CD40 co-stimulatory molecule expression by dendritic cells in primary atherosclerotic lesions in carotid arteries and in stenotic saphenous vein coronary artery grafts

We have previously identified dendritic cells in the intima of human large arteries and stenotic vein coronary bypass grafts. The mechanisms by which these dendritic cells might regulate immune responses in atherosclerotic lesions and stenotic vein grafts are unknown. The aim of the present study was to investigate whether dendritic cells in carotid plaques and in stenotic aortocoronary vein grafts express an immunoregulatory molecule CD40. Segments of wall from eight carotid arteries and three stenotic aortocoronary saphenous vein grafts were obtained at operation. CD40 + cells were detected in all specimens of both occluded and stenotic grafts and carotid plaques. Although CD40 + cells of various cell types were intermingled in most areas within the plaques and stenotic grafts, there were sites where CD40 + cells were located in small groups. Consecutive sections demonstrated that a small population of CD40 + cells stained positively for S100. These CD40 +/S100 + cells were clustered within the intima but were also found in the media and adventitia. This suggests that dendritic cells, which accumulate within vessels affected by atherosclerosis and graft disease, express CD40 co-stimulatory molecule. The expression of CD40 molecule on the dendritic cells may be important in regulating T cell responses within atherosclerotic plaques and stenotic vein grafts.