Identification and quantification of transferrin receptors on trabecular cells

The authors identified and quantified the receptor for transferrin on trabecular meshwork (TM) cells cultured from porcine eyes by using two receptor assays. Flow-cytometric analysis of TM cells that were incubated with a monoclonal antibody to the transferrin receptor revealed such receptors, which decreased in number as the cells passed from the pre- to the post-confluent phase. Quantitative characterization by radioligand binding of 125I-transferrin to trabecular cells followed by Scatchard analysis showed that pre-confluent cultures expressed 23,839 +/- 6746 high-affinity receptors/cell and post-confluent cultures expressed 5104 +/- 3639 receptors/cell. The expression of the receptor for transferrin reflects the index of mitotic activity and can be correlated with the proliferative state of the trabecular cells. Further characterization of the receptors for transferrin in the TM may open up the possibility of a pharmacologic approach that enhances the TM cell population, which is known to decrease with age and in glaucomatous states of the eye.