Assessment of the effect of IgG antibodies to ragweed and rye grass on the IgE antibody disc RAST.

The results of the present study indicate that the IgE disc RAST is susceptible to interference by IgG antibodies directed against the same allergens on the disc. Thus removal of IgG antibodies with protein A-Sepharose caused an enhancement of as much as 66% in IgE RAST binding for six sera from treated ragweed and rye grass allergic patients. Furthermore, such interference was shown to vary for a given patient over a period of two years. The use of an alternate support media, matrex-beads linked with excess of ragweed allergen, eliminated the interference effect. The relationship between IgG antibody levels and the interference effect as well as the clinical significance of these findings is discussed.