New research finds a model for the detection of ANA results 'false positives'
The presence of antinuclear antibodies (ANA) indicates the possibility of autoimmunity and indirect immunofluorescence (IIF) assay on HEp-2 is the standard blood tests (ANA HEp-2) used to detect ANA. However, some studies have shown that a "false positive" ANA testing occurs in up to 13% of healthy individuals. In these cases, the test detects the presence of autoantibodies that are apparently not associated with autoimmune diseases. Researchers in Brazil have discovered the distinctive features of ANA testing in healthy individuals and patients with autoimmune diseases, reducing the likelihood of misdiagnosis autoimmune disease. Their findings are published in the January issue of Arthritis & Rheumatism 2011, a journal of the American College of Rheumatology (ACR).
The immune system is responsible for protecting the body against foreign invaders and infection, but in some people the immune system attacks healthy cells of the body repeatedly, causing an autoimmune disease. According to the Centers for Disease Control and Prevention (CDC), autoimmune diseases, including rheumatoid arthritis, Sjögren syndrome, systemic lupus erythematosus, and affect up to 8% (22 million individuals) of the U.S. population.
The Brazilian research team led by Luis Andrade, MD, PhD, at the Federal University of São Paulo, enrolled 918 healthy subjects (634 females and 284 males) aged between 18 and 66 for this study. In the control group were 153 patients with autoimmune rheumatic diseases that included lupus (87), systemic sclerosis (45), Sjögren's syndrome (11) and idiopathic inflammatory myopathy (10). To determine the blood concentration of ANA, ANA HEp-2-tests were performed on all participants and considered positive if a well-defined pattern of IIF was identified.
"The HEp-2 ANA test is positive for a considerable part of the general population and our findings distinguishing characteristics between healthy individuals and patients with autoimmune disease that is essential to correctly interpret the test results," said Dr. Andrade . The researchers determined that HEp-2-positive ANA tests in healthy subjects occurs predominantly as a nuclear fine speckled (NFS) model (a low level of moderate) or as a dense fine speckled nuclear (NDF) model (often as high) in 46% and 33% of ANA-positive healthy subjects , respectively. healthy participants did not present a coarse nuclear speckles (NCS) or a homogeneous nuclear (I) model.
In those with autoimmune disease, the ANA HEp-2 showed positive results in a predominantly moderate to high titre. A distinct ANA HEp-2-profile model was observed, characterized by the presence of NDF and exclusive model of NCS (26%), centromeric (8%), homogeneous nuclear (7%), and cytoplasmic dense fine speckled (3%) models. ANA-positive patients with confirmed autoimmune disease also showed the presence of NFS (42%), but with a title higher than in healthy individuals.
At the end of a 4-year follow-up 73% of ANA-positive healthy individuals maintained a positive result, but do not develop any symptoms of autoimmune rheumatic disease. "Our study confirms that the HEp-2 ANA model is essential in properly diagnosing autoimmune disorders and future research should try to reproduce the interpretation of test results between different experts and ANA-HEp-2 ANA slides brands, "Dr. Andrade said. Arthritis & Rheumatism
SOURCE
The immune system is responsible for protecting the body against foreign invaders and infection, but in some people the immune system attacks healthy cells of the body repeatedly, causing an autoimmune disease. According to the Centers for Disease Control and Prevention (CDC), autoimmune diseases, including rheumatoid arthritis, Sjögren syndrome, systemic lupus erythematosus, and affect up to 8% (22 million individuals) of the U.S. population.
The Brazilian research team led by Luis Andrade, MD, PhD, at the Federal University of São Paulo, enrolled 918 healthy subjects (634 females and 284 males) aged between 18 and 66 for this study. In the control group were 153 patients with autoimmune rheumatic diseases that included lupus (87), systemic sclerosis (45), Sjögren's syndrome (11) and idiopathic inflammatory myopathy (10). To determine the blood concentration of ANA, ANA HEp-2-tests were performed on all participants and considered positive if a well-defined pattern of IIF was identified.
"The HEp-2 ANA test is positive for a considerable part of the general population and our findings distinguishing characteristics between healthy individuals and patients with autoimmune disease that is essential to correctly interpret the test results," said Dr. Andrade . The researchers determined that HEp-2-positive ANA tests in healthy subjects occurs predominantly as a nuclear fine speckled (NFS) model (a low level of moderate) or as a dense fine speckled nuclear (NDF) model (often as high) in 46% and 33% of ANA-positive healthy subjects , respectively. healthy participants did not present a coarse nuclear speckles (NCS) or a homogeneous nuclear (I) model.
In those with autoimmune disease, the ANA HEp-2 showed positive results in a predominantly moderate to high titre. A distinct ANA HEp-2-profile model was observed, characterized by the presence of NDF and exclusive model of NCS (26%), centromeric (8%), homogeneous nuclear (7%), and cytoplasmic dense fine speckled (3%) models. ANA-positive patients with confirmed autoimmune disease also showed the presence of NFS (42%), but with a title higher than in healthy individuals.
At the end of a 4-year follow-up 73% of ANA-positive healthy individuals maintained a positive result, but do not develop any symptoms of autoimmune rheumatic disease. "Our study confirms that the HEp-2 ANA model is essential in properly diagnosing autoimmune disorders and future research should try to reproduce the interpretation of test results between different experts and ANA-HEp-2 ANA slides brands, "Dr. Andrade said. Arthritis & Rheumatism
SOURCE
0 comments:
Post a Comment