SECRETORY RESPONSE OF MAST-CELLS CONTAINED IN MONODISPERSED HUMAN CHOROIDAL PREPARATIONS

Background: Mast cells have been identified in the choroid of numerous species including man. However, functional studies involving these hu man mast cells have not been reported. In the current studies, the sec retory response of human choroidal mast cells to various stimuli was e xamined using monodispersed choroidal cell preparations. Methods: Mono dispersed cell suspensions of human choroid were prepared from eye ban k globes and the number, histamine content, and secretory response of mast cells in these preparations were determined. Choroids from 27 don ors were used for these experiments. Results: Cell suspensions contain ed an average of 15% mast cells. Mast cells stained positively with to luidine blue and exhibited the classical granular appearance upon elec tron microscopy. The amount of histamine contained in each mast cell w as calculated to be 2.74 +/- 0.17 pg. Significant histamine release wa s observed following treatment with anti-human IgE, calcium ionophore A(23187), concanavalin A, compound 48/80 and morphine. Conclusion: A m ethod has been developed for obtaining monodispersed human choroidal m ast cell preparations. The cells were functional as evidenced by their ability to release histamine upon immunological and nonimmunological stimulation. The degranulation noted following compound 48/80 and morp hine challenge suggests that these human choroidal mast cells are anal ogous to connective tissue or chymase/tryptase-positive mast cells.