Although oral administration of protein antigens may lead to specific immunologic unresponsiveness, this method of immunoregulation has not been applied to models of autoimmune disease. Type II collagen-induced arthritis is an animal model of polyarthritis induced in susceptible mice and rats by immunization with type II collagen, a major component of cartilage. Intragastric administration of soluble type II collagen, prior to immunization with type II collagen in adjuvant, suppresses the incidence of collagen-induced arthritis. Administration of denatured type II collagen has no observable effect on the incidence or severity of the disease. The overall magnitude of the antibody response is not significantly reduced in collagen-fed mice as compared to controls. While the isotype distribution of the anti-collagen antibodies is similar in the two groups, there is a tendency toward reduced IgG2 responses in the collagen-fed mice.Type II collagen-induced arthritis (CIA) is an animal model of polyarthritis induced in susceptible mice and rats by immunization with type II collagen (1, 2). Type II collagen is the major matrix protein of hyaline cartilage. The similarity of the histopathologic changes observed in CIA to those seen in human rheumatoid arthritis has centered interest on the contribution of collagen autoimmunity to the pathogenesis of the human disease. Although humoral and cellular immunity to type II collagen have been shown in CIA, the precise contribution of each to the development of disease has not been established. While T cells have been shown to recognize undenatured and denatured type II collagen (3), the humoral response is restricted to the undenatured, nonrepeating helical antigenic determinants of the collagen molecule (3, 4

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Wattle responses of 2-to-8-week-old chickens to phytohemagglutinins PHA-P and PHA-M were studied. Dilutions of PHA-M that did not induce wattle swelling after one injection did cause readily detectable swelling when injected a second time 1 week later. These responses were absent in birds subjected to thymectomy and gamma-irradiation at hatching and in birds treated with cyclosporin A during the week of sensitization, indicating that these responses are T-cell-dependent. Chickens bearing transplantable fibrosarcomas failed to show responses. It is suggested that reactivity to a second injection of PHA-M may be used as a measure of immunocompetence at the T-cell level in very young chickens.

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