About 70 million Americans have high blood pressure — that's roughly 1 in 3 — and almost as many have prehypertension, according to the Centers for Disease Control and Prevention.

Even though the disease is widespread, scientists have never understood what causes high blood pressure, but Australian scientists have found the cause and how it could be reversed.

Researchers from the University of Monash's Biomedicine Discovery Institute found that stimulating the immune system can trigger hypertension, while calming the immune response can restore normal blood pressure levels.

Professor Grant Drummond says that B cells, which are a type of immune cell, produce too many antibodies in response to factors such as stress or consuming too much salt.

The antibodies settle in the blood vessels, causing them to become scarred and stiff, leading to hypertension.

But mice that were bred without mature B cells didn't develop high blood pressure.
In addition, when the activity of B cells was blocked in normal mice, their blood pressure returned to normal, basically curing their hypertension.

The new discovery could revolutionize the treatment of high blood pressure, and effective drugs to treat autoimmune diseases are already approved.

Using drugs that dampen immune response could also help patients with hypertension — up to 20 percent — that aren't helped by conventional drug therapies.

"These patients could benefit from strategies that target the immune system," said Drummond.

"Drugs such as Rituximab that target B cells are already used clinically for the treatment of rheumatoid arthritis and other autoimmune diseases.

"We think that these drugs could also be used to treat hypertension in the most serious of cases," he said.

Study results were published in the journal Hypertension.