T h 1 cells are cytotoxic effector cells that utilize Fas ligand (FasL) and tumor necrosis factor. The physiological roles of cytotoxic T h 1 cells are considered to be immunoregulation by eliminating autoreactive lymphocytes or hyper-activated foreign antigen-specific lymphocytes. Their pathological roles, however, remain to be clarified. To investigate whether T h 1 cells can destroy organs, we generated a Propionibacterium acnes-specific T h 1 clone from C57BL/6 mice and tested whether the

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... one could serve as an effector in a P. acnes-primed lipopolysaccharide (LPS)induced hepatic injury system, one of the septic shock models. B6Smn.C3H-FasL gld (B6-gld) mice, which were deficient in functional FasL, were resistant to P. acnes/LPS-induced hepatic shock. The T h 1 clone rendered B6-gld mice sensitive to the hepatic shock after the i.v. transfer. The hepatic injury in the clone-transferred B6-gld mice, which was evaluated by both biochemical and histological examination, was inhibited by an anti-FasL mAb that we developed. These results suggested that bacterial antigen-specific T h 1 cells like this clone can participate in organ destruction in vivo as one of the cytotoxic effectors and play a critical role in endotoxin-induced hepatic injury.