Influencia del nivel de IgE sobre la actividad secretora del mastocito cutáneo en los procesos alérgicos en el perro

Abstract

Canine atopic dermatitis is a chronic imflammatory and pruritic skin disease characterized by an increase in the concentration of allergen specific IgE in the serum of the patients. Skin mast cells play an important role in the pathogenesis of this disease. The binding of IgE to the IgE-high affinity receptor (Fc?RI) on mast cells membrane, and its subsequent crosslinking by an allergen, is the first step in the cascade of reactions leading to the release of MC proinflammatory mediators, in part responsible for the development of the disease. In addition to its crucial role in mast cell activation, IgE has been shown to regulate the Fc?RI expression on human and murine mast cell surface. An increase in the concentration of IgE can, therefore, lead to an overexpression of the Fc?RI receptors, causing an increase in the mediators released by the sensitized mast cells, that can contribute to the development of the allergic process. Although dogs suffer with a high incidence allergic processes, this phenomenon mediated by IgE had not been studied in this specie yet. The main goal of the present study was to analyze whether an increase in the IgE concentration of canine mast cell microenvironment can influence the mast cells mediators release (histamine and TNF-?? through an IgE-dependent stimulation. This study was carried out in 3 phases: - The first part consisted in setting up the technique to sensitize and activate mast cells through the Fc?RI receptor, and to measure the different mediators(histamine and TNF-?) released by these cells. - We then investigated new methods to maintain viable mast cells in vitro. For this purpose, cells were cultured with Stem Cell Factor (SCF) an specific mast cell growth factor. We also investigated the usefulness of a mastocytoma cell line (C2) as an alternative cell source to perform the experiments. - Finally, we analyzed whether the addition of IgE serum in the culture medium may influence mast cells histamine release and TNF-? production after an IgE-dependent stimulation, and also the Fc?RI expresión in mast cell membrane. The main results of the present study are the following: - Cutaneous mast cells are able to release histamine and synthesize TNF-? after an IgE mediated activation. - Cutaneous mast cells can be maintained in vitro by the addition of SCF to the cellular culture medium, maintaining its secretory activity. - The co-stimulation of mast cells with SCF and anti-IgE significantly potentiates the release of histamine and TNF??. - The in vitro exposure of skin mast cells to increased serum IgE concentrations enhances their ability to release TNF-??upon immunological stimulation. - The significant increase in the number of Fc?RI positive cells (MC) cultured with IgE-rich serum may reflect an up-regulation of the Fc?RI on the surface of these cells.