Antibody Detection Helps Primary Sjögren's Syndrome Diagnosis

Called luciferase immunoprecipitation technology (LIPS), the test has the potential to detect most developing autoimmune disorders before they become symptomatic, more closely monitor the changes in a patient's antibody counts over time, and track the immunological outcome of an autoimmune treatment.

Scientists at the National Institute of Dental and Craniofacial Research (NIDCR; Bethesda, MD, USA), part of the National Institutes of Health (NIH) used LIPS to identify the two antibodies SSB and SSA associated with Sjögren's syndrome. Peter Burbelo Ph.D., a scientist at NIDCR, and colleagues also used LIPS to profile additional antibodies that might be related to other largely unrecognized manifestations of the syndrome. These first-pass antibody profiles have the potential to help scientists define a range of clinical subtypes of primary Sjögren's, which could greatly improve diagnoses and enable better target treatment.

"Traditionally, the SSA antigen consists of two proteins--Ro52 and Ro60--that are conjoined and anchored on the plastic diagnostic assays," said Mike Iadarola, Ph.D., an NIDCR scientist and senior author on the study. "We teased apart the two proteins to present their full three-dimensional shape and were able to measure the antibody response to each separately."

The group found that 42 of the study's 57 previously diagnosed Sjögren's patients had antibody reactions against a segment of the Ro52 antigen that does not elicit a response in the currently used enzyme-linked immunosorbant assay (ELISA). Overall, LIPS detected antibody responses against each protein in about 60 % of patients, roughly equal to an ELISA, but with a far greater dynamic range and perfect specificity.

The NIDCR team's initial study comprised 82 people, 57 of whom had well-characterized primary Sjögren's syndrome. Fourteen percent of the patients had antibodies against the thyroid antigen, 16 % had antibodies against an antigen associated with autoimmune gastritis, and 4% had antibodies linked to an autoimmune attack of the eye's peripheral nerve. The findings suggest that LIPS may be used as a substitute for more invasive and expensive procedures typically used to diagnose these peripheral conditions.

The study was published online the journal Autoimmunity August 3, 2009." Again, this study is just a start," said Dr. Burbelo. "All of these tests can be performed on the automated robotic machine in my laboratory, and we can do thousands a day. There's more data to come."

Primary Sjögren's syndrome is a chronic autoimmune disorder that affects about four million Americans, 90 % of whom are women. Scientists have long thought the syndrome is triggered when white blood cells mistakenly attack the body's moisture-producing glands, typically causing chronic dry mouth, dry eyes, and arthritis.

Sjögren's-related health problems continue to be reported in the medical literature, including lymphoma, thyroid dysfunction, painful peripheral neuropathy, and gastrointestinal problems. These seemingly phantom symptoms remain poorly defined, diagnostically controversial, and suggest a more systemic and yet-to-be-defined underlying pathology.

Related Links:
National Institute of Dental and Craniofacial Research
National Institutes of Health