Human dermal mast cells contain and release tumor necrosis factor alpha, which induces endothelial leukocyte adhesion molecule 1

Human eosinophils can express the cytokines tumor necrosis factor-alpha and macrophage inflammatory protein-1 alpha

By in situ hybridization, 44-100% of the blood eosinophils from five patients with hypereosinophilia and four normal subjects exhibited intense hybridization signals for TNF-alpha mRNA. TNF-alpha protein was detectable by immunohistochemistry in blood eosinophils of hypereosinophilic subjects, and purified blood eosinophils from three atopic donors exhibited cycloheximide-inhibitable spontaneous release of TNF-alpha in vitro. Many blood eosinophils (39-91%) from hypereosinophilic donors exhibited intense labeling for macrophage inflammatory protein-1 alpha (MIP-1 alpha) mRNA, whereas eosinophils of normal donors demonstrated only weak or undetectable hybridization signals for MIP-1 alpha mRNA. Most tissue eosinophils infiltrating nasal polyps were strongly positive for both TNF-alpha and MIP-1 alpha mRNA. By Northern blot analysis, highly enriched blood eosinophils from a patient with the idiopathic hypereosinophilic syndrome exhibited differential expression of TNF-alpha and MIP-1 alpha mRNA. These findings indicate that human eosinophils represent a potential source of TNF-alpha and MIP-1 alpha, that levels of expression of mRNA for both cytokines are high in the blood eosinophils of hypereosinophilic donors and in eosinophils infiltrating nasal polyps, that the eosinophils of normal subjects express higher levels of TNF-alpha than MIP-1 alpha mRNA, and that eosinophils purified from the blood of atopic donors can release TNF-alpha in vitro.

Mast cells in fibrotic lung disorders

Fibrotic lung disorders are chronic inflammatory diseases in which inflammatory processes in the lower respiratory tract injure the lung and modulate the proliferation of mesenchymal cells that form the basis of the fibrotic scar. The pathogenesis of fibrosis in fibrotic lung disorders remains unclear; however, recent attention has focused on the potential role of the mast cell in the genesis of fibrosis. To determine whether mast cells are implicated in the pathogenesis of lung fibrosis, mast cells were compared with the degree of fibrosis in transbronchial lung biopsy specimens from 49 patients with fibrotic lung disorders (16 sarcoidosis, 15 farmer's lung disease, 9 cryptogenic fibrosing alveolitis, 6 bronchiolitis obliterans organizing pneumonia, 3 histiocytosis X). In lung tissue of patients with fibrotic lung disorders, there was an increased number of mast cells in respect to the control group (98.6 +/- 7.7 vs 27.8 +/- 5.1 mast cells per square millimeter, p < 0.01). Mast cell counts in lung biopsy specimens were significantly correlated with the degree of fibrosis (r = 0.87, p < 0.001); 80.8 percent of mast cells were found in the alveolar septa, 9.6 percent within alveoli, 1.9 percent among alveolar lining cells, and 5 percent along blood vessels. No mast cells were located within alveoli in controls. Our data suggest that mast cells participate in chronic inflammation and that their presence is related to interstitial fibrosis in a much broader spectrum of fibrotic lung disorders.

Cytokines contribute to airway dysfunction in antigen-challenged guinea pigs: inhibition of airway hyperreactivity, pulmonary eosinophil accumulation, and tumor necrosis factor generation by pretreatment with an interleukin-1 receptor antagonist

The role of pro-inflammatory cytokines in an animal model of allergic lung disease was examined by use of an interleukin-1 receptor antagonist (IL-1ra) and a specific bioassay for tumor necrosis factor (TNF). Ovalbumin-sensitized guinea pigs exhibit a marked bronchial hyperreactivity (assessed by airway responsiveness to intravenous histamine) and pulmonary eosinophil accumulation (assessed by bronchoalveolar lavage) 24 h after challenge with aerosolized antigen. Exposure of animals to an aerosol of IL-1ra (50 micrograms over 30 min) immediately before antigen challenge resulted in a marked protection against bronchial hyperreactivity and pulmonary eosinophil accumulation compared with IL-1ra vehicle-pretreated animals. Additionally, we report for the first time generation of TNF bioactivity in the bronchoalveolar lavage of antigen-challenged animals, which was significantly reduced in animals exposed to aerosolized IL-1ra before challenge. These studies point to a key role for the cytokines IL-1 and possibly TNF in the pulmonary changes observed during allergic airway disease.

Mast cell cytokines in allergy and inflammation

Recent findings indicate that mast cells can influence biological responses through the production of cytokines and suggest that many allergic reactions and other biological processes may be regulated by a "mast cell-leukocyte cytokine cascade". This hypothesis proposes that certain biological responses are initiated by mast cell activation, resulting in the mast cell-dependent release of TNF-alpha and other cytokines which can promote the recruitment of eosinophils, neutrophils, and other effector cells. The recruited effectors then influence the progression of the response by providing additional sources of some cytokines which also can be elaborated by mast cells, as well as by producing other cytokines not known to be of mast cell origin.

Human lung mast cells and pulmonary macrophages produce tumor necrosis factor-alpha in sensitized lung tissue after IgE receptor triggering

Tumor necrosis factor (TNF) is considered to play a key role in the pathogenesis of allergic disorders. We examined TNF production in human lung fragments after IgE receptor triggering at mRNA and protein levels. IgE receptor triggering was performed by sensitizing lung fragments with monoclonal human IgE and then exposing them to anti-human IgE antibody. Cytotoxic activity against L929 cells appeared in the culture supernatant of lung fragments 2 h after IgE receptor triggering and increased for up to 4 h. This cytotoxic activity was completely neutralized by anti-human TNF antibody. Northern blot analysis demonstrated that 1.8-kb TNF mRNA transcripts in sensitized lung fragments were expressed as early as 1 h after IgE receptor triggering and continued up to 4 h. Immunohistochemical analysis revealed TNF localization in tissue mast cells, alveolar macrophages, tissue macrophages, and bronchial epithelial cells. Double staining with anti-TNF antibody and alcian blue clearly identified that lung mast cells are one of the TNF-positive cell types in the pulmonary tissue. With immunoelectron microscopy, TNF immunoreactivity was detected in the rough endoplasmic reticulum and the perinuclear spaces in tissue macrophages, and in the cytosol and the perinuclear spaces in bronchial epithelial cells. In addition, IgE was detected on the cell surface of mast cells, tissue macrophages, and alveolar macrophages. These results suggest that TNF is released from mast cells and pulmonary macrophages through IgE receptor triggering and may play a key role in the allergic reaction in human airway.

Analyzing mast cell development and function using mice carrying mutations at W/c-kit or Sl/MGF (SCF) loci

Mast cells have been implicated in a wide variety of biological responses, but identifying the nature and importance of the mast cell's specific contributions to these reactions has been difficult. W/Wv mice have mutations affecting the c-kit tyrosine kinase receptor which is encoded at the W locus and which is necessary for normal mast cell development. In W/Wv mice, the cells which ordinarily give rise to normal mast cell populations do not adequately respond to a major migration, survival, proliferation and maturation factor expressed in the microenvironments where mast cells ordinarily develop: the c-kit receptor ligand, SCF. As a result, W/Wv mice virtually lack tissue mast cells. However, adoptive transfer to W/Wv mice of immature mast cells derived in vitro from the bone marrow cells of the congenic normal (+/+) mice selectively repairs the mast cell deficiency of the W/Wv recipients. These "mast cell knock-in" mice can be used to analyze the expression of biological responses in tissues which differ only because they do or do not contain populations of mast cells. This approach permits identification and quantification of the specific contributions of the mast cell to biological responses expressed in the skin, gastrointestinal tract and other anatomical sites, and also greatly facilitates analysis of the mechanisms by which mast cells influence these responses.

Fatal and near-fatal anaphylactic reactions to food in children and adolescents

BACKGROUND AND METHODS

Reports of fatal or near-fatal anaphylactic reactions to foods in children and adolescents are rare. We identified six children and adolescents who died of anaphylactic reactions to foods and seven others who nearly died and required intubation. All the cases but one occurred in one of three metropolitan areas over a period of 14 months. Our investigations included a review of emergency medical care reports, medical records, and depositions by witnesses to the events, as well as interviews with parents (and some patients).

RESULTS

Of the 13 children and adolescents (age range, 2 to 17 years), 12 had asthma that was well controlled. All had known food allergies, but had unknowingly ingested the foods responsible for the reactions. The reactions were to peanuts (four patients), nuts (six patients), eggs (one patient), and milk (two patients), all of which were contained in foods such as candy, cookies, and pastry. The six patients who died had symptoms within 3 to 30 minutes of the ingestion of the allergen, but only two received epinephrine in the first hour. All the patients who survived had symptoms within 5 minutes of allergen ingestion, and all but one received epinephrine within 30 minutes. The course of anaphylaxis was rapidly progressive and uniphasic in seven patients; biphasic, with a relatively symptom-free interval in three; and protracted in three, requiring intubation for 3 to 21 days.

CONCLUSIONS

Dangerous anaphylactic reactions to food occur in children and adolescents. The failure to recognize the severity of these reactions and to administer epinephrine promptly increases the risk of a fatal outcome.

Role of adhesion molecules in cutaneous inflammation and neoplasia

There is accumulating evidence that the expression of certain adhesion molecules has important consequences for understanding patterns of cell movement in normal and pathologically altered skin. This paper reviews recent work regarding the role of integrins and other adhesion molecules (ICAM-1, VCAM-1, PECAM-1, LECAM-1, and ELAM-1) in cutaneous inflammation and neoplasia, and presents a unifying hypothesis which outlines how sequential expression of cytokines and adhesion molecules in evolving inflammation may alter the nature of the cellular response.

Eccrine syringofibroadenoma (Mascaro): an ultrastructural study

To confirm the eccrine acrosyringeal differentiation of eccrine syringofibroadenoma (ESFA) and to elucidate the histogenesis of its angiofibrotic stroma, a case of ESFA from a 45-year-old man was examined by light and electron microscopy. Histologically, the parenchyma featured anastomosing, slender epithelial cords containing small cuboidal cells and occasional duct-like structures. The stroma had increased numbers of mast cells, increased capillaries with swollen endothelial cells, and prominent fibrosis. Ultrastructurally, the following findings were characteristic of ESFA: a) abundant glycogen particles in epithelial cells, b) numerous intracytoplasmic and extracellular spaces lined with microvilli, c) intraepithelial duct formation, consisting of microvilli, vesicles, rod-shaped dense bodies, multivesicular dense bodies, and peripheral network of tonofilaments, and d) large numbers of mast cells, closely associated with fibroblasts, surrounding increased numbers of capillaries containing swollen endothelial cells. These ultrastructural features support the acrosyringeal differentiation of ESFA. We hypothesize that mast cell hyperplasia and degranulation may play an important role in the formation of the angiofibrotic stroma.

Polymorphonuclear neutrophil contribution to induced tolerance to bacterial lipopolysaccharide

The objective of this study was to investigate mechanisms by which polymorphonuclear neutrophils (PMNs) contribute to the tolerance induced by repeated lipopolysaccharide (LPS) injections. Tolerance was developed by daily intraperitoneal injections of sublethal doses of LPS for 4 days (LPS-tolerant group); controls were not pretreated (LPS-control group). Both groups were challenged with 9 mg/kg i.v. Escherichia coli LPS, a dose that resulted in 25% survival in LPS-control rats compared with 100% survival in LPS-tolerant rats. LPS injection caused an initial neutropenia in both groups. The neutropenia persisted throughout the experiment in LPS-control rats, whereas in LPS-tolerant rats the circulating PMN count increased dramatically; after 6 hours, the PMN count was 16-fold higher than that in LPS-control rats. Activation of circulating PMNs, PMN adhesion to nylon fibers, and tumor necrosis factor/cachectin activity were all increased in control rats given LPS. In contrast, LPS-tolerant rats had low activation of circulating PMNs, no trend for PMN adhesion to nylon fibers, and markedly reduced tumor necrosis factor activity. To determine whether neutropenia was associated with a trapping of PMNs in the microcirculation, we used a carbon perfusion technique 6 hours after LPS injection and examined histological sections of the myocardium. All of the arterioles and venules in both groups contained carbon; only capillaries showed evidence of obstruction. A significantly higher percentage of obstructed capillaries was observed in LPS-control rats than in LPS-tolerant rats. Obstruction of capillaries was consistently associated with trapped leukocytes. We conclude that PMN cytotoxicity induced by LPS involves microcirculatory entrapment and activation of PMNs. Repeated LPS pretreatment reduces dramatically circulating PMN activation and adhesion and is associated with an elevated circulating PMN count, a low degree of microvascular plugging, and survival after a normally lethal dose of LPS.