Atopy and Antiallergic Therapy

Atopy denotes a hereditary predisposition for IgE-mediated allergic reactions. Clinical pictures include allergic rhinoconjunctivitis ( hay fever ), bronchial asthma, atopic dermatitis (neurodermatitis, atopic eczema) and urticaria. Evidently, differentiation ofT-helper (TH) lymphocytes toward the TH2 phenotype is the common denominator. Therapeutic interventions are aimed at different levels to influence pathophysiological events (A). 

Specific immune therapy ( hyposensitization ) with intracutaneous antigen injections is intended to shift TH cells in the direction ofTH,. 

Inactivation of IgE can be achieved by means of the monoclonal antibody, omalizu-mab. This is directed against the Fc portion of IgE and prevents its binding to mast cells. 

Stabilization of mast cells. Cromolyn prevents IgE-mediated release of mast cell mediators, although only after chronic treatment. It is applied locally to conjunctiva, nasal mucosa, the bronchial tree (inhalation), and intestinal mucosa (absorption is almost nil with oral intake). Indications prophylaxis of hay-fever, allergic asthma, and food allergies. Nedocromil acts similarly. 

Blockade of histamine receptors. Allergic reactions are predominantly mediated by H, receptors. Hj-antihistaminics (p. 118) are mostly used orally. Their therapeutic effect is often disappointing. Indications allergic rhinitis (hay fever). 

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