Modulatory effect of sera from sarcoidosis patients on mononuclear cell-induced angiogenesis

Sarcoidosis (SAR) is a systemic granulomatous inflammatory disease characterized by recruitment and activation of peripheral blood mononuclear cells to the sites of disease. Neovascularisation is a principal vascular response in chronic inflammation and hypoxia. The aim of the study was to evaluate the effect of sera from sarcoidosis patients on angiogenic capability of different subsets of normal peripheral human mononuclear cells (MNC) in relation to IL-6 and IL-8 serum levels, to radiological stages of disease and to the presence of extrapulmonary changes. Serum samples obtained from 42 sarcoidosis patients were examined. There were 12 patients in stage I, 16 patients in stage II, and 14 in stage III. In order to quantify angiogenesis, a leukocyte-induced angiogenesis assay was performed by a method of Sidky and Auerbach. MNC were depleted in monocytes by glass adherence and phagocytosis of iron particles techniques. IL-6 and IL-8 in sera from sarcoidosis patients were evaluated by an ELISA-based assay. Sera from sarcoidosis patients enhanced angiogenic capability of normal MNC significantly stronger than sera from healthy donors (P<0.001). Angiogenic activity of sera in sarcoidosis depended on the stage of disease and appeared most pronounced in stage II (P<0.05). Sera from patients with extrapulmonary changes exerted stronger effect on angiogenesis than sera from patients with thoracic changes only (P<0.001). IL-6 and IL-8 serum level correlated with each other, but no correlation was found between IL-6 and IL-8 serum level and angiogenic activity of the examined sera. Removal of monocytes from MNC eliminated the effect of sera from sarcoidosis patients on angiogenesis compared with the effect of these sera on intact MNC (P<0.001). Sera from sarcoidosis patients and from healthy people constitute a source of mediators participating in angiogenesis. Sera from sarcoidosis patients prime monocytes for production of proangiogenic factors.