Inhibition of the Prausnitz–Küstner reaction by an immunoglobulin ε-chain fragment synthesized in E. coli

Abstract

The Prausnitz–Küstner (P–K) reaction is a sensitive test for the presence and activity in the skin of immunoglobulin E, an important class of immunoglobulin mediating allergic reactions. A fragment of the human myeloma ND ε-chain gene, encoding the second, third and fourth domains of the IgE constant region (Cε2–4) was assessed here for its ability to inhibit the P–K reaction in vivo. Injection of the fragment in skin sites of healthy human adults prevented subsequent sensitization with serum containing IgE antibody to ragweed antigen. Inhibition of the P–K reaction required a 200-fold molar excess of the C_ε fragment over the IgE present in the sensitizing serum. The efficacy of the C_ε fragment in inhibiting the P–K reaction compared favourably with that of natural myeloma IgE (PS) in terms of both blocking concentrations and duration of the blocking effect. The inhibition of the P–K reaction by C_ε2–4 fragments was specific and probably caused by the saturation of IgE receptors on mast cells^1,2 by the recombinant gene product.