Enhanced Neointima Formation Following Arterial Injury in Immune Deficient Rag-1−/− Mice Is Attenuated by Adoptive Transfer of CD8+ T cells

T cells modulate neointima formation after arterial injury but the specific T cell population that is activated in response to arterial injury remains unknown. The objective of the study was to identify the T cell populations that are activated and modulate neointimal thickening after arterial injury in mice. Arterial injury in wild type C57Bl6 mice resulted in T cell activation characterized by increased CD4 + CD44 hi and CD8 + CD44 hi T cells in the lymph nodes and spleens. Splenic CD8 + CD25 + T cells and CD8 + CD28 + T cells, but not CD4 + CD25 + and CD4 + CD28 + T cells, were also significantly increased. Adoptive cell transfer of CD4 + or CD8 + T cells from donor CD8−/− or CD4−/− mice, respectively, to immune-deficient Rag-1−/− mice was performed to determine the T cell subtype that inhibits neointima formation after arterial injury. Rag-1−/− mice that received CD8 + T cells had significantly reduced neointima formation compared with Rag-1−/− mice without cell transfer. CD4 + T cell transfer did not reduce neointima formation. CD8 + T cells from CD4−/− mice had cytotoxic activity against syngeneic smooth muscle cells in vitro. The study shows that although both CD8 + T cells and CD4 + T cells are activated in response to arterial injury, adoptive cell transfer identifies CD8 + T cells as the specific and selective cell type involved in inhibiting neointima formation.