THE IMMUNOLOGICAL MILIEU OF THE LIVER IN HEALTH AND DISEASE

Abstract

The liver, which is one of the largest organs of the body, has many complex functions. One of these important functions is its immunological role, which significantly affects the immune system of the body in health and disease. The immunological function of the liver starts since fetal development, when the lymphocyte precursors become transformed into the lymphocytes responsible for humoral immunity. The liver is the principal site for destruction ofT-cells during activation-induced cell death. This explains why the liver allografts can be established with little or no immunosuppression, and without precise MHC matching between donor and host, as the entry and deletion of successive waves of allospecific CD8+ cells would deplete the peripheral T-cell pool, resulting in allospecific systemic tolerance. The liver parenchyma contains Kupffer cells, which are derived from monocytes. It constitutes the largest single mass of mononucleur phagocytes in the body and accounts for about 80% of the phagocytic capacity of this system. They phagocytose damaged and ageing red blood cells, bacteria, viruses, antigen­ antibody complexes and endotoxin and produce numerous substances involved in inflammatory and immune reactions. They also take up antigenic material, but unlike macrophages elsewhere in the body, they do not produce processed antigen and thus prevent antigen from eliciting immunological responses.