Mast cells in pterygium: Number and phenotype

Purpose: To investigate the pathogenesis of pterygium. Methods: The number and phenotype of mast cells were examined in excised ti ssue from 35 pterygia patients and compared with those in normal conjunctiv al specimens obtained during cataract or other intraocular surgery. Results: Toluidine blue staining showed that the mean number of mast cells in the pterygia specimens was twice as high as that in the normal conjuncti val tissues. Immunohistochemistry with a primary antibody to tryptase, spec ific for mast cells, also revealed a twofold increase in the mast cell numb er in the pterygia specimens compared with the normal conjunctival tissues. In the pterygia, more than 94% of the tryptase-positive mast cells were fo und to express chymase and c-kit. Almost all mast cells in the pterygia wer e tryptase-positive, chymase-positive mast cells (MC(TC)s). There was no ph enotypic difference between the mast cells in the pterygia and those in the normal conjunctival tissues. Conclusions: The MC(TC)s appear not to be immune system-related and to have functions in angiogenesis and tissue remodeling. The increase in the numb; er of mast cells caused by nonallergic stimulation may contribute to the pa thogenesis of pterygium. (C) 1999 Japanese Ophthalmological Society.