
An innovative tool that uses a simple blood test can now distinguish and diagnose sarcoidosis, a chronic inflammatory disease marked by the growth of granulomas in the lungs and other organs in the body. A research project carried out by the National Institutes of Health (NIH) developed the tool, which will make diagnosis of this condition more efficient and economical. Previous diagnostic tests used to identify sarcoidosis were invasive and expensive. The research team recently published its findings in the American Journal of Respiratory and Critical Care Medicine.
“Currently, diagnosing sarcoidosis isn’t a straightforward process, and requires tissue removal and testing with additional screenings to rule out other diseases, such as tuberculosis or lung cancer,” said James Kiley, PhD, director of the Division of Lung Diseases at the National Heart, Lung, and Blood Institute, part of NIH. “Using a blood test will help diagnose faster, particularly in those organs that are more challenging to biopsy and with less harm to the patient.”
Although the exact cause of sarcoidosis is unknown, researchers suspect it is an immune disorder triggered by a group of specific antigens, which are generally foreign substances that incite an immune response in the body. In the United States, an estimated eight to 11 people per 100,000 are affected by sarcoidosis each year, according to previous research.
In the NIH project, scientists collected lung fluid samples and blood cells from patients with pulmonary sarcoidosis, then extracted the genetic material to identify antigens and determine which might be linked to sarcoidosis. Using a combination of molecular techniques, the researchers homed in on two newly described disease-specific antigen biomarkers that only bind to the antibodies of sarcoidosis positive patients.
The data allowed the team to design a highly specific blood test that only requires a small amount of blood to detect sarcoidosis. To validate the test, researchers compared blood samples from 386 people, which included patients with sarcoidosis, patients with tuberculosis, patients with lung cancer and healthy individuals. The researchers confirmed that their test was able to differentiate patients who had sarcoidosis from those with other respiratory diseases.
“More testing needs to be completed before this screening method is ready for clinical use, but it’s possible that could be a reality within a few years,” said Lobelia Samavati, MD, of Wayne State University and senior author on the study.