Circulating human IgG autoanti-IgE antibodies

Aims-To investigate the ability of circulating human IgG autoanti-IgE antibodies from asthma patients to block the binding of IgE to the a chain of the high affinity receptor (FcERI). Methods-This involved the use of a well validated flow cytometric method to detect inhibition ofFITC labelled IgE binding to a fibroblast cell line (CHKIEl) transfected with the a chain of FcERI. Results-IgG autoanti-IgE-containing sera blocked the binding of IgE-FITC to the CHKlEl cells. No such inhibition was demonstrable with rheumatoid sera containing autoanti-IgG (that is, rheumatoid factor) but lacking autoanti-IgE. Percentage inhibition (up to 50%) ofIgE binding to the CHKlE1 cells was directly related to the titre of IgGl, but not IgG4, autoanti-IgE in the sera tested (correlation coefficient 0-66, probability 0.003). Conclusions-The capacity of anti-IgE to block the binding of IgE to FcERI has important clinical implications, particularly in terms of downregulation of allergic reactions. (J Clin Pathol: Mol Pathol 1995;48:Ml48-M152)