Abstract
The interaction of IgE with its high-affinity Fc receptor (Fc epsilon RI) followed by an antigenic challenge is the principal pathway in IgE mediated allergic reactions. As a consequence of the high affinity binding between IgE and Fc epsilon RI, along with the continuous production of IgE by B cells, allergies usually persist throughout life, with currently no permanent cure available. Horses, especially race horses, which are commonly inbred, are a species of mammals that are very prone to the development of hypersensitivity responses, which can seriously affect their performance. Physiological responses to allergic sensitization in horses mirror that observed in humans and dogs. In this paper we describe the development of an in situ assay system for the quantitative assessment of the release of mediators of the allergic response pertaining to the equine system. To this end, the gene encoding equine Fc epsilon RI alpha was transfected into and expressed onto the surface of parental Rat Basophil Leukemia (RBL-2H3.1) cells. The gene product of the transfected equine alpha-chain formed a functional receptor complex with the endogenous rat beta- and gamma-chains (1). The resultant assay system facilitated an assessment of the quantity of mediator secreted from equine Fc epsilon RI alpha transfected RBL-2H3.1 cells following sensitization with equine IgE and antigenic challenge using beta-hexosaminidase release as a readout (2, 3). Mediator release peaked at 36.68% +/- 4.88% at 100 ng ml(-1) of antigen. This assay was modified from previous assays used to study human and canine allergic responses (4, 5). We have also shown that this type of assay system has multiple applications for the development of diagnostic tools and the safety assessment of potential therapeutic intervention strategies in allergic disease (6, 2, 3).