Distribution of type VIII collagen in tissues: an immunohistochemical study.

Type VIII collagen was first detected as a secretion product of diverse endothelial cell cultures, including those derived from aorta, arteries and veins. Initial studies of its tissue distribution (using a monoclonal antibody) showed it to be present in a restricted number of tissues and failed to find it in the vasculature. Recently, type VIII collagen was shown (using monospecific polyclonal antibodies) to be a component of large blood vessels with predominant localization in the subendothelium. We applied an improved immunofluorescence technique using these antibodies to define the tissue distribution of type VIII collagen. We show that it is a component of arterioles and venules in muscle, heart, kidney, spleen, liver and lung and is also found in connective tissue layers around hair follicles, around nerve bundles in muscle, in the dura of the optic nerve, in cornea and sclera, and in the perichondrium of cartilaginous tissues. This collagen variant appears to have a wider distribution than originally assumed. It is a macromolecular component of the subendothelium, possibly a constituent of the vascular intimal basement membrane.