Protein C

Protein C is a protein that in humans is encoded by the PROC gene. Protein C is a major physiological anticoagulant. It is a vitamin K-dependent serine protease enzyme (EC 3.4.21.69) that is activated by thrombin into activated protein C (APC). The activated form (with protein S and phospholipid as a cofactor) degrades Factor Va and Factor VIIIa. It should not be confused with C peptide or c-reactive protein or protein kinase C.

Autoimmune Disease

Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells.The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to certain organs (e.g. in thyroiditis) or involve a particular tissue in different places (e.g. Goodpasture’s disease which may affect the basement membrane in both the lung and the kidney). The treatment of autoimmune diseases is typically with immunosuppression—medication which decreases the immune response.

There is an on-going discussion about when a disease should be considered autoimmune, leading to different criteria such as Witebsky’s postulates.