To distinguish potential autoimmune and nonautoimmune mechanisms underlying the salivary gland inflammation seen in Sjögren's syndrome and normal aging.
Immunohistochemical studies were conducted on the lacrimal and salivary glands of 2- and 5-month-old C3H.MRL-Faslpr autoimmune strain mice and age-matched C3H/HeJ nonautoimmune controls.
Glandular inflammatory foci, interstitial areas, and vasculature were stained for immunoglobulin G (IgG), immunoglobulin A (IgA), and complement to determine differences in their local immune parameter. Differences between the two strains were compared for immune changes attributable to autoimmune disease and between the two normal groups for normal aging changes.
Greater staining of IgG, IgA, and complement occurred in the inflammatory foci and interstitial areas of 5-month-old C3H.MRL-Faslpr lacrimal and submandibular glands compared with 5-month-old controls. Normal mice showed some increased immunoglobulin staining with aging, but little or no complement in any glands.
These differential findings suggest that the systemic autoimmune disease plays a more direct role in focal glandular inflammation in Sjögren's syndrome, whereas less severe immune mechanisms are involved in the inflammation of normal glands.