[Pathogenesis of spontaneous hepatitis in an inbred strain of LEC (Long Evans cinnamon) rats].

We have reported an inbred strain LEC rats with high frequency of spontaneous hepatitis. In this paper, we study a possible involvement of hepatitis virus, hereditary background, and correlation between serum IgG level and onset of hepatitis in LEC rats. Neither electron microscopy nor indirect immunofluorescent test could detect hepatitis virus article or antigen. Furthermore, we could not succeed in inducing hepatitis of LEA and WKA/H rats by injecting the serum, plasma and liver homogenates of the affected IEC rats, nor in promoting/developing hepatitis of LEC and LEA rats under the immunosuppressed condition by administration of steroid hormone. When we made a mating between LEC and non-hepatitis rats to investigate the hereditary mode, F1s had no hepatitis, but F2s and backcrosses developed hepatitis. We observed, in particular, the lower the serum IgG level was, the higher the rate of developing hepatitis was. From these results, we speculate that the involvement of hepatitis virus is not likely, but that a genetic mutation might cause low level of IgG and be also correlated with development of hepatitis.