• To investigate the effect of Rituximab on subjective disease symptoms including oral dryness, ocular dryness, myoartralgia and fatigue. [ Time Frame: Baseline, Day 22 after second treatment, 1 month, 3 months and 6 months after treatment. ] [ Designated as safety issue: No ]
  

• To study the effect of Rituximab: on the structural changes (focal lymphocytic infiltrates) in the labial salivary gland tissue, including changes in the T- and B-cell ratio in the infiltrates as well as in the expression of M3-receptors [ Time Frame: Baseline and 6 months after treatment ] [ Designated as safety issue: No ]
  
• On the salivary gland function, incl. the production and composition of whole saliva and parotid saliva, the cellular signalling mechanisms and also the distribution of M3-receptors (M3R), the expression of aquaporins, [ Time Frame: Baseline, 1 month, 3 months and 6 months after treatment ] [ Designated as safety issue: No ]
  
• On the circulating serum autoantibodies (anti-SSA/-SSB, rheumatoid factors) and on antibodies against the M3R and α-fodrin and on the IgG level. [ Time Frame: Baseline, 1 month, 3 months and 6 months after treatment ] [ Designated as safety issue: No ]
  
• On the phenotype of circulating T- and B-cells as well as cytokines and immunoregulators, especially BLyS/BAFF. [ Time Frame: Baseline, 1 month, 3 months and 6 months after treatment ] [ Designated as safety issue: No ]
  
• On the function of the tear glandula, including the quantity and quality of tear as well as the extent of corneal changes. [ Time Frame: Baseline, 1 month, 3 months and 6 months after treatment ] [ Designated as safety issue: No ]
  
• To evaluate the side-effects in relation to the use of Rituximab-/placebo treatment. [ Time Frame: After first and second treatment and after 1 month ] [ Designated as safety issue: Yes ]
  

Drug: MabThera (rituximab)
1000 mg infusion twice with 14 days interval
Drug: Rituximab, Mabthera
1000 mg Rituximab infusion in 500 ml isotonic sodiumchloride twice with 14 days interval

The trial is designed as a double-blind parallel comparison between 2 infusions of 1 g Rituximab and solvent (saline) given two weeks apart, in 22 patients with the diagnosis of primary Sjögren's syndrome as based on the current American-European consensus classification criteria. The patients will be followed at the Department of Oral Medicine, Clinical Oral Physiology, Oral Pathology & Anatomy, University of Copenhagen, the Department of Rheumatology, Rigshospitalet and at the Department of Ophthalmology, Rigshospitalet.

The primary endpoints are clinical and a response has been delineated as at least 50% improvement in score. With the provision that this occurs for any item in at least 60% of the treated patients as compared to 1% in the control patients, a power of over 80% at doubled sided significance level of 5% is found with 20 patients.The patients will be followed within this study for 6 months after Rituximab.

The study will allow the first real dynamic appraisal of the immunologic pathophysiology in Sjögren's syndrome. Hence attempts will be made to determine at the best possible level if and how Rituximab influences and possibly resets the autoimmunity both at the whole body and particularly at the local level in the salivary glands. Also the basal transport mechanism in salivary secretion which must necessarily be perturbed in Sjögren's syndrome will be scrutinized employing the best available of techniques. Every possible effort to envisage a priory, and then monitor, the decisive mechanisms has been made.

In particular this includes repetitive biopsies from the parotid glands, which will allow combining functional and structural data to reduce as much as possible random variability of crucial quantities. Also this will allow for the first time to assess the relative and combined utility of obtaining biopsies from both the parotid and labial salivary glands.

Roche A/S provide investigational medicine, but the study was initiated and is entirely controlled by the investigators.