Studies on the in vitro effects of auto-anti-IgE. Inhibition of total and specific serum IgE detection by a human IgG autoantibody to IgE.

We isolated a human IgG anti IgE autoantibody by affinity chromatography on a myelomatous IgE (N.D.) coated Sepharose column, from the serum of a patient with atopic eczema, and probed its ability to inhibit IgE recognition by heteroantisera to IgE used in commonly available assays for serum total and specific IgE determinations (Paper radio-immunosorbent test--PRIST and Phadezym radioallergosorbent test--RAST, both from Pharmacia, Uppsala--Sweden). Our results indicate that IgG anti IgE decrease total IgE results by 10-90% according to its weight ratio to IgE molecules present in samples devoid of endogeneous anti-IgE. Sera with high content of specific IgE to house dust mite (RAST class 3 or 4) are less affected by this autoantibody, but RAST class 2 may be significantly lowered when purified IgG anti IgE is added. These data imply that anti IgE can affect both total and specific IgE determinations.