The science

The cells

Blood plays many important roles in your body, but one of the most important is carrying oxygen around the body and removing waste. Your blood contains many different kinds of cells and interacts with many others.

Here are just a few that are relevant to PNH:

The defense network

The role of the immune system is to protect the body from dangers like disease and infection. It is a sophisticated defense network that keeps the body safe.

One very complex weapon in this arsenal is called “the complement system.” You may also hear it referred to as the “complement cascade.”

Complement’s job is to help destroy dangerous cells, like some viruses or bacteria, and to get rid of damaged or dying cells.

How it works

The complement system is an army of more than 50 different proteins that work together to get rid of dangerous cells and fight infection.

It does this through a complex system of connected reactions: one reaction leads to another and then another and another.

Think of these reactions like dominoes – one piece tips over, which starts a cascading reaction of other falling dominoes.

What happens in PNH

Normally, the cells in our body have their own natural shield to prevent the complement system from accidentally attacking them. In PNH, however, red blood cells are missing their natural protective proteins. The complement system attacks them, breaking them apart.

Another type is called “intravascular hemolysis,” which means red blood cells are destroyed inside the blood vessel.

One type of attack is called “extravascular hemolysis,” which means the red blood cells are destroyed in the liver and spleen.

Both types of hemolysis are responsible for the symptoms of PNH. When these red blood cells break apart, hemoglobin (the “glue” that sticks to oxygen and carries it around the body) is eliminated in urine. Low hemoglobin leads to low oxygen, which causes symptoms like fatiguefatigueExtreme tiredness or exhaustion. Fatigue is one of the most common symptoms of PNH., headache and shortness of breath, among others.

To stop the symptoms of PNH, we need to stop these attacks … or stop those dominoes from falling.

What happens in PNH

Normally, the cells in our body have their own natural shield to prevent the complement system from accidentally attacking them. In PNH, however, red blood cells are missing their natural protective proteins. The complement system attacks them, breaking them apart.

One type of attack is called “extravascular hemolysis,” which means the red blood cells are destroyed in the liver and spleen.

Another type is called “intravascular hemolysis,” which means red blood cells are destroyed inside the blood vessel.

Both types of hemolysis are responsible for the symptoms of PNH. When these red blood cells break apart, hemoglobin (the “glue” that sticks to oxygen and carries it around the body) is eliminated in urine. Low hemoglobin leads to low oxygen, which causes symptoms like fatiguefatigueExtreme tiredness or exhaustion. Fatigue is one of the most common symptoms of PNH., headache and shortness of breath, among others.

To stop the symptoms of PNH, we need to stop these attacks … or stop those dominoes from falling.

Learn more about detailed symptoms, diagnosis and treatment at the Aplastic Anemia and MDS International Foundation website.