SKIN ALLOGRAFT-REJECTION IN CD28-DEFICIENT MICE

Costimulatory interactions between CD28 and the B7 family have been sh own to augment T cell responses in general, To further assess the impo rtance of the costimulatory signals generated through CD28, the alloge neic response was examined in CD28-deficient mice. T cells hom CD28-de ficient mice showed reduced proliferation and cytokine production in r esponse to allogeneic stimulator cells in vitro. However, CD28-deficie nt T cells developed cytotoxic activity against allogeneic target cell s in vitro and efficiently rejected skin allografts in vivo. These res ults suggest that the costimulatory signals through CD28 are not essen tial for the induction of alloreactive effector functions in vitro or in vivo.