To determine whether the destruction of salivary gland epithelial cells in Sjögren's syndrome (SS) could be mediated by granzyme A, a serine protease that is contained in the granules of activated lymphocytes.
We used in situ hybridization and polymerase chain reaction amplification to determine the expression of granzyme A messenger RNA (mRNA) in salivary gland biopsy samples.
Granzyme A mRNA expression was detected in salivary glands from SS patients, but not in those from normal controls. Granzyme A mRNA content was significantly correlated (P < 0.001) with the size of lymphocytic infiltrates in the salivary glands and with the clinical activity of the disease.
Cells that express granzyme A mRNA may play a role in the destruction of the target organ (i.e., the salivary gland) in patients with SS. The strong association of granzyme A mRNA expression and larger lymphoid infiltrates in the patients' salivary glands suggests that granzyme A mRNA is expressed at a relatively late stage of the local inflammatory process. Therapies designed to modulate or block granzyme A induction and action should be investigated in SS patients.