population, more research is needed to determine the predictive values of both skin prick and intradermal tests. Moreover, the doses and criteria for positive skin tests used for such studies need further definition, together with criteria to define the relationship of a positive skin prick test to the wheal area or erythema that appears.
Recommendation: Encourage the development and use of improved standardized methods for performing and interpreting skin tests.
For safety reasons, appropriately trained personnel and adequate equipment need to be available to treat possible adverse systemic reactions.
Confirmation of the diagnosis of an allergic reaction resulting from a given agent generally requires some immunologic test that demonstrates a specific antibody response to the agent. For allergic rhinoconjunctivitis and most allergic asthma, demonstration in vivo or in vitro of specific IgE would be appropriate. For hypersensitivity pneumonitis, in vitro demonstration of either specific immunoglobulin or specific cell-mediated immunity, or both, would be acceptable. Although allergic asthma is IgE mediated, the immunopathogenesis of non-IgE-mediated asthma has not been elucidated; thus, the appropriate corroborative immunologic tests are unknown. The exact role of cell-mediated immunity and T cell activation in asthma also has not been defined. Therefore, the role of assays to detect specific cell-mediated immunity or T cell activation in asthma is unclear.
An immunologic response to an agent is not sufficient to diagnose an allergic disease caused by that agent. Such a response means only that a prior sensitizing exposure to the agent or a cross-reacting agent has occurred. Diagnosis of a hypersensitivity disease such as allergic rhinitis requires a compatible clinical syndrome in addition to the appropriate specific immunologic response.
Several in vitro tests are available for use in clinical practice and research. These include a variety of serum antibody tests and tests of cell-mediated immunity. These tests are discussed below, along with the importance of reagent quality, the diagnostic value of the tests, and the importance of quality control.
Several investigators have reported on in vitro tests for estimating IgE directed against an allergen. A widely used immunoassay is the RAST, in which the allergen is bound to a solid phase and then incubated first with patient serum and then with radiolabeled antihuman IgE (Adkinson, 1986).