Extrinsic asthma

Illustrated in Figure 3 is a likely over-all mechanistic role of theophylline in asthma. Extrinsic or immediate hypersensitivity-type asthma begins with an antigen -antibody complex at mast cells and results in the release of chemical mediators which affect cells in airways. Smooth muscle cells contract, capillaries leak, and secretory cells hypersecrete to give a triad of bronchospasm, edema and Increased mucous, respectively. Shown is the two-enzyme... 

Intrinsic asthma, also called idiopathic asthma, usually develops in adulthood. In intrinsic asthma allergic factors are not demonstrable. Episodes of intrinsic asthma may be triggered by a variety of stimuli, eg, emotional state, exposure to cold air, or inert dusts. Both intrinsic and extrinsic asthmatics can be prone to exercise-induced attacks. Individuals who experience a combination of extrinsic and intrinsic asthmatic reactions have mixed asthma. Status asthmaticus refers to an especially acute life-threatening asthma attack which is resistant to normal treatments and which may require hospitalization in order to stabilize the patient. 

About 90% of all asthmatics have increased serum IgE levels and suffer from Type I allergy, called extrinsic (allergic) asthma. 

Extrinsic (also referred to as allergic asthma and caused in response to an allergen such as pollen, dust, and animal dander)... 

Mixed asthma (caused by both intrinsic and extrinsic factors)... 

RESPIRATORY SENSITIZER A substance that may cause sensitization on inhalation, causing, e.g., asthma, rhinitis or extrinsic allergic alveolitis. 

Jones et al. (49) also point to a possible connection between atopy and risk of byssinosis. Most but not all persons with extrinsic asthma exhibit atopy (50). From observations on 255 workers in four cottonseed crushing mills, Jones et al. (49) conclude that "Atopy and exposure to dust were found to have significant interaction large mean declines in FEVi and FEF25-75 occurred only in the workers exposed to 1 inter dust who were also atopic." They also state "These findings point to atopy as a risk factor in the bronchoconstrictor response to cotton dust aerosol, and, by inference, a risk in byssinosis. 

Reduction of allergen-induced inflammatory reactions in patients with extrinsic asthma 0.15 mg for 3 days... 

An aberrant immune response associated with allergy appears to underlie asthma in most children over age 3 years and in most young adults allergy-induced asthma is also known as extrinsic asthma. In contrast, a large number of patients, especially those who acquire asthma as older adults, have no discernible immunological basis for their condition, although airway inflammation remains a characteristic of the disease this type of... 

When taken regularly (2-4 puffs two to four times daily) by patients with perennial (nonseasonal) asthma, both agents modestly but significantly reduce symptomatic severity and the need for bronchodilator medications. These drugs are neither as potent nor as predictably effective as inhaled corticosteroids. In general, young patients with extrinsic asthma are most likely to respond favorably. At present, the only way of determining whether a patient will respond is by a therapeutic trial for 4 weeks. The addition of nedocromil to a standard dose of an inhaled corticosteroid appears to improve asthma control. 

Buckle FG, Cohen AB Nasal mucosal hyperpermeability to macromolecules in atopic rhinitis and extrinsic asthma. J Allergy Clin Immunol 1975 55 213-221. 

Besides respiratory allergies with hay-fever-like symptoms and asthma in atopic individuals, continuous occupational basidiospore exposure may result in hypersensitivity pneumonitis or extrinsic allergic alveolitis. The basidiomycetes Lentinus edodes, Pleurotus ostreatus, and Merulius lacrymans have all been shown to cause hypersensitivity pneumonitis from occupational exposure [26-28]. Actinomycetes in the compost used to grow button mushroom... 

O Brien IM, Bull J, Creamer B, Sepulveda R, Harries M, Bulge PS, Pepys J Asthma and extrinsic allergic alveolitis due to Merulius lacrymans. Clin Allergy 1978 8 535-542. 

Sodium cromoglicate is effective in extrinsic (allergic) asthma including asthma in children, and in exercise-induced asthma but its use has declined since the efficacy and safety of low dose inhaled corticosteroid have become apparent. 

A 37-year-old woman with a 5-year history of multiple itchy nodules on the outer aspects of the upper parts of the arms at sites of previous vaccine injections had been receiving hyposensitization vaccines to treat recurrent extrinsic asthma and rhinitis for 10 years (56). Physical examination and a biopsy of one of the nodules were identical to those of the previous case. Patch tests with aluminium chloride were negative. Symptomatic relief was obtained with topical corticosteroids and oral antihistamines. The nodules persisted for at least 3 years. 

The benefit to harm balance in desensitization treatment was examined in a meta-analysis published in 1995, covering 20 randomized, placebo-controlled, doubleblind trials of allergen immunotherapy for asthma. Systemic reactions occurred in a mean of 32% (20-44%) of patients, but anaphylaxis was reported on only four occasions. It was concluded that immunotherapy was a treatment option in highly selected patients with extrinsic allergic asthma where a clinically relevant and unavoidable allergen is identified (7). 

Acute asthma is a reactive airway disease (RAD) occurring when extrinsic (environmental) or intrinsic (internal) allergens stimulate bronchoconstriction, causing bronchospasms that result in wheezing and difficulty breathing. 

Sibbald B, Turner-Warwick M Factors influencing the prevalence of asthma among first degree relatives of extrinsic and intrinsic asthmatics. Thorax 1979 34 332-337. (Ill)... 

Examples of these pathophysiologic and pharmacodynamic differences are numerous. Clinical presentation of chronic asthma differs in children and adults. Children present almost exclusively with a reversible extrinsic type of asthma, whereas adults have nonspecific, nonatopic bronchial irritability. This explains the value of adjunctive hyposensitization therapy in the management of pediatric patients with extrinsic asthma. ... 

Humbert M, Menz G, Ying S, Corrigan CJ, Robinson DS, Durham SR, Kay AB The immunopathology of extrinsic (atopic) and intrinsic (non-atopic) asthma more similarities than differences. Immunol Today 1999 20 528-533. 

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