Exocrine Gland Disorder
المؤلف:
Mary Louise Turgeon
المصدر:
Immunology & Serology in Laboratory Medicine
الجزء والصفحة:
5th E, P391-392
2025-09-22
134
Sjögren’s Syndrome
Etiology. Sjögren’s syndrome is a chronic inflammatory dis ease of unknown cause that affects lacrimal, salivary, and other excretory glands. It results in keratoconjunctivitis sicca and xerostomia.
As with RA and SLE, causative factors include infection, abnormalities of immune regulation, and genetic factors. Development of Sjögren’s syndrome is strongly associated with HLA-B8 and HLA-DR3. An infectious origin has been suggested. Clear evidence for excessive B cell activity has been demonstrated, but it is not known whether this is caused by B or T cell abnormalities.
Epidemiology. A primary form is not associated with other diseases; a secondary form is associated with RA and other connective tissue diseases. About 90% of patients are women. A 44-fold increased incidence of lymphoma has been noted in patients with Sjögren’s syndrome.
Signs and Symptoms. The main clinical manifestations of Sjögren’s syndrome are dry eyes, dry mouth, and recurrent salivary gland pain and swelling (Table 28-5). Hoarseness, chronic cough, and increased incidence of infection have been observed. Dryness of the vagina leads to dyspareunia and itching. Dysphagia and atrophic gastritis can also be present. Extraglandular involvement results in interstitial pneumonitis and fibrosis. Renal tubular acidosis and vasculitis involving the peripheral nerves and central nervous system (CNS) can also result from Sjögren’s syndrome.
Immunologic Manifestations. The immunologic characteristics of Sjögren’s syndrome include hypergammaglobulinemia, ANAs, rheumatoid factor, autoantibodies to salivary duct and other antigens, and lymphocyte and plasma cell infiltration of involved tissue. Antibodies are usually polyclonal and may result in the hyperviscosity syndrome and hypergammaglobulinemic purpura. Speckled or homogeneous ANA patterns are present in 65% of patients and occur more frequently in primary Sjögren’s syndrome. Antibodies to Sjögren’s syndrome A antigen have been associated with vasculitis in primary Sjögren’s syndrome. Antibodies to Sjögren’s syndrome B antigen are almost always found in association with Sjögren’s syndrome A antigen and only occur in SLE and Sjögren’s syndrome. Rheumatoid factor is found in 90% of cases. A rather new autoantibody, anti–α-fodrin, has been found in the sera of most patients with primary Sjögren’s syndrome. This antibody may be pathophysiologically associated with some extraglandular manifestations characteristically seen in patients with Sjögren’s syndrome.
Autoantibodies to salivary duct antigens are frequently detected in patients with secondary Sjögren’s syndrome. They are also common in 25% of patients with RA without Sjögren’s syndrome. Mitochondrial antibodies are detected in 10% of patients with primary Sjögren’s syndrome and rarely in patients with secondary Sjögren’s syndrome and RA. Patients with primary Sjögren’s syndrome also have higher levels of antibodies to the thyroid gland, gastric parietal cells, pancreatic epithelial cells, and smooth muscle. Lymphocytic infiltration of the exocrine glands of the eyes, mouth, nose, lower respiratory tract, gastrointestinal (GI) tract, and vagina occurs. The infiltrate is composed of B and T cells. In tissue culture, these cells produce large amounts of IgM and IgG. T cells are predominantly helper cells.
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