Immunolocalization of an angiogenic factor (HAF) in normal, inflammatory and tumor tissues

The distribution of a novel human angiogenic factor (HAF) (Schulze Osthoff et al., 1987) has been investigated on various human cell lines, isolated blood cells as well as in normal, inflammatory and tumor tissues. Localization was performed by using the monoclonal antibody (MAb) 5F4 directed against HAF. It was found that 30% of freshly isolated human monocytes expressed the 5F4 antigen. The number of positive cells increased to 75-90% on day 4 to 7 upon culture and then decreased. Twenty percent of freshly isolated human lymphocytes also stained positively, whereas granulocytes and platelets were negative. In cryostat sections of normal human tissue (skin, lung, liver, spleen, placenta) 5F4 is positive with capillary endothelial cells and few macrophages. In inflammatory tissue derived from gingivitis and rheumatoid arthritis, more macrophages than in normal tissues and less endothelial cells were positive. In tumor tissues some endothelial cells and a subset of tumor-infiltrating macrophages expressed the antigen. Tumor cells were positive in advanced melanomas, but only occasionally in stomach carcinomas. We conclude that the angiogenic factor is produced mainly by a subset of inflammatory macrophages which appear to be the principal source of HAF in regenerating or growing tissues.