Immunohistochemical investigation of collagen subtypes in human glioblastomas

The immunohistochemical distribution of a spectrum of collagens and procollagens was studied in 16 glioblastomas. Anti-collagen IV antibodies frequently outlined thickened or disrupted basement membranes (BM) of tumour vessels. Glial BM were frequently penetrated by tumour cells; endothelial BM were not. Some proliferating vessels did not stain for extracellular collagen IV but were rimmed by collagen IV-positive cells, some of which expressed GFAP. Procollagen I was restricted to proliferating leptomeninges and pathological tumour vessels. Collagen III and procollagen III were codistributed in intratumoural and extratumoural interstitial connective tissue. Collagen VI was most pronounced in the adventitia of normal vessels and in spindle-cell proliferations of pathological vessels but not in the endothelial cell proliferations. On the basis of our findings, we conclude that glial cells play a major role in BM formation around tumour vessels, that procollagen I may serve as a marker for proliferation of interstitial connective tissue, and that the origin of spindle-cell proliferation is adventitial, rather than endothelial.