Experimental induction of sialadenitis in rats by heterologous anti-salivary gland antibodies.

The purpose of the present study was to investigate the possibility of experimental induction of sialadenitis in rats by heterologous anti-salivary gland antibodies. Two fractions (Fraction I and II) were separated from rat submaxillary gland by Sephadex-G 200 gel-filtration, and then rabbits were immunized with each fraction. Although cross-reactivity of anti-FrI antiserum obtained from the rabbits against rat liver and rat serum was shown, specific reactivity of both anti-FrI and anti-FrII antisera against rat submaxillary gland was demonstrated by immunodiffusion or the indirect immunofluorescence method. Activity of antibody-dependent cell-mediated cytotoxicity against fresh rat submaxillary gland was also demonstrated using the anti-FrII antiserum in vitro. Sialadenitis with periductal cell infiltrations was induced in the submaxillary glands of many rats injected intraperitoneally with each heterologous antiserum. Similar lesions, however, were also induced in the parotid glands, livers, or kidneys of these rats. By a direct immunofluorescence method, granular deposits of rabbit gammaglobulin were detected in cytoplasma of the infiltrating cells and the small vessels around the lesions of the submaxillary glands. It was suggested, therefore, that the lesions are induced by circulating immune complexes probably formed by non-organspecific antibodies contaminating each antiserum. Salivary gland lesions induced by a similar mechanism were also suggested in patients with Sjögren's syndrome, although the pathological significance in vivo of the anti-salivary gland antibody as an organspecific antibody could not be confirmed by the present study.