A 24-year-old man comes to the office due to paroxysmal episodes of breathlessness and wheezing for the past 6 months. He does not recognize any triggers for these episodes and reports they are not associated with exercise or stress. The patient has no history of recent illness. He had eczema as a child. The patient has no other medical conditions and takes no medications. Vital signs are within normal limits. Lung examination shows good air movement and no wheezing. Sputum microscopy reveals many granule-containing cells and crystalloid masses. The sputum findings in this patient are a direct result of which of the following cytokines?

Question

A 24-year-old man comes to the office due to paroxysmal episodes of breathlessness and wheezing for the past 6 months.  He does not recognize any triggers for these episodes and reports they are not associated with exercise or stress.  The patient has no history of recent illness.  He had eczema as a child.  The patient has no other medical conditions and takes no medications.  Vital signs are within normal limits.  Lung examination shows good air movement and no wheezing.  Sputum microscopy reveals many granule-containing cells and crystalloid masses.  The sputum findings in this patient are a direct result of which of the following cytokines?

Quizplus · Accepted Answer

11ec160b_3b2d_ef58_9249_eb4028c65ee9_MD0001_00 This young patient with paroxysmal dyspnea and wheezing likely has asthma, a disease characterized by airway inflammation, bronchial hyperreactivity, and a variable airflow obstruction. Symptoms that cannot be related to pulmonary infection, inhalation of irritants, stress, exercise, or aspirin ingestion should raise suspicion for atopic (extrinsic) asthma. Atopic asthma occurs in genetically predisposed individuals; patients often have a family history of asthma, allergies, or eczema. Sputum microscopy classically demonstrates elevated levels of eosinophils (granule-containing cells) with Charcot-Leyden crystals (bipyramidal-shaped accumulations of eosinophil membrane protein). Atopic asthma occurs due to an excessive T_H2-mediated reaction to environmental aero-antigens (eg, pollen, pet dander). In response to allergic stimuli, these cells secrete IL-5, a critical cytokine for eosinophilic activation, recruitment, and prolonged survival in the bronchial mucosa. T_H2 cells also synthesize IL-4, which stimulates IgE formation by plasma cells. As with other type I hypersensitivity reactions, these antigen-specific antibodies bind to receptors on mast cells, and repeated exposure induces mast cell degranulation. This leads to bronchoconstriction, increased vascular permeability, and increased mucus production associated with acute asthma exacerbations. Eosinophils also release inflammatory mediators (ie, major basic protein, eosinophil cationic protein) that damage the bronchial epithelium later in the immune response. (Choice A) Although IL-1 release from macrophages is involved in asthma pathogenesis, it is not a specific cytokine. IL-1 release is a component of almost all inflammatory processes and does not necessarily cause eosinophil infiltration. (Choice C) IL-12 functions to promote the differentiation of T_H1 cells; it is not directly involved in eosinophil recruitment. (Choice D) Interferon-gamma is secreted by helper T cells and functions to activate macrophages, thereby promoting adaptive immunity against intracellular pathogens. It is not directly chemotactic for eosinophils. (Choice E) Transforming growth factor beta (TGF-β) is a growth factor involved in tissue regeneration and repair; high levels are associated with subepithelial fibrosis and airway remodeling seen in chronic asthma. However, it is not chemotactic for eosinophils. Educational objective: Paroxysmal breathlessness and wheezing in a young patient that are unrelated to ingestion of aspirin, pulmonary infection, inhalation of irritants, and/or exercise should raise a strong suspicion for atopic (extrinsic) asthma. Classic sputum findings include eosinophils and Charcot-Leyden crystals. Eosinophils are recruited and activated by IL-5 secreted by T_H2 type T cells.

A 24-Year-Old Man Comes to the Office Due to Paroxysmal