Ultrastructural observations of skin lesions in MRL mice--dermoepidermal junction.

The MRL-lpr/lpr (MRL/l) mouse, a new animal model for the study of human systemic lupus erythematosus (SLE), shows characteristic skin manifestations in addition to several systemic autoimmune phenomena. The ultrastructural changes observed in the dermoepidermal junction (DEJ) and in the uppermost dermis were: infolding of the DEJ; deformities of the basal lamina--partial disappearance, thickening, hanging down, duplication, and separation from the basal cell membrane; basal laminalike dense material in the uppermost dermis and increased anchoring fibrils; particles composed of circulated half-desmosomes between the basal cells and the basal lamina, and in the uppermost dermis with or without an enclosing basal lamina; cell processes of the basal cells; and invagination of the basal lamina in the basal cells. Most of these findings were similar to the ultrastructural changes observed in the skin lesions of human SLE. The skin eruptions of MRL/l mice might be a new aid in the investigation of the pathogenesis of the skin lesions of human SLE.