < PUC < 0.7)', and 'suggestive of CD (PUC < or = 0.3)'; the criteria had values for sensitivity and specificity exceeding 95%. The immunohistochemical criteria distinguishing UC from CD may help to confirm the diagnosis in patients with ambiguous endoscopic and histological diagnosis.

Biopsy↗

The ascomycin macrolactam pimecrolimus (Elidel, SDZ ASM 981) is a potent inhibitor of mediator release from human dermal mast cells and peripheral blood basophils.

BACKGROUND: The ascomycin macrolactam pimecrolimus (Elidel, SDZ ASM 981) has recently been developed as a novel and cell-selective inhibitor of inflammatory cytokine secretion; it has fewer adverse effects than currently available drugs. OBJECTIVE: In this study, we investigated the capacity of pimecrolimus to directly inhibit in vitro mediator release from human skin mast cells and basophils. METHODS: Purified cutaneous mast cells or basophil-containing peripheral blood leukocytes were obtained from healthy human donors and preincubated with pimecrolimus (0.1 nmol/L to 1 micromol/L) in the absence or presence of its specific antagonist (rapamycin), cyclosporin A (100 nmol/L to 1 micromol/L), or dexamethasone (1 micromol/L) and then stimulated with anti-IgE or with calcium ionophore A23187 plus phorbol myristate acetate. Cell supernatants were kept for analysis of histamine, tryptase, LTC4, and TNF-alpha. RESULTS: Pimecrolimus caused a strong and dose-dependent inhibition of anti-IgE--induced release of histamine from mast cells and basophils (maximally 73% and 82%, respectively, at 500 nmol/L pimecrolimus) and of mast cell tryptase (maximally 75%) and a less pronounced inhibition of LTC4 (maximally 32%) and of calcium ionophore plus phorbol myristate acetate--induced mast cell TNF-alpha release (90% maximum at 100 nmol/L pimecrolimus). In contrast, inhibition achieved during mast cell histamine release was maximally 60% with cyclosporin A and only 28% with dexamethasone. CONCLUSION: These data demonstrate a marked inhibitory capacity of pimecrolimus on mediator release from human mast cells and basophils with a potency exceeding that of cyclosporin A and dexamethasone. Pimecrolimus might thus be expected to be effective in the treatment of mast cell-- and basophil-dependent diseases.

Anti-Inflammatory Agents, Non-Steroidal↗

T-cell proliferation induced by local application of LPS in the nasal mucosa of nonatopic children.

BACKGROUND: Recently, there has been a great deal of interest in the role of bacterial products in altering the allergic immune response in early life. OBJECTIVE: We sought to develop a model of bacterial inflammation in human subjects to characterize the ex vivo response to LPS in the nasal mucosa of young nonatopic children. METHODS: Using the explant technique, we cultured nasal mucosa in the presence or absence of increasing concentrations of LPS (0.001-1 microg LPS/mL) for 24 hours. Immunocytochemistry and in situ hybridization were used to phenotype the cells and cytokines in the explant, and immunofluorescence was used to study proliferation of T cells in explants cultured with LPS and 5-bromo-2'-deoxyuridine (BrdU). RESULTS: CD68, CD3, tryptase, elastase, IFN- gamma IL-12, and IL-10 immunoreactivity was detected in unstimulated tissue. LPS stimulation caused a dose-dependent increase in the number of CD3(+) (n = 7, P <.05), CD68(+) (n = 7, P <.01), elastase-positive (n = 7, P <.01), tryptase-positive (n = 7, P <.05), IL-2 -positive (n = 6, P <.05), IL-12 -positive (n = 6, P <.05), and IFN- gamma-positive (n = 6, P <.05) cells compared with media alone. LPS had no effect on major basic protein, IL-4, IL-5, or IL-13 immunoreactivity. LPS (0.1 microg/mL) caused an increase in the number of BrdU-positive cells as early as 2 hours after incubation (n = 8, P <.001). The maximal BrdU immunoreactivity was seen 24 hours after incubation with LPS, at which time approximately 70% of BrdU- positive cells were CD3(+) T cells. CONCLUSIONS: Our results suggest that LPS is capable of inducing local inflammation, T(H)1 cytokine immunoreactivity, and proliferation of CD3(+) activated T cells in the absence of de novo cell recruitment. This model holds promise for future studies investigating the importance of bacterial products in regulating local immune function in young atopic children.

Administration, Intranasal↗

Ofuji's disease: a report on 20 patients with clinical and histopathologic analysis.

BACKGROUND: Ofuji's disease, also referred to as classic eosinophilic pustular folliculitis, is a rare dermatosis of unknown origin for which there is no uniformly effective treatment. OBJECTIVES AND METHODS: Twenty patients with Ofuji's disease (classic eosinophilic pustular folliculitis) evaluated in our department from January 1978 to June 1999 were studied clinically and histopathologically. Laboratory data, treatments, and clinical courses were evaluated in 12 of these individuals. RESULTS: Nissl modified staining revealed moderate increases of mast cells around hair follicles and sebaceous glands in all 20 patients; the majority of the infiltrating mast cells were tryptase-positive and chymase-negative. Eight of 11 patients treated with oral indomethacin responded completely. CONCLUSIONS: Indomethacin is an effective therapy for Ofuji's disease. Tryptase-positive and chymase-negative mast cells might play some role in the pathogenesis of Ofuji's disease.

Adolescent↗

Multiple elements of the allergic arm of the immune response modulate autoimmune demyelination.

Analysis of mRNA from multiple sclerosis lesions revealed increased amounts of transcripts for several genes encoding molecules traditionally associated with allergic responses, including prostaglandin D synthase, histamine receptor type 1 (H1R), platelet activating factor receptor, Ig Fc epsilon receptor 1 (Fc epsilon RI), and tryptase. We now demonstrate that, in the animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), mediated by T helper 1 (Th1) T cells, histamine receptor 1 and 2 (H1R and H2R) are present on inflammatory cells in brain lesions. Th1 cells reactive to myelin proteolipid protein expressed more H1R and less H2R than Th2 cells. Pyrilamine, an H1R antagonist, blocked EAE, and the platelet activating factor receptor antagonist CV6209 reduced the severity of EAE. EAE severity was also decreased in mice with disruption of the genes encoding Ig Fc gamma RIII or both Fc gamma RIII and Fc epsilon RI. Prostaglandin D synthase and tryptase transcripts were elevated in EAE brain. Taken together, these data reveal extensive involvement of elements of the immune response associated with allergy in autoimmune demyelination. The pathogenesis of demyelination must now be viewed as encompassing elements of both Th1 responses and "allergic" responses.

Animals↗

Two types of human mast cells that have distinct neutral protease compositions.

Two human mast cell types were identified by immunohistochemical techniques in skin, lung, and small intestine. One type contains the neutral proteases, tryptase and chymotryptic proteinase, and is termed the TC mast cell. The second type contains only tryptase and is termed the T mast cell. Both types are fixed better by Carnoy's fluid than by formalin. The percentage of mast cells accounted for by the T type was 12 in skin; 98 in mucosa and 13 in submucosa of small intestine; and 77 in bronchial/bronchiolar subepithelium, about 97 in bronchial/bronchiolar epithelium, and 93 in alveoli of lung. Dispersed lung cells contained 90% T mast cells. The mean area of TC mast cells (76 micron2) was slightly larger than that of T mast cells (66 micron2); however, there was such extensive overlap that individual mast cells belonging to different types could not be distinguished on the basis of size. The recognition of human mast cell types with distinct protease compositions suggests a higher level of complexity of human mast cell-mediated reactions than heretofore appreciated.

Endopeptidases↗

Development of human mast cells in vitro.

Nucleated cells of human umbilical cord blood were cocultured with mouse skin-derived 3T3 fibroblasts. After 7-8 weeks in culture, when the number of the other hematopoietic cells declined, metachromatic granule-containing mononuclear cells appeared in the cultures, and the number of the cells increased up to 12 weeks. After 11-14 weeks in culture, the metachromatic mononuclear cells comprised a substantial portion of the cultured cells. These cells contained 1.8-2 micrograms of histamine per 10(6) cells and bore receptors for IgE. All of the cells contained tryptase in their granules. Electron microscopic analysis showed that these cells were mature human mast cells, clearly different from the basophilic granulocytes or eosinophils that arise in a variety of circumstances in cord blood cell cultures. Most of the cultured mast cells expressed some granules with regular crystalline arrays and contained both tryptase and chymase, and thus resembled human skin mast cells.

Antigens, CD↗