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⁺CD44hi 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. [ABSTRACT FROM AUTHOR]