[Allergen skin tests. Asthmatic infants and young children]

Skin tests represent a major tool in the diagnosis of IgE mediated-allergy. The main indication is the measure of atopy during infancy and early childhood, as a predictive factor of the development of asthma. When atopic eczema is present, skin testing can provide a diagnosis of food allergy. Skin tests are easily done, without absolute contraindications. The epidemiological knowledge helps to choose the allergens to test. The skin-prick test method is well standardized and must be rigorous because of the hyporeactivity of the infant skin. Results are always confounded with positive and negative control solutions. The interpretation of pricks tests must be careful, standing out a clinical allergy (when clinical allergic symptoms are presents) from a sensitization (atopy). The predictive value of a positive skin test is discussed: predisposition to asthma, association with severe asthma, predisposition to acute bronchiolitis during an epidemic of respiratory virus. A positive skin test to food allergen would predict a later pneumallergen sensitization.