The role of complement system in haematosis and thrombosis

Complement is a system of plasma proteins that has important roles in the innate and adaptive immune responses. It is closely related to the coagulation system and the two are interconnected. There are three different pathways of complement activation, the classical, lectin and alternative pathways. The lectin pathway is activated when a multi-molecular activation complex binds to carbohydrate structures on microorganisms, or aberrant glycocalyx patterns on apoptotic, necrotic, or malignant cells. Lectin pathway activation complexes comprise a carbohydrate recognition molecule (mannan-binding lectin [MBL], collectin 11, or a ficolin) and MBL-associated serine proteases (MASP-1, -2 and -3). It has been reported that MBL-MASP complexes have a role in clot formation; MASP-1 activating fibrinogen and factor XIII, and MASP-2 activating prothrombin. Clots are generated when classified plasma is incubated with Ficolin-MASP and MBL-MASP complexes. The aim of this project was to study role of the MASPs in fibrin clot formation and to identify where the lectin pathway intercepts the coagulation system. A turbidimetric clotting assay was developed.