New test for lupus

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Sep 10, 2002

New test for lupus

Seattle, WA A new screening test for systemic lupus erythematosus (SLE),

which could identify patients who are currently missed, has taken a step

closer to becoming available. The new test detects autoantibodies to SR

proteins, described for the first time 2 years ago.

Developed by researchers at the Fred Hutchinson Cancer Research Center in

Seattle, the test was recently cleared for marketing by the FDA, and the

institution is looking for a commercial partner to make the test widely

available to the public.

Dr Mark Roth (Fred Hutchinson Basic Science Division and University of

Washington School of Medicine) and colleagues described the importance of SR

proteins as autoantigens in patients with SLE 2 years ago in Arthritis and

Rheumatism [1]. In that paper, the team described how the test for SR

protein autoantibodies was positive in 52% of one group of SLE patients

(n=137) and in 50% in another group (n=102). In contrast, blood samples

taken from patients with other disorders, such as rheumatoid arthritis and

primary antiphospholipid syndrome, " reacted infrequently, " they commented.

The team also noted that the novel autoantibodies to SR proteins that they

describe are distinct from the autoantibodies to double-stranded DNA that

are usually tested for in diagnosing SLE.

Roth tells rheumawire that the test for double-stranded DNA is one of the

most widely used serologic tests for lupus and is able to detect about 80%

of diagnosed patients. The new test for SR proteins is positive in about 50%

to 70% of lupus patients and can pick up patients the other test has missed.

Some patients show positive on one test and not on the other, but there are

some patients who show positive in both tests, he says.

Roth sees the new test as complementing the current tests, rather than

replacing them. " It is critical to patients that they not be misdiagnosed.

False negatives and false positives cause patients either to be needlessly

given steroids (with their known side effects) or not to be given such

treatment and suffer the life-threatening symptoms associated with untreated

lupus, " he says. " This test, in combination with other ACR-approved tests,

improves the ability of physicians to make accurate predictions about who

does or does not have the disease. "

Diagnostic test may also have prognostic value

The test may also have prognostic value. Roth tells rheumawire that in

further studies that have not yet been published, his team screened blood

samples taken from SLE patients over a period of many years (10 or more) and

found that the SR autoantibodies correlate with a particular outcome. " We

have evidence that this test is of value in determining where in the body

the disease will present itself, " he says.

Roth's team collaborated on this research with rheumatologist Dr

Lahita (New York Medical School and St 's Hospital). Lahita comments:

" It's often difficult to predict who will flare from lupus or when. This

test makes it easier to make such predictions. "

Zosia Chustecka

Cited source

1. Neugebauer KM, Merrill JT, Wener MH, Lahita RG, Roth MB. SR proteins are

autoantigens in patients with systemic lupus erythematosus. Importance of

phosphoepitopes. Arthritis Rheum 2000 Aug; 43(8):1768-78.