Immunoglobulin (Ig) G4-related dacryoadenitis and sialadenitis, the so-called Mikulicz's disease (MD), is a chronic inflammatory disease. However, little is known about its pathogenesis and pathological condition. In the present study, we used immunohistological techniques to compare the roles of cytotoxic T lymphocytes (CTLs) in MD and primary Sjogren's syndrome (SS). We examined the state of CTLs [cytotoxic granule-positive rate and programmed death-1 (PD-1) expression rate] in the salivary glands.
The study samples comprised 12 submaxillary glands from untreated MD patients and 12 labial glands from SS patients. We performed immunofluorescence and multicolor immunofluorescence to stain CD8, perforin (PRF), granzyme B (GZMB), and PD-1. We measured the total number of CTLs as well as the PRF(+)CTLs, GZMB(+)CTLs, and PD-1(+)CTLs.
We found that the degree of infiltration of CTLs was equal in MD and SS, but the rate of CTLs with cytotoxic granules, especially PRF, in MD was less than in SS. In addition, the frequency of PD-1(+)CTLs in MD was higher than that in SS.
Cytotoxic granule-positive CTLs were in the minority in D salivary glands, and this regulation might relate to PD-1 signals like the state of exhaustion and anergy.