Page 593 - Clinical Immunology_ Principles and Practice ( PDFDrive )

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Immunological Mechanisms of Airway

Diseases and Pathways to Therapy

David B. Corry, Farrah Kheradmand, Amber Luong, Lavannya Pandit

The immunological airway diseases comprise a large and disparate include clear rhinorrhea, sneezing, postnasal drip, nasal pruritus,
group of respiratory disorders characterized by airway and and congestion, often in association with ocular symptoms, such
parenchymal inflammation that impairs sinus and lung function. as conjunctivitis and tearing. Based on symptom duration, AR is
The physiological importance of the airways, combined with now classified as “intermittent” or “persistent,” with severity of
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the need to respond immunologically to an extremely broad symptoms noted as “mild” or “moderate to severe.” Consequently,
range of particulate and gaseous aerosols, explains much of the AR can be categorized into four groups based on the combination
diverse nature of airway immune disorders and their dispropor- of above two categories of frequency and symptom severity.
tionately large effect on human health. The allergic respiratory Patients with persistent AR typically have daily symptoms all year
tract immune disorders covered in this chapter are among the round but can also show seasonal fluctuations in the severity of
most common of all human afflictions. their symptoms. The impact of symptoms on quality of life and
Allergic disorders have a common immune phenotype com- on productivity is reflected in the “mild” and “moderate–severe”
prising highly characteristic cellular, humoral, biochemical, and categorization.
molecular components, although individual variability means
that not all these immunological features are equally expressed. KEY CONCEPTS
The most studied and visually characteristic allergic immune
cells are eosinophils and tissue mast cells, which are easily Classification of Allergic Rhinitis
seen on conventional hematoxylin and eosin (H&E) staining Frequency of Symptoms Severity of Symptoms
of pathological specimens. Eosinophils may far outnumber all
other inflammatory cells. Less obvious on histochemical staining, Intermittent Mild
but equally important to allergic diseases, are B cells that secrete Symptoms present for No presence of sleep disturbance
<4 days a week
the antibody isotypes immunoglobulin E (IgE) and IgG4, and Or for <4 weeks Or impairment of daily activities,
T-helper 2 (Th2) cells, which secrete a restricted repertoire of leisure, and/or sport
cytokines, including interleukin-4 (IL-4), -5, -9, -10, and -13, Or impairment of school or work
which coordinate and activate other allergic effector cells, such Or troublesome symptoms
as innate lymphoid cells (ILCs). Persistent Moderate-Severe
The allergic airway diseases are typically chronic and occasion- Symptoms present for Presence of sleep disturbance
ally fatal; although spontaneous remissions are not uncommon, >4 days a week
the conditions are rarely curable. Recent insights into pathophysi- Or for >4 weeks And/or impairment of daily activities,
ological mechanisms have, however, opened up new prospects leisure, and/or sport
for improved therapy. And/or impairment of school or work
And/or troublesome symptoms
CLINICAL PRESENTATION OF ALLERGIC
AIRWAY DISEASE In contrast to rhinitis, which involves inflammation and
symptoms confined to the nasal passages and mucosa, rhinosi-
Although the diverse effector cells and molecules that characterize nusitis (RS) affects both the sinuses and the nasal mucosa.
allergic inflammatory exudates may be seen at any point along Rhinosinusitis can be subdivided into acute and chronic rhino-
the respiratory tract, the functional impact of allergic disease is sinusitis (CRS), based on duration of symptoms. CRS is reported
quite different in the upper and lower airways. to affect approximately 29 million Americans and is defined by
symptoms persisting for longer than 12 weeks. Clinically, CRS
Chronic Rhinitis and Rhinosinusitis is subdivided on the basis of the presence or absence of nasal
Epidemiology and Clinical Presentation polyps. Within CRS with nasal polyps (CRSwNP), there are
The major upper airway inflammatory disorders are rhinitis and several recognized clinical subtypes, including allergic fungal
chronic rhinosinusitis. Allergic rhinitis (AR) involves inflamma- rhinosinusitis (AFRS), aspirin-exacerbated respiratory disease
tion of the nasal mucosa: it is the most common type of chronic (AERD), and cystic fibrosis. 2
rhinitis affecting approximately 50 million Americans. In different Signs and symptoms associated with RS in adults include
surveys, AR accounts for 30–70% of chronic perennial rhinitis, facial pain and pressure, headaches, nasal congestion with or
with the balance being nonallergic. Typical symptoms of AR without obstruction, frontal or post nasal drainage, generalized

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