Methodology
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Enzyme Linked Immunosorbent Assay (ELISA)
This test has been developed and performance parameters have been validated by IMMCO Diagnostics, Inc. This test has not been approved by the U.S. Food and Drug Administration (FDA); however, US FDA approval is not required for clinical use. It is not intended that clinical diagnosis and patient management decisions be made using these results alone. This test has been validated using serum samples. The manufacturer has not determined the efficacy of this test when performed on CSF, plasma, joint, or pleural fluid specimens. The performance characteristics of this test were determined by IMMCO Diagnostics, Inc.
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Days Performed
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Set up: Mon a.m. (once every 2 weeks); Report available: 15 days from time of receipt.
Sjogren's syndrome (SS) is a systemic autoimmune disease in
which loss of salivary gland and lachrymal gland function is
associated with hypergammaglobulinemia, autoantibody production,
mild kidney and lung disease and eventually lymphoma. SS involves
dry eyes and dry mouth without systemic features that may be either
primary or secondary to another autoimmune disease, such as SLE.
Patients with SS and picked up at a late stage in their disease,
after the salivary glands and lachrymal glands are already
destroyed, because they are asymptomatic until that time. At this
point, only symptomatic treatment can be offered for abnormal
lachrymal and salivary gland function. The diagnosis for SS is
currently at a crossroad with the American College of Rheumatology
providing which requires characteristic autoantibodies (SS-A/SS-B)
or minor salivary gland biopsy. Since lip biopsies are not
frequently performed in clinical practice, there is increased
emphasis placed on autoantibodies in diagnosis. The current Ro and
La antibodies can delay the diagnosis by over 6 years.Recently
novel antibodies identified to salivary gland protein 1 (SP-1),
carbonic anhydrase 6 (CA6) and parotid secretory protein (PSP)
using western blot methodology. Further studies have shown that the
isotype differentiation of the markers adds to the sensitivity of
diagnosis of SS. These autoantibodies occurred earlier in the
course of the disease than antibodies to Ro or La. In addition
antibodies to SP-1, CA-6 and PSP were found in patients meeting the
criteria for SS who lacked antibodies to Ro or La. Furthermore, in
patients with idiopathic xerostomia and xerophthalmia for less than
2 years, 76% had antibodies to SP-1 and/or CA6 while only 31% had
antibodies to Ro or La.
Antibodies to different isotypes (IgG, IgM & IgA of SP-1, CA6
and PSP are useful markers for identifying patients with SS at
early stages of the disease or those that lack antibodies to either
Ro or La.
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