Ultrastructural study of Sjögren's syndrome-like disease in MRL/l mice.

Salivary glands of autoimmune MRL/l mice were examined ultrastructurally and by immunoelectron microscopy to further characterize the Sjögren's syndrome-like disease in these animals. Major salivary glands from 12 female and 7 male MRL/l, two female MRL/n, and one female BALB/c mice were examined by electron microscopy and the glands from 4 female MRL/l mice were subjected to immunoelectron microscopy in order to detect Lyt-1 and Lyt-2 positive lymphoid cells. Mononuclear cell infiltrates were not seen in the salivary gland from the BALB mouse and occurred rarely in glands of MRL/n mice. However, in MRL/l mice, numerous lymphoid cells were present and acinar cells displayed low cytoplasmic density, cytoplasmic vacuolization and cellular lysis. Lymphoid cells were predominantly Lyt-1 positive although some Lyt-2 positive cells were observed. These results suggest that the MRL/l mouse represents a useful model for the study of the pathogenesis of Sjögren's syndrome in man.