Assessment of T cell function with a skin allograft assay

The adoptive transfer of cytotoxic effector cells to induce accelerated skin allograft rejection in the normal murine host was used as an assay of lymphocyte function in vivo. Splenocytes sensitized in vivo caused specific accelerated skin allograft rejection when administered i.v. at a dose of 5 X 10(7) cells 1 day after grafting. Graft rejection was specific for the immunizing alloantigen and could not be transferred with freeze-thawed or irradiated cytotoxic cells. In this assay the i.v. and local routes of administering cytotoxic cells were effective whereas the i.p. and s.c. routes were not. T cells were necessary in that pretreatment of the cells with anti-Thy-1.2 plus rabbit complement abrogated this phenomenon. Immune cells from spleens of mice sensitized but no longer actively cytotoxic did not demonstrate in vivo activity. If hyperimmunized mice were challenged by i/p. allogeneic tumor, their spleen cells were highly cytotoxic by in vitro assay but acted as suppressor cells in vivo by prolonging skin graft survival. Adoptively transferred in vivo sensitized cells subsequently expanded in number by T cell growth factor did not demonstrate in vivo activity. This skin allograft assay may be used to demonstrate T cell activity in vivo by inducing accelerated allograft rejection, and immune suppression by prolonging graft survival. Also a comparison of in vivo and in vitro effects was possible.