Immunolocalization of basic fibroblast growth factor, fibroblast growth factor receptor-2, epidermal growth factor receptor and proliferating cell nuclear antigen in pterygia

Purpose. Basic fibroblast growth factor (bFGF) is a potent mitogenic peptide for a variety of cell types. Pterygium is a process in which fibrovascular tissue from the bulbar conjunctiva encroaches onto the cornea. This study was performed to determine if bFGF and its receptor are expressed in pterygia tissues. Epidermal growth factor receptor (EGF-R) was examined for comparison. Methods. Formalin fixed paraffin-embedded tissue samples of pterygia (N=12) were studied immunohistochemically with antibodies to bFGF, bFGF-R2 (bek), EGF-R and proliferating cell nuclear antigen (PCNA). 6 samples were doubled labeled with antibodies to bFGF and tryptase (a mast cell marker) to determine if mast cells are a source of bFGF in pterygia. Results. bFGF was immunolocalized in blood vessels, epithelium, and a subset of mononuclear cells. Strong immunostaining for FGF-R2 was seen in blood vessels and the epithelium. Intense immunostaining for EGF-R was seen in the epithelium but the subepithelial tissue was negative. PCNA was immunolocalized to epithelial cells and some endothelial cells in the subepithelial region. The majority of bFGF positive mononuclear cells were also tryptase positive (90.4±3.6%). Conclusions. These findings suggest that bFGF may contribute to the cellular proliferation in pterygia and mast cells are a source of this growth factor. The EGF-R results suggest that transforming growth factor-α or epidermal growth factor could also contribute to the epithelial cell proliferation in pterygia.