Autoimmunity in trypanosome infections—II. Anti-fibrin/fibrinogen (anti-F) autoantibody in Trypanosoma (Trypanozoon) brucei infections of the rabbit

Rabbits infected with two strains of T. (T.) brucei showed an increase in the levels of a naturally occurring serum autoantibody directed against a component of the fibrin/fibrinogen system. This anti-F autoantibody is IgM throughout the infection. Absorption studies suggest that it reacts with one or more hidden determinants which are exposed after attachment of several species of fibrinogen molecule to red cell membranes. Absorption with autologous fibrin suggest the presence of the same determinant on the fibrin matrix after polymerisation of fibrinogen by thrombin. The antibody does not appear to react with fibrinogen in the circulation.

There is no evidence that this autoantibody causes any direct pathological change in the rabbit although secondary effects may be important. The antibody may have a beneficial effect by forming complexes with any fibrin deposited in tissues thereby enhancing its phagocytosis and rapid removal from the circulatory system.