CIRCULATING HUMAN-IGG AUTOANTI-IGE ANTIBODIES IN ASTHMA PATIENTS BLOCK THE BINDING OF IGE TO ITS HIGH-AFFINITY RECEPTOR

Aims-To investigate the ability of circulating human IgG autoanti-IgE antibodies from asthma patients to block the binding of IgE to the alp ha chain of the high affinity receptor (Fc epsilon RI). Methods-This i nvolved the use of a well validated flow cytometric method to detect i nhibition of FITC labelled IgE binding to a fibroblast cell line (CHK1 E1) transfected with the alpha chain of Fc epsilon RI. Results-IgG aut oanti-IgE-containing sera blocked the binding of IgE-FITC to the CHK1E 1 cells. No such inhibition was demonstrable with rheumatoid sera cont aining autoanti-IgG (that is, rheumatoid factor) but lacking autoanti- IgE. Percentage inhibition (up to 50%) of IgE binding to the CHK1E1 ce lls was directly related to the titre of IgG1, but not IgG4, autoanti- IgE in the sera tested (correlation coefficient 0.66, probability 0.00 3). Conclusions-The capacity of anti-IgE to block the binding of IgE t o Fc epsilon RI has important clinical implications, particularly in t erms of downregulation of allergic reactions.