The distribution of LH39 basement membrane epitope in the tumour stroma of oral squamous cell carcinomas

LH39 monoclonal antibody detects a novel component of epithelial and endothelial basement membranes. The expression of LH39 antigen was investigated by immunohistochemistry in 55 oral squamous cell carcinomas and compared with 15 pyogenic granulomas of skin and oral mucosa, 20 non-specific oral ulcers, and 20 specimens of normal oral mucosa. The distribution of this basement membrane epitope was compared with that of other basement membrane components, type IV collagen, and laminin. LH39 monoclonal antibody labelled basement membrane surrounding small blood vessels in normal human organs. In oral squamous cell carcinomas, in contrast to the other basement membrane antigens, the LH39 epitope was not detectable in vessels within histologically recognizable tumour stroma. Neovascularization is known to attend malignant neoplasms and this finding was interpreted as absence of LH39 antigen within newly formed vessels. In support of this hypothesis, LH39 immunoreactivity was absent in newly formed blood vessels within pyogenic granulomas and the granulation tissue within ulcers. As increasing neovascularization is reported to correlate with a rising rate of metastasis, assessment of tumour angiogenesis may be of value in selecting patients for initial aggressive therapy.