MAJOR BASEMENT-MEMBRANE COMPONENTS IN KAPOSIS-SARCOMA, ANGIOSARCOMA AND BENIGN VASCULAR NEOGENESIS

Recent cell biologic studies have emphasized the importance of the bas ement membrane (BM) and its molecular components in angiogenesis. We i mmunostained 60 angioproliferative lesions (angiosarcoma, sclerosing h emangioma of skin, pyogenic granuloma, capillary hemangioma, lymphangi oma, glomangioma ma and granulation tissue) and 23 cases of Kaposi's s arcoma (KS) for the major macromolecular components laminin, collagen type TV, fibronectin and heparan sulfate proteoglycan (HSPG). Normal s tructures served as aggregate controls in each group, and semiquantita tive scoring reflected the degree of consistency of staining about blo od and lymphatic endothelium and vascular sheath (pericyte/smooth musc le) within and peripheral to each lesion. Benign and reactive vasoprol iferations consistently maintained immunoreactivity for each BM compon ent around endothelium and sheath components of blood vessels. Angiosa rcoma showed from 20 to more than 60% less consistent immunoreactivity by comparison, although the score variances were greater than for non -malignant lesions. Staining about blood vessel endothelium was both s trong and consistent among histologic stages in KS with the exception of HSPG, which was weakly immunoreactive in all stages. Marked selecti ve HSPG loss was characteristic only of KS and normal lymphendothelium , and in the light of evidence for a role for HSPG in the assembly and maintenance of BM, suggests that reduced HSPG may be responsible for the loss of ultrastructural integrity of perivascular BM in both.