radioallergosorbent [RAST] testing

In vitro test measuring IgE to a specific allergen. In general it is more expressive & less sensitive than skin testing. Procedure: 1) allergen protein is chemically coupled to a solid-phase substance 2) patient serum is incubated with the solid support 3) the solid support is washed free on non-binding materials 4) the washed support is incubated with radiolabelled anti-IgE antibody 5) wells are counted (presumably various dilutions of patient serum) & compared against a standard curve prepared from known amounts of allergen-specific IgE Clinical significance: In general, in vitro RAST testing is not as sensitive as skin testing. It is useful in patients: 1) who have been taking antihistamines in whom no positive histamine responsiveness can be induced in the skin 2) with primary skin disorders that make allergen skin testing impractical (i.e., generalized eczema)

Specific

Coffee bean IgE Ab RAST class in serum Coffee IgE Ab RAST class in serum Japanese Cedar IgE Ab RAST class in serum Sweet Vernal grass IgE Ab RAST class in Serum

References

Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 84