Effect of neonatal thymectomy on experimental autoimmune hepatitis in mice

Using an autoimmune hepatitis model of A/J mice which was prepared with immunization by syngeneic crude liver proteins, various influences of neonatal thymectomy were studied by observations of histological liver changes, autoantibody to liver-specific membrane lipoprotein (LSP), delayed-type hypersensitivity (DTH) to LSP, and purified protein derivative (PPD), and suppressor activity to LSP. The liver changes in the thymectomized mice were more intense than those in the non-thymectomized controls. Production of the anti-LSP autoantibodies and positive DTH to syngeneic LSP could be recognized in both groups of the thymectomized mice and the non-thymectomized controls, but the levels of those were higher in the former. In the level of DTH to PPD the thymectomized mice were lower than the non-thymectomized controls. Adoptive transfer experiments showed that suppressor activity to LSP was reduced in the spleen cells of neonatally thymectomized mice. This experiment suggests that neonatal thymectomy is apt to abolish tolerance to LSP on account of depressed suppressor activity to autoantigen, and accordingly liver damage is increased.