Question

What are some of the differences in the manifestations of diseases caused by antibodies against extracellular matrix proteins and by immune complexes that deposit in tissues?

Answer 1

Extracellular matrix refers to the network of non-cellular entities such as enzymes, collagen, and glycoproteins that aids the cells biochemically as well as structurally. The major proteins present in the extracellular matrix are collagen and elastin. When the body produces antibodies against the extracellular matrix, it is termed as autoimmunity as these proteins are self-proteins. This type of immunity is categorized under hypersensitivity type II. The antibodies involved in such types of autoimmunity are IgG or IgM. Collagen vascular disease is an example of such type of autoimmune disease which causes inflammation in collagen and the joints present near it.

The immune complex is said to the structure formed by the binding of antigen and antibodies. It is a fundamental action of antibodies. After which the complex undergoes complement deposition, opsonization, and phagocytosis. However, in some cases, the immune complex is deposited in the organs or tissues that lead to inflammation. This type of autoimmunity is categorized under type III hypersensitivity. Some forms of vasculitis are an example of this kind of disease which affects arteries as well as veins.