Hutch News

Bridging the diagnostic gap for deadly form of lupus

Sept. 5, 2002

The U.S. Food and Drug Administration has cleared for market a new screening test for lupus developed by a researcher in the Basic Sciences Division.

The test is considered the first significant diagnostic breakthrough for systemic lupus erythematosus, or SLE, in more than four decades.

The test is expected to pick up the 20 percent of SLE cases that previously fell through the cracks because they could not be detected by the most widely used, standard screening test.

Lupus is a chronic disorder in which a person's immune system attacks the body. SLE is the most severe and potentially fatal form of the disease, which causes inflammation of connective tissue throughout the body, from the joints to the kidneys. Because symptoms range from skin rash and mild fatigue to organ failure, diagnosis can be difficult.

One-fifth undiagnosed

While the majority of lupus patients produce antibodies to their own tissue that can be detected with a blood test that's been available since the early 1960s, about one-fifth of patients - those who do not make such antibodies - often go undiagnosed.

The new test, developed by Dr. Mark Roth, promises to bridge that diagnostic gap.

"This test will improve the ability for doctors to make correct decisions when diagnosing SLE, and we also have evidence that this test is of value in determining where in the body the disease will present itself," said Roth, also an affiliate associate professor of biochemistry at the University of Washington School of Medicine.

Two years ago, in the August 2000 issue of Arthritis and Rheumatism, Roth and colleagues at Fred Hutchinson and the University of Washington, in collaboration with New York Medical College rheumatologist Dr. Robert G. Lahita, first reported the discovery that molecules called SR proteins are particularly useful biomarkers for lupus because the majority of patients produce antibodies to them.

This discovery spawned the development of a color-coded test to detect the presence of telltale SR proteins in the serum, the clear-fluid portion of the blood. The test, called the "Anti-SR protein antibody assay," involves adding sera to tiny wells in a plastic plate that has been coated with human SR proteins. A colored molecular tag detects antibodies in the sera that stick to the SR proteins. Sera from people with lupus turns purple, while sera from non-affected individuals remains clear. This test can identify 50 percent to 70 percent of lupus patients who react positively to SR proteins.

"It is often difficult to predict who will flare from lupus or when. This test makes it easier to make such predictions," said Lahita, professor of medicine at NYMC and chief of rheumatology at St. Vincent's Hospital and Medical Center, who has authored several textbooks and publications about immune diseases and lupus and is the editor of Systemic Lupus Erythematosus.

Initial idea a decade ago

The initial idea behind the test arose from a scientific experiment more than a decade ago, when Roth and colleagues injected mice with extracts of frog nuclei. Antibodies produced by these mice led to the discovery of the SR proteins used in this new screening test.

Fred Hutchinson has filed for patent protection on this assay system and is actively seeking a commercial partner that can make the test available to the public in the near future.

"FDA clearance should facilitate the transfer of this technology to companies that can make the test widely available to the public," said Linda Clarke, director of the center's Technology Transfer Office.

Funding for this research came from the National Institutes of Health and Fred Hutchinson's New Technology Development Fund.

The fund helps translate basic research to public benefit by providing funding to demonstrate proof-of-principle.

 

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