VII. Drug Allergy

A.Definition. Reactions to drugs are mediated by IgE or by direct mast cell degranulation (also known as “anaphylactoid”).

B.Etiology. Many pharmaceutical agents have been documented to cause allergic reactions or anaphylaxis. The most common offending agents include penicillin, sulfonamides, cephalosporins, aspirin and other nonsteroidal anti-inflammatory drugs, and narcotics.

C.Clinical features include urticaria, angioedema, and anaphylaxis. (Angioedema is a vascular reaction of the deep dermis or subcutaneous tissue, associated with localized edema from dilated capillaries with increased permeability, and characterized by giant wheals.)

D.Diagnosis is made by clinical features and history of drug ingestion.

E.Management

1.Antihistamines may be effective.

2.Anaphylaxis should be treated as described in section I.E.

3.Medical alert bracelets should be worn by patients with previously identified significant drug reactions.

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VIII. Asthma

Asthma (see , section IV.A) may be precipitated by an allergic cause in some patients.

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IX. Immunology Overview

A.Main components of the immune system. The immune system is a complex organization of cells and molecules that serves to protect the host from infection. The components of the immune system can be divided functionally into innate and adaptive components.

1.Innate responses are the first defense against infection. The cells and molecules of the innate system include phagocytic cells, natural killer cells, toll-like receptors, mannosebinding protein, and the alternative pathway of complement.

2.Adaptive responses develop more slowly, are highly specific, and improve with repeated exposure to an antigen. The adaptive system includes T cells, B cells, and immunoglobulin molecules.

B.Immunodeficiency states may be primary or secondary (Table 15-3).

C.In the evaluation of a patient with a suspected immunodeficiency, there are a variety of diagnostic tests used to identify the type of primary immunodeficiency state (Table 15-4).

Table 15-3

Categories of Immunodeficiency States

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Neisseria species

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