Hypotheses: Dysfunction of the parasympathetic nervous system has a partial role in the pathogenesis of the symptoms of Sjögren’s syndrome (SS). This autonomic dysfunction is caused by autoantibodies reacting with the acetylcholine-receptor (AchR).

Examinations: With molecular genetic methods, we wish to prepare antigen-determinant epitopes of the m3 type AchR (m3AchR), which is the functionally dominant subtype of the receptor in the salivary and lachrymal glands. With immunological methods, we wish to determine the occurrence of antibodies reacting with the receptor in 80-90 SS patients. To assess the clinical significance of the putative anti-m3AchR autoantibodies, in a prospective clinical trial, we shall examine whether there is a correlation between the antibody titers and the severity of the impairment of the tear and saliva production.

To assess whether these antibodies affect the function of the parasympathetic innervation of certain other organs via binding to the AchR-s in these organs, we wish to perform cardiovascular reflex tests, and the clinical examinations of the heart-rate variability, the gastric emptying and the urinary bladder function. Similarly to the m3AchR, we plan to prepare the antigen-determinant epitopes of the m1 and m2 receptor subtype, which are the functionally dominant subtypes in the above-mentioned organs, and we should like to examine the reactions between these peptides and the serum samples of SS patients.

Benefits of the anticipated results: The results may contribute to an understanding of the pathogenesis of SS, increase our knowledge about the clinical spectrum of the disease, with special emphasis on the dysfunction of the autonomic nervous system, provide diagnostic aid, and may furnish general physiological information.