In vitro tests for immediate hypersensitivity.

In vitro measurement of IgE antibodies in serum has an established role in the study of allergic disease, but the place of in vitro tests in routine diagnosis is not well established. They are particularly helpful in confirming new allergens in the workplace and in situations where skin testing is potentially dangerous or technically not feasible. The basic procedure is the radioallergosorbent test (RAST). Each modification has its peculiar advantages and disadvantages. A clinician depending upon in vitro tests for diagnosis must be aware of the technical problems, the inherent limitation in sensitivity in comparison to skin testing, and above all, the fact that in vitro tests detect the presence of an IgE antibody in serum but give no direct information about its pathogenetic role in an individual patient.