Inflammatory arthropathy in MRL hematopoietic chimeras undergoing Fas mediated graft-versus-host syndrome.

OBJECTIVE: To determine whether overexpression of the Fas ligand (FasL) on activated lpr T lymphocytes could induce arthritic lesions when grafted into syngeneic wild-type MRL mice expressing normal Fas receptor levels.
METHODS: Lethally irradiated MRL+/+ mice were reconstituted with congenic MRL/lpr bone marrow cells and splenocytes overexpressing FasL. Fas-mediated cytotoxic properties of repopulating lpr splenic lymphocytes were evaluated in vitro. Simultaneously, the hind paw ankles of the hematopoietic chimeras were histologically examined.
RESULTS: The lpr lymphocytes repopulating the spleen overexpressed FasL and had in vitro Fas-mediated cytotoxic activity. Simultaneously, in vivo, articular (synovitis, pannus) and periarticular (periostitis) inflammation with bone resorption were observed.
CONCLUSION: Arthritic lesions may be induced in Fas-expressing recipients by persistent engrafted syngeneic lymphocytes overexpressing FasL.