Immunocompetence of the guinea pig's middle ear

Immunocompetence of the middle ear was studied in guinea pigs in two series of experiments. The first, afferent phase, consisted of grafting iso and allografts in the guinea pig's middle ear to sensitize the animals which were later to receive a skin graft on the back. The second, efferent phase, first sensitized the animals with a skin graft on their back and later in the middle ear. The results show a rather low capacity of the middle ear to elicit a second-set rejection of the skin grafts. This lack of sensitization is explained by the authors by the concept of tolerance.