ORAL MUCOSAL LESIONS IN EXPERIMENTAL GRAFT-VERSUS-HOST DISEASE - MORPHOLOGICAL AND IMMUNOHISTOCHEMICAL CHARACTERIZATION OF INFILTRATING CELLS

To facilitate recognition of the oral mucosal lesion that develops in rats with graft-versus-host disease (GVHD) induced by injecting spleen cells of parental strain rats (Brown Norway) into non-irradiated (Bro wn NorwayXLewis) F1 hybrid rats, we followed the development of the to ngue lesion histologically and immunohistochemically. This assessment revealed an increase in the number of MHC class II+ cells with dendrit ic shape in the lamina propria to br the earliest stage of the tongue lesions in GVHD rats. The subsequent mononuclear cell infiltration wit h epithelial cell destruction, characteristic of GVHD, consisted of CD 8(+) cells and macrophages. Our findings seem to indicate that MHC cla ss II+ cells with dendritic shape may provide antigen presentation in the induction of local immunological responses, including tissue destr uction, by CD8(+) cells and macrophages in the tongue of GVHD rats.