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.
