Early infiltration of arterial intima by activated dendritic γ/δ T-cells in ligated human arteries: An ultrastructural and immunocytochemical study

Abstract

To clarify the role of immune mechanisms in the vascular response to injury in humans, the sequence, subset and activation status of lymphocytes infiltrating acutely ischemic arteries were studied. Thirty-five branches of mesenteric arteries removed from 8 men during surgery—22 of which were ligated for 0.5–4 hours—were examined ultrastructurally and immunocytochemically. The ligated arteries showed early intimal infiltration by activated T-cells, the predominant subset of which was dendritic, γ/δ T-cell receptor (TCR)-bearing and phenotyped CD3+, CD4-, and CD8-. Their activated status is shown by strong HLA-DR positivity, expression of interleukin-2 receptors, increased expression of lymphocyte function antigen-1, and frequent lymphocyte-macrophage interactions. Intimal macrophage infiltration consisted of single cells in the earlier biopsy specimens and clusters of cells in the later ones. These findings suggest that an early immune mechanism initiated by activated γ/δ dendritic T-cells, and amplified later by macrophages, may play a pivotal role in the inflammatory response after acute arterial injury.