Eosinophils in Humoral and Cell-Mediated Responses
A. Arthur Gottlieb in Developments in Lymphoid Cell Biology, 2018
The function of eosinophils, which are a prominent cellular component of inflammatory, allergic, and immunologic reactions to antigen, is still veiled in obscurity despite more than a century of diligent research. Progress has been hampered in part because of a lack of clear understanding of the precise factors that induce an eosinophil reaction and a paucity of knowledge concerning the biochemical reactions of the enzymes carried by eosinophils. Although eosinophils are regarded as blood cells, their sojourn in blood vessels is relatively short, usually measured in minutes or at the most a few hours. "T" memory cells are involved in the transfer of both eosinophil and antitoxin responses to tetanus toxoid while "B" memory cells appear to be associated only with the humoral response. Eosinophils play a role in intercellular reactions and appear to form a link in the chain of transport for antigenic complexes between antigen-activated "T" memory cells and macrophages.
Eosinophilic Esophagitis
John F. Pohl, Christopher Jolley, Daniel Gelfond in Pediatric Gastroenterology, 2014
The symptoms of Eosinophilic esophagitis (EoE) are similar to gastroesophageal reflux disease (GERD), although the clinical manifestations of EoE can vary with age. The primary differential diagnosis for EoE is GERD, which may be differentiated histologically by changes localized to the distal esophagus, rather than the entire esophagus. EoE has a nearly worldwide distribution and has been reported in various countries in North America, South America, Asia, Europe, and Australia. The recognition of key modulators of eosinophil recruitment and function has important clinical implications. In addition to being potential targets for drug development, Numerous inflammatory mediators may also have a future role in the diagnosis and monitoring of the disease. Mucosal biopsy specimens should be obtained from the proximal and distal esophagus. Emerging data support a potential role of interleukin-5 biologic agents, such as reslizumab or mepolizumab, in the treatment of EoE.
Case 14: Allergic Asthma
Laurel J. Gershwin in Case Studies in Veterinary Immunology, 2017
Allergic respiratory disease is caused by inhalation of environmental allergens. Professional antigen-presenting cells called dendritic cells reside below respiratory airway epithelial cells and send projections to airway lumen that enable them to capture inhaled antigens. Dendritic cells then process these antigens internally and present a portion of antigen on their cell surface in conjunction with major histocompatibility complex (MHC) II. Asthma in cats is believed to result predominantly from a type I hypersensitivity response to aeroallergens under appropriate genetic and environmental influences. The chapter presents the case of Smokey. Smokey, a two-year-old spayed female domestic shorthaired cat was presented to her veterinarian with an acute onset of respiratory distress. Smokey was diagnosed with chronic allergic asthma based on a combination of compatible clinical signs, peripheral eosinophilia, thoracic radiographic features, negative tests for lungworm, exclusion of heartworm-associated respiratory disease, and evidence of bronchoalveolar lavage fluid eosinophilia.
Emphysematous Phenotype is Characterized by Low Blood Eosinophils: A Cross-Sectional Study
Published in COPD: Journal of Chronic Obstructive Pulmonary Disease, 2017
Andriana I. Papaioannou, Konstantinos Kostikas, Anastasia Papaporfyriou, Leonidas Angelakis, Evgenia Papathanasiou, Georgios Hillas, Argyro Mazioti, Petros Bakakos, Nikolaos Koulouris, Spyros Papiris, Stelios Loukides
Sputum and blood eosinophils are proposed as candidate biomarkers for the identification of chronic obstructive pulmonary disease (COPD) patients at risk for exacerbation and treatment response. In this study, we evaluated the associations of eosinophils with the presence of emphysema in COPD patients. Induced sputum and blood eosinophil measurements were performed in consecutive COPD patients. Patients underwent lung function testing and high resolution computed tomography (HRCT) of the chest and the presence of emphysema was quantified. Patients with emphysematous lesions in ≥15% of the pulmonary parenchyma were considered having significant emphysema. Ninety-eight patients were included in the study. Patients with significant emphysema had lower blood eosinophil counts compared to patients without emphysema [median (IQR) 34.6 (0.0, 63.0) vs. 169.0 (110.0, 260.0) cells/µL, p < 0.001]; similar results were observed for the percentage (%) of blood eosinophils, but no difference was observed for sputum eosinophils. The differences were evident in frequent and non-frequent exacerbators and irrespective of the use of inhaled corticosteroids (ICS). Patients with significant emphysema in HRCT present lower levels of blood eosinophils and these differences were present irrespective of the frequent exacerbator history or the use of ICS. Blood eosinophils may not represent a clinically relevant biomarker in the presence of emphysema.
Role of eosinophils in protective immunity against secondary nematode infections
Published in Immunological Medicine, 2019
Infections with parasites, especially those involving nematodes that invade tissues, induce a strong Th2-type immune response, which increases immunoglobulin E and eosinophil levels in the blood and tissues. Eosinophils are not effective against all possible helminth infections, but are known to be effective against nematode larvae. In particular, when a host is re-infected by a species of nematode that it previously encountered, the activation of acquired immunity causes robust accumulation and activation of eosinophils that damages the nematode larvae. Eosinophil production and activation processes are mainly induced by interleukin (IL)-5, which is produced by Th2 cells and group 2 innate lymphoid cells, and eosinophils have been shown to generally participate in host defense, inflammation, and immunomodulation. Recently, several papers have reported host defense by non-antigen-specific immune activation, in which group 2 innate lymphoid cells and Th2 cells produce interleukin (IL)-5 and IL-13 in response to IL-33 stimulation. This immune activation is produced by migrating larvae of a species that differs from the species previously encountered. Eosinophils also play an important role in the eradication of migrating larvae. Thus, eosinophils contribute to host defense in both antigen-specific and non-antigen-specific manners.
Benralizumab: an updated treatment of eosinophilic asthma
Published in Expert Review of Respiratory Medicine, 2020
Breda Cushen, Andrew Menzies-Gow
Introduction: An estimated 5–10% of people with asthma have disease which remains uncontrolled despite maximal treatment with inhaled corticosteroids and long-acting beta-agonists. Benralizumab is currently licensed for use in patients with severe asthma who have an eosinophilic phenotype. Benralizumab depletes eosinophils by binding to the anti-IL5 receptor on the surface of eosinophils, mitigating the effect of IL-5 on eosinophil proliferation and survival, and induces natural killer cell-mediated eosinophil apoptosis. Areas covered: The authors review the mechanism of action and pharmacokinetic profile of Benralizumab and summarize the scientific data supporting its clinical efficacy and safety in severe asthma. Further, the authors highlight future studies of Benralizumab in asthma and other diseases. Expert opinion: Benralizumab lowers exacerbation rates, symptom burden, and oral glucocorticoid use, and improves lung function, in patients with severe eosinophilic asthma. Benralizumab is well tolerated and is an attractive choice for patients and physicians due to its eosinophil-depleting mechanism of action and less frequent dosing schedule. More data is needed to guide the selection of biologic therapy in severe asthma patients.