Immunoglobulin G- and immunoglobulin E-mediated airway smooth muscle contraction in the guinea-pig

Guinea-pig antibody to ovalbumin was separated into two pools using Protein A Sepharose. The antibody pool retained by the Protein A Sepharose [immunoglobulin (Ig) G pool] was heat stable and persisted in skin sites of the guinea pig less than 7 days. The antibody pool which did not bind to Protein A Sepharose (IgE pool) was heat labile and persisted in guinea-pig skin at least 10 days. Both antibody pools were capable of mediating contraction of isolated guinea-pig tracheal and lung parenchymal strips using airway strips passively sensitized in vivo or in vitro. Although the majority of the skin sensitizing ability of the IgE pool was destroyed by heating at 56° C for 4 hr, its ability to mediate airway contraction was only partially inhibited. Experiments examining [¹²⁵I]Protein A binding of the antibody pools indicated that the contraction seen in airways sensitized with IgE pool was not due to contamination of IgG. These studies provide a system for examining antagonism of and mediators responsible for IgG-vs. IgE-mediated airway contraction and for evaluating the apparently heat stable properties of IgE.