- Increased salivary gland tissue expression of Fas, Fas ligand, cytotoxic T lymphocyte-associated antigen 4, and programmed cell death 1 in primary Sjögren's syndrome. Bolstad, A.I., Eiken, H.G., Rosenlund, B., Alarcón-Riquelme, M.E., Jonsson, R. Arthritis Rheum. (2003)