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radioallergosorbent test n a radioimmunoassay for specific antibodies of immunoglobulin class IgE in which an insoluble matrix containing allergenic antigens is reacted with a sample of antibody-containing serum and then reacted again with antihuman antibodies against individual IgE antibodies to make specific determinations abbr. RAST
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(RAST) (for measurement of IgE antibodies in serum) allergen extract is coupled to a solid matrix (paper, cellulose particles); this immunosorbent is reacted with serum and washed and then reacted with radiolabeled anti–human IgE antibody and washed. Uptake of the labeled antibody is proportional to the level of specific serum IgE antibodies to the allergen. This test may be used as an alternative to skin tests to determine sensitivity to suspected allergens.Medical dictionary. 2011.