[A woman with a persistent cough]. / Een vrouw met een hardnekkig kuchje.

A 54-year-old, Turkish, unvaccinated woman presented with chronic cough. Bronchoscopy revealed an ulcer-like abnormality in the trachea. Surprisingly, the culture showed growth of non-toxigenic Corynebacterium diphtheriae. This is a rare pathogen that usually causes only local respiratory symptoms. At control bronchoscopy after antibiotic treatment the abnormalities were no longer seen.

Regulation and kinetics of platelet-activating factor and leukotriene C4 synthesis by activated human basophils.

BACKGROUND: Allergic disease is the result of an interplay of many different cell types, including basophils and mast cells, in combination with various inflammatory lipid mediators, such as platelet-activating factor (PAF) and leukotrienes (LT). LTC4 synthesis by human basophils has been studied quite extensively. However, not much is known about the synthesis of PAF by human basophils. OBJECTIVE: In this study, we have made a comprehensive comparison between the kinetics of PAF and LTC4 synthesis, in highly purified basophils, activated with different stimuli or with combinations of stimuli. METHODS: Synthesis of PAF and LTC4 by human basophils was determined with commercially available assay kits. The basophils were activated with C5a, fMLP, PMA, allergen or anti-IgE, in the absence and presence of IL-3 and/or in combination with elevation of cytosolic free Ca2+ by the sarcoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin. RESULTS: Most stimuli were found to induce both PAF and LTC4 synthesis. PAF synthesis and LTC4 release were enhanced by preincubation of the basophils with IL-3 or by elevation of cytosolic free Ca2+ by thapsigargin. Incubation of human basophils with IL-3 alone or thapsigargin alone did not result in detectable synthesis of PAF and LTC4, whereas the combination of the two resulted in high amounts of PAF and LTC4 synthesis. Depending on the stimulus used, LTC4 release was 5-100-fold higher than PAF synthesis. In addition, PAF, but not LTC4, was transiently detected, probably due to PAF degradation. LTC4 and PAF synthesis was strongly blocked by inhibitors of cytosolic phospholipase A2, indicating that this enzyme is involved in PAF and LTC4 synthesis by activated human basophils. CONCLUSION: This study provides a first comprehensive comparison of PAF and LTC4 synthesis in highly purified human basophils, stimulated with a variety of stimuli.

Influence of bronchial allergen challenge on histamine release by human basophils.

BACKGROUND: Basophils can be primed by cytokines such as interleukin (IL) -3, IL-5 or granulocyte macrophage-colony stimulating factor (GM-CSF). It has been described that the concentrations of these cytokines are enhanced at sites of allergic inflammation as well as systemic in allergic asthma. OBJECTIVE: To investigate the priming status of basophils as detected by thapsigargin-induced histamine release during bronchial allergen challenge. METHODS: Ten subjects allergic to house dust mite were challenged via an aerosol delivery system. Spontaneous leucocyte histamine release as well as histamine release induced by various stimuli was measured in vitro at several time points. In addition, lung function parameters, serum IL-5 and blood eosinophil counts were evaluated. RESULTS: We found no effect of bronchial allergen challenge upon spontaneous leucocyte histamine release, nor upon histamine release induced by anti-immunoglobulin (Ig) E, house dust mite extract, C5a, fMLP, IL-3, PMA+ thapsigargin or IL-3+ thapsigargin. However, the priming status of basophils as measured by thapsigargin-induced histamine release was enhanced at 24 h after bronchial allergen challenge. Analysis of the individual data showed a heterogeneous initial response (30 min, 6 h) followed by a predominant increase at 24 h after allergen challenge. This increase in the thapsigargin-induced histamine release correlated with the increase in serum IL-5 levels at 24 h after allergen challenge. CONCLUSION: The priming status of human basophils as measured by thapsigargin-induced histamine release is enhanced 24 h after allergen challenge.

Basophils from patients with allergic asthma show a primed phenotype.

BACKGROUND: IL-3, IL-5, and GM-CSF are not able to induce histamine release in purified basophils of nonallergic donors. However, we have recently found that preincubation with 2 micromol/L thapsigargin, which induces a rise in intracellular free calcium ions, renders human basophils extremely sensitive for IL-3, IL-5, or GM-CSF, leading to enhanced histamine release. Histamine release was also induced in the reverse order (first cytokine and then thapsigargin). OBJECTIVE: Because these cytokines are supposed to be increased in allergic inflammation, we examined whether basophils of patients with allergic asthma showed an enhanced response to thapsigargin. METHODS: We measured the histamine release induced by thapsigargin in a group of allergic asthmatic subjects (n = 24) and compared this response with those of 3 control groups. The control groups consisted of healthy control subjects (group 1, n = 21); patients with a nonallergic, nonasthmatic lung disease (group 2, n = 22); and patients with nonallergic asthma (group 3, n = 9). RESULTS: There was no difference in spontaneous histamine release. Also, no significant difference in histamine release was found when anti-IgE or formyl-methionyl-leucyl-phenylalanine was used as a stimulus. Histamine release induced by IL-3 alone or a combination of IL-3 and thapsigargin also did not differ. In contrast, basophils from the group with allergic asthma showed a significantly higher percentage of histamine release induced by thapsigargin (38.2% +/- 13.2%) than did basophils from the 3 control groups (healthy control subjects, 22.5% +/- 6.9%; subjects with lung disease, 24.9% +/- 8.9%; subjects with nonallergic asthma 15.0% +/- 3.0%; all mean +/- SD). CONCLUSION: These data indicate that basophils in peripheral blood of subjects with allergic asthma have a primed phenotype and that thapsigargin-induced histamine release is a practical tool to study this phenomenon.

Degranulation of human basophils by picomolar concentrations of IL-3, IL-5, or granulocyte-macrophage colony-stimulating factor.

In most secretory cells, an increase in the cytosolic free Ca2+ concentration ([Ca2+]i) is associated with the exocytosis response. In this study we have evaluated the effect of thapsigargin on histamine release from purified (70% to 97% pure) human basophils of nonallergic donors. Thapsigargin (2 micromol/L), by inhibiting the uptake of Ca2+ in the stores of the endoplasmic reticulum, leads within 1 minute to a gradual increase in [Ca2+]i in human basophils. Incubation of basophils with thapsigargin by itself induced only a very small release of histamine (5.6% +/- 1.8%). However, under suboptimal conditions of stimulation with other agonists, preincubation of basophils with thapsigargin significantly enhanced histamine release. Most strikingly, addition of thapsigargin made basophils extremely sensitive for histamine release induced by IL-3 (maximum histamine release, 71% +/- 7%), IL-5 (maximum histamine release, 43% +/- 8%), or granulocyte-macrophage colony-stimulating factor (GM-CSF) (maximum histamine release, 57% +/- 10%). These cytokines by themselves did not induce histamine release in purified basophils. The effect of thapsigargin was mimicked to a limited extent by addition of platelet-activating factor. We conclude that depletion of the Ca2+ stores may be a critical event in the activation of receptor-mediated histamine release in human basophils.

The role of basophils in allergic disease.

During allergic disease, leucocytes infiltrate the affected tissues and release their mediators and cytokines. In this way, the local inflammatory process is induced and maintained. Basophilic granulocytes have been demonstrated in lung and sputum of allergic asthmatics, in nasal mucosa and secretion of allergic rhinitis patients, and in skin lesions of atopic dermatitis patients. The number of basophils correlates with the severity of the disease. Analysis of mediator profiles and cellular contents of lavages of nose, skin and lung during allergic late-phase reactions (LPR) have demonstrated histamine, but not tryptase or prostaglandin D2. The histamine-containing cells have been characterized as basophilic granulocytes. This indicates that infiltrating basophils but not mast cells are activated and release their inflammatory contents in the LPR. We are interested in the cellular mechanisms that determine the degranulation of basophils during LPR. Basophil activators, such as allergens and activated complement, are not present at these sites. However, cytokines that prime basophils but do not induce degranulation, such as interleukin-5 (IL-5) and granulocyte/macrophage colony-stimulating factor (GM-CSF), have been detected at sites of LPR. We have now observed that after emptying intracellular Ca2+ stores by means of the Ca2+ adenosine triphosphatase (ATPase) inhibitor, thapsigargin, basophils become extremely sensitive to stimuli that do not affect the Ca2+ stores themselves but that induce degranulation, such as the phorbolester, phorbol myristate acetate (PMA). The most interesting finding was that although both thapsigargin and IL-3, IL-5 or GM-CSF do not induce basophil degranulation by themselves, a 2 min preincubation of basophils with thapsigargin followed by addition of one of these cytokines resulted in extensive histamine release: IL-3 induced 71 +/- 7% histamine release (conc1/2max 6 pM), IL-5 induced 43 +/- 8% histamine release (conc1/2max 41 pM) and GM-CSF induced 57 +/- 10% histamine release (conc1/2max 140 pM). Interestingly, the effect of thapsigargin could be mimicked by platelet-activating factor (PAF) (range 10(-9) to 10(-6) M), although to a lesser extent. Our results indicate that basophil degranulation in tissues during late-phase reactions might be caused by a combination of mediators or cytokines depleting Ca2+ stores, as platelet-activating factor or thapsigargin do, concurrent with activation by interleukin-3, interleukin-5 or granulocyte/macrophage colony-stimulating factor. The response of the basophils towards these cytokines might also be influenced by cell adhesion events, such as binding of basophils via integrins. This is the subject of further study.