Response of the rat mucosal and connective tissue type mast cells to interferon-alpha.

The distribution, density and histochemical subtype of mast cells (mucosal and connective tissue) were studied in the ileum, trachea and skin of rats treated with IFN alpha (70.000 IU/kg) treated rats. Light and electron microscopic procedures were utilized. The total number of mucosal mast cells in the sections of ileum and trachea were markedly increased in the IFN-alpha treated group (ileum: 31.9 +/- 2.2 cells/villuscrypt unit; trachea: 10,355 +/- 264 cells/mm3). However, the number of connective tissue mast cells did not show any significant change in the skin between IFN-alpha treated (1,472 +/- 125 cells/mm3) and saline-treated (1,757 +/- 264 cells/mm3) groups. We conclude that mast cell proliferation does exist in the rat ileum and trachea but no in the skin response to IFN-alpha. We suggest that this model provides a powerful tool to study differential effects of IFN-alpha on mast cell subtypes and to identify their role in the immunoregulatory and inflammatory reactions.