Effect of mast cells on tumor angiogenesis in lung cancer

Background. We conducted a retrospective study to clarify the effect of mast cells on tumor angiogenesis in lung cancer patients. Methods. Formalin-fixed and paraffin-embedded tumor sections were used in this study. Parenchymal mast cells were stained with Alcian blue and safranin O. The number of mast cells per ten fields at a magnification of 200 x was counted under light microscopy, and the average count was determined. To highlight the microvessels, endothelial cells were stained with anti-human factor VIII antibody. After the microvessel count was determined, the microvessels were further stained with Alcian blue and safranin O to show areas of mast cell infiltration. Expression of vascular endothelial growth factor was assessed using a polyclonal antibody. Results. We found a significant correlation between mast cell count and microvessel density. This correlation was also observed in patients with adenocarcinoma (p < 0.001) as well as in patients with squamous cell carcinoma (p < 0.01). Double staining of the microvessels showed highly angiogenic areas densely populated with mast cells. Although we detected a slight trend toward a correlation between vascular endothelial growth factor expression and microvessel density, it was not statistically significant. We found no association between vascular endothelial growth factor expression and mast cell count. Conclusions. There appears to be a direct correlation between the number of mast cells and tumor angiogenesis in patients with lung cancer, and this relationship appears to be independent of vascular endothelial growth factor expression. (C) 2000 by The Society of Thoracic Surgeons.