Tryptase- and leptin-positive mast cells correlate with vascular density in uterine leiomyomas.

In vitro and in vivo studies have linked mast cell (MC) degranulation and activation with angiogenesis and neovascularization. This assumption is partially supported by the close anatomical association between MC and the vasculature and the recruitment of these cells during tumor growth. The aim of this study was to correlate the extent of angiogenesis with the number of MC expressing tryptase and leptin in human leiomyomas. Tissues from human leiomyomas and control specimens were investigated immunohistochemically, using murine monoclonal antibodies against the endothelial cell marker CD31, leptin, and the MC marker tryptase. Angiogenesis, measured as microvessel counts, was highly correlated with MC tryptase- and leptin-positive cell counts. These data suggest that angiogenesis in leiomyomas is correlated to expression of tryptase in MC granules and provide for the first time evidence of a putative role of leptin, also contained in MC secretory granules, in MC-dependent angiogenesis.