New York, Nov 18 (IANS): An international team of researchers has identified the second protein that turns a person's immune system against itself in the form of a kidney disease known as membranous nephropathy (MN).

Membranous nephropathy occurs when the small blood vessels in the kidney that filter wastes from the blood are damaged by circulating auto-antibodies.

As a result, proteins leak from the damaged blood vessels into the urine. For many people, loss of these proteins eventually causes symptoms of nephrotic syndrome.

This is the second protein associated with MN and the development of an autoimmune response. Through the identification of this second protein, a new blood test can be developed to diagnose and monitor this common form of kidney disease.

Unchecked, MN can lead to kidney failure or end stage renal disease.

"Five years ago, this team initially discovered a protein that led to a blood test identifying between 70 and 80 percent of people with MN," said Jon Klein, MD, from the University of Louisville in Kentucky.

"We now have found another protein that impacts up to another five percent of patients with MN. Once a blood test is available, we will have been able to reduce the number of kidney biopsies necessary for disease detection and to assess the response to treatment by up to 85 percent," Klein added.

The findings were published online in the New England Journal of Medicine.