Latex allergosorbent test (LAST): A new immunoassay for specific IgE with latex particles

We describe a two-step latex (Lx) agglutination assay for the titration of specific anti- Dermatophagoides pteronyssinus IgE. The samples are first incubated with allergen-coated Lx of 2.3 μm diameter. Bound IgE is digested by pepsin and then titrated by its agglutinating activity on 0.8 μm Lx particles coated with antihuman Fc ϵ rabbit F(ab′) 2. This latex allergosorbent test detects 100 pg of specific IgE per milliliter and does not depend on the concentration of total IgE. Owing to a tenfold increase in the allergosorbent surface, no competition with the binding of specific anti- D. pteronyssinus IgG is observed. Pepsin digestion eliminates potential interferences caused by autoantibodies against IgE. A good correlation (r = 0.92) is found with Phadebas RAST on a series of 91 samples. The latex allergosorbent test does not make use of radioisotopes and can be performed in