Proteoglycan molecules in keratoconus corneas.

Proteoglycan molecules in keratoconus corneas were studied by immunohistochemical and electron microscopic histochemical methods. Compared with normal human control subjects, the staining intensity with monoclonal antibody 9-A-2 was enhanced in the stroma of scarred keratoconus corneas, whereas the intensity with antibody J-19 was reduced. The 9-A-2 experiment showed an increased immunoreactivity of dermatan sulfate proteoglycan epitopes, and the J-19 experiment indicated a decreased immunoreactivity of sulfated keratan sulfate epitopes. Uronic acid analyses were consistent with the 9-A-2 data. Electron microscopy performed after cuprolinic blue staining showed apparent accumulation of abnormally thick, chondroitinase ABC-sensitive, dermatan sulfate proteoglycan filaments in keratoconus corneas. Such filaments were especially prominent in scarred areas. In addition, Keratan sulfate proteoglycan filaments appeared to be less abundant than those found in normal control corneas. Similar alterations of both types of proteoglycan molecules were also seen and reported in scarred corneas. The similarity suggests that the proteoglycan abnormalities found in keratoconus corneas may be secondary, at least in part, to scarring.