DERMAL DENDROCYTES PARTICIPATE IN THE CELLULAR PATHOLOGY OF EXPERIMENTAL ACUTE GRAFT-VERSUS-HOST DISEASE

In a well established murine model relevant to human disease, graft-ve rsus-host disease results from recognition of recipient minor histocom patibility antigens by donor bone marrow-derived T lymphocytes. Previo us studies suggest that factor XIIIa-positive dermal dendrocytes may b e involved in the pathogenesis of disorders involving antigen presenta tion to T cells and dermal fibrosis. This study was undertaken to dete rmine (i) whether normal murine skin contains factor XIIIa-positive de rmal dendrocytes, and (ii) whether such cells participate in the patho physiology of acute graft-versus-host disease. Graft-versus-host disea se was produced using B10.BR CD8+ donor T cells administered to CBA re cipients. Skin samples were collected weekly for a 5-week period and e valuated by immunohistochemistry and electron microscopy Our data indi cate that normal murine dermis contains factor XIIIa-positive cells lo calized primarily around deep dermal microvessels. Ultrastructural ana lyses reveal these cells to have long precesses, pinocytotic vesicles, fibronexuses, and intimate associations with mast cells. During graft -versus-host disease, factor XIIIa-positive dendrocytes appeared withi n the superficial dermis. By ultrastructure, the dendrocytes were hype rtrophic and highly branched, and demonstrated an intimate relationshi p with neighboring cells. III conclusion, factor XIIIa-positive dendro cytes comprise a normal component of the murine dermis and undergo alt erations in experimental acute graft-versus-host disease consistent wi th participation in disease pathophysiology.