This study consists of three consecutive parts. Part 1 in primary Sjögren's syndrome (pSS) patients (n=2-6) and Part 2 in healthy voluteers (n=3) are feasibility studies to assess if the selected [Zr-89]-rituximab PET/CT method is a valid method to assess B cells in salivary glands of pSS patients. In Part 1 and Part 2 no IMP will be applied to the subjects. In Part 3, pSS patients (n=12) will receive the IMP, VAY736. Posted information will be focused on Part 3.

The overarching purpose of this study is to test a new drug (VAY736) for the treatment of pSS. In pSS, the salivary glands (the glands that produce saliva) and other organs are affected by inflammation. A certain type of white blood cells called B cells prominently infiltrate the salivary glands in pSS, whereas they are not present in healthy salivary glands. Scientific evidence suggests that B cells may be involved in the disease process in pSS and that eliminating B cells may benefit patients with pSS. This study will test a new imaging method and a new treatment for pSS. Both the imaging method and the treatment are specific for B cells.

Part 1 and 3:

Inclusion Criteria:

• Fullfilled consensus criteria for primary Sjögren's syndrome
• Patients must have elevated serum levels for some Sögren Syndorme specific parameters such as antinuclear antibodies (ANA), rheumatoid factor (RF) etc.

Exclusion Criteria:

• Patients that are suffering from Secondary Sjögren's syndrome.
• Patients previously treated with monoclonal antibody treatments such as rituximab, infliximab, adalimumab, etc.

Part 2

Inclusion criteria:

- healthy male and female people 18-75 years of age

Exclusion criteria:

• Use of other investigational drugs at the time of enrollment
• Exposure to a sizeable degree of radiation (≥ 5 mSv) in an investigational research study in the past year prior to this study