What are GPA and MPA?

Granulomatosis with Polyangiitis (GPA) and Microscopic Polyangiitis (MPA) are two types of ANCA-associated vasculitis, or AAV. AAV is a form of vasculitis that primarily affects the small blood vessels in your body. In general, GPA and MPA affect the sinuses, kidneys, lungs, and skin, but the way the diseases show themselves varies.

About AAV

AAV causes inflammation in the small blood vessels. This inflammation causes the layers of the blood vessel wall to thicken, which narrows the blood vessel and reduces the amount of blood that can flow through it. This reduction in blood flow can cause serious problems and even damage the body's organs.

The role ANCAs play in AAV

AAV is a type of inflammation associated with autoantibodies (pronounced aw-toh-AN-ti-bod-ees). Regular antibodies exist in the blood and are produced by the immune system to fight germs. An autoantibody is an antibody that acts against the body's own tissues and cells. The autoantibody involved in AAV is called ANCA. That's why the disease itself is called ANCA-associated vasculitis. ANCAs lead to inflammation that targets and attacks the blood vessel walls in different tissues and organs in the body.

ANCAs are usually present in AAV, but there are times when this is not the case. Your doctor will perform a blood test to look for ANCAs.

Marked by periods of flares and remission

In GPA and MPA, there are periods of flares and periods of remission. Flares occur when your symptoms worsen or new symptoms appear. Remission, on the other hand, is a long or short period of time after a flare when symptoms are controlled or go away. It's a time when the disease is considered quiet.

Since GPA and MPA are chronic diseases, they never completely go away. So even when you are in remission, your doctor may prescribe other therapies to control your disease. Keep in mind that everyone's experience is different, so it's hard to predict when a flare may occur.