Experimentally induced pemphigus vulgaris in neonatal BALB/c mice: a time-course study of clinical, immunologic, ultrastructural, and cytochemical changes.

Pemphigus vulgaris autoantibodies (PV IgG) promote cell detachment in epidermal cell cultures and acantholysis in the epidermis of neonatal BALB/c mice in vivo. We have studied the evolution of the immunologic and ultrastructural changes in the epidermis of BALB/c mice that receive parenteral injections of PV IgG. Neonatal BALB/c mice received a single i.p. injection of PV IgG (10 mg/g body weight) or control IgG from normal humans. The skin and serum of these animals was obtained at 0, 1, 3, 6, 12, 18, and 24 h post injection, and examined by immunofluorescence (IF), electron microscopy (EM), and immunoelectron microscopy (IEM). PV IgG was detected in the mouse serum and bound to the epidermal cells as soon as 1 h after injection by IF and IEM. The intensity of the binding in the skin (by IF) increased sharply between 3 and 6 h, and remained positive at 24 h. Early epidermal cell detachment was demonstrable by EM at 1 h as widening of the epidermal intercellular spaces (ICS), and by 6 h the ICS between desmosomes had detached completely. Desmosomal junctions are the last to separate, occurring at 12-18 h. At this point, complete cell detachment occurred in the suprabasilar layers of the epidermis. Basal cells remain attached to the underlying dermis (tombstone row). Coincident with cell detachment, intracellular tonofilaments retracted from the cell periphery and clustered in a perinuclear position. IEM confirmed the binding of PV antibodies to the surface of epidermal cells in early and established lesions. This study demonstrates that the early immunologic and ultrastructural changes that occur in human pemphigus vulgaris are reproduced in this mouse model of the disease.