PTX3 immunohistochemistry staining in paired human arteries and veins. Immunohistochemistry with PTX3 staining in representative paired human arteries and veins from the same patient. The irradiated neck artery (A) shows positive staining, mainly confined to the endothelium compared to the non-irradiated radial artery (B). A difference in PTX3 staining was less evident when an irradiated neck vein (C) was compared to the non-irradiated forearm vein from the same patient (D). XRT = Irradiated vessel.