TRANSFERRIN PRODUCTION BY THE CILIARY BODY OF RABBITS - A BIOCHEMICALAND IMMUNOCYTOCHEMICAL STUDY

Purpose. We have previously reported that transferrin is one of severa l glycoproteins synthesized within the eye and secreted into the vitre ous. The present investigation was designed to determine the role of t he ciliary body in the production of this vitreous transferrin. Method s. Isolated ciliary body-iris were incubated with H-3-fucose, H-3-tyro sine or S-35-methionine and afterwards the culture media were processe d for affinity chromatography using columns of Sepharose conjugated wi th antibody to rabbit plasma transferrin. Reverse transcription-polime rase chain reaction (RT-PCR) was carried out using total RNA extracted from fresh ciliary body-iris and primers constructed on the basis of the known sequence of transferrin mRNA from rabbit liver. The fragment obtained was employed as a probe in northern-blots of total RNA of ci liary body-iris. Furthermore, paraffin sections of eyes were treated f or immunocytochemical visualization of transferrin. Results. A labeled polypeptide, specifically eluted from the antitransferrin columns, wa s detected in the incubation medium, transferrin mRNA was found in ext racts of whole ciliary body-iris, and transferrin antigenicity was ide ntified in the ciliary and iridial epithelial cells by immunocytochemi stry. Conclusions. These results demonstrate the ciliary epithelium as one of the sources of the vitreous transferrin.