CD8(-LYMPHOCYTES PRODUCE AN IN-VITRO SKIN GRAFT-VERSUS-HOST REACTION IN AN ORGANOTYPIC SKIN CULTURE MODEL() ACTIVATED T)

We adapted organotypic skin cultures to the dog as a model for skin gr aft-versus-host reaction (GVHR) to explore the relative roles of T cel ls and cytokines. To produce GVHR, activated lymphocytes from bulk mix ed leukocyte cultures (bMLC) from 2 dog leukocyte antigen-unrelated do gs were injected into organotypic skin cultures. Additionally, effects of separated CD4(+) and CD8(+) activated lymphocytes as well as cytok ine-containing (TNF alpha and IFN gamma) supernatants from bMLC were s tudied. Noninjected cultures as well as cultures injected with autolog ous (cultured and uncultured) lymphocytes and allogeneic uncultured ly mphocytes served as controls. The unseparated bMLC-activated cell popu lations induced histopathological changes similar to in vivo skin GVHR along with very prominent class II antigen expression on keratinocyte s. Separated CD8(+) cells were directly involved in tissue damage by p roducing necrosis of epidermis at the site of injection, with less cla ss II antigen expression on keratinocytes, and predominantly distribut ed intraepidermally. CD4(+) cells, located mostly in the dermal region s, induced prominent class II antigen expression on keratinocytes, but no histological changes of GVHR. High levels of TNF alpha and IFN gam ma were found in the supernatant of allogeneic bMLC cultures, although when the supernatant was injected into the organotypic skin cultures, keratinocytes failed to express surface class II antigen and histolog ically did not show changes of skin GVHR. This study demonstrated that organotypic skin cultures can serve as a model for studying the etiol ogy of GVHR, and indicated direct involvement of CD8(+) cells in tissu e damage.