Immunological outcome measures.

Abstract

The determination of immunoglobulin E (IgE) antibodies by one of several laboratory tests, by skin-prick tests or by appropriate challenge procedures is useful either to identify atopic individuals or as outcome predictors in wheezy children. The determination of allergen specific antibodies of other isotypes, e.g. immunoglobulin G (IgG) and IgG subclass antibodies in serum, secretory immunoglobulin A (IgA) and various immune complexes, have not been confirmed as clinically useful tools for this purpose. Immune responses in atopic and nonatopic individuals differ in several other respects, e.g. they express somewhat different lymphocyte and cytokine profiles, as well as cellular immune responses. At present, none of these differences can be employed clinically, however, and the determinations are still research tools. A reduction in exposure to allergens is associated with fewer symptoms and improved lung function in sensitized individuals. There are also indications that reduced exposure to allergens in early infancy may prevent, or at least delay, sensitization and wheezing in atopic children. Determination of exposure to major indoor allergens, e.g. house dust mite, cat and cockroach allergens, are, therefore, of value in the assessment of the wheezing atopic infant. The relationship between wheezing disorders and the results of most immunological tests remain to be defined. In particular, the sensitivity, positive and negative predictive value and the diagnostic efficiency of recently introduced immunoassays remain to be defined. At present, there are no immunological tests of documented value to identify the severity of disease, or to predict the outcome of a certain therapy.