Undergraduate Research Symposium

CD8+ T cells are capable of killing tumor cells, but tumor cells have many ways to evade CD8+ T cells. One mechanism is the expression of B7-H1 (PD-L1) on the surface of tumor cells. Signaling events downstream of B7-H1 interacting with PD-1 on CD8+ T cells result in inhibition of cell proliferation and induction of apoptosis. B7-H1 also interacts with CD80, which is expressed on the surface of CD8+ T cells. The impact of B7-H1 interacting with CD80 is the focus of our studies. In order to study this we use two mouse lines, one wild type line that expressed CD80 and one knockout line that does not express CD80. Utilizing CD8+ T cells harvested from these mice, we have found that activated CD80 knock-out CD8+ T cells survive better than activated wild-type CD8+ T cells when cultured with plate-bound B7-H1 protein and anti-CD3. We are currently investigating the signaling events that occur downstream of B7-H1 interacting with CD80 on effector CD8+ T cells that could contribute to the induction of apoptosis of CD8+ T cells.