Experimental otitis media in chinchillas. I. Baseline immunological investigation

Baseline immunological data on the chinchilla were obtained, and a detailed method for purification of each immunoglobulin is described. Antiserum to each chinchilla immunoglobulin was made by immunizing rabbits with immunoglobulins purified from serum and colostrum. The main classes of serum immunoglobulins in the chinchilla are G, A, and M, similar to those in other rodents and humans. The immunohistochemical study showed that the distribution of immunocytes in lymphoid organs is similar to that of other rodents and humans. In the eustachian tube the glandular acinar cells were distinctly positive for IgA staining. A few IgA-forming cells and very rare IgG- and IgM-forming cells were found in the eustachian tube mucosa, but all were very rare in the middle ear mucosa. These findings suggest that the secretory immune system of the chinchilla eustachian tube may be active in the normal state and that the local immune system of the normal middle ear mucosa may be latent but could become active following antigenic stimulation.