TNF-α Controls Intrahepatic T Cell Apoptosis and Peripheral T Cell Numbers

At the end of an immune response, activated lymphocyte populations contract, leaving only a small memory population. The deletion of CD8 + T cells from the periphery is associated with an accumulation of CD8 + T cells in the liver, resulting in both CD8 + T cell apoptosis and liver damage. After adoptive transfer and in vivo activation of TCR transgenic CD8 + T cells, an increased number of activated CD8 + T cells was observed in the lymph nodes, spleen, and liver of mice treated with anti-TNF-α. However, caspase activity was decreased only in CD8 + T cells in the liver, not in those in the lymphoid organs. These results indicate that TNF-α is responsible for inducing apoptosis in the liver and suggest that CD8 + T cells escaping this mechanism of deletion can recirculate into the periphery.