SECRETION OF PLASMINOGEN ACTIVATORS BY CELLS CULTURED FROM SUBRETINALFLUID

Secretion of plasminogen activators was examined in 11 cells cultures from subretinal fluid of patients with retinal detachment. The plasmin ogen activator production was compared to 4 retinal pigment epithelial cell cultures from post-mortem donors with no known retinal pathology . Plasminogen activator activity was evaluated by zymography and was c orrected for the total cell protein in the cultures. Cells from subret inal fluid had more proteolytic activity and secreted more active urok inase-type plasminogen activator than retinal pigment epithelial cells of donor origin. It is possible that cells from subretinal fluid are modulated by the conditions in subretinal fluid to secrete more urokin ase-type plasminogen activator, generally considered to be a sign of i nvasive growth or that the subretinal fluid cultures contain other cel l types than solely retinal pigment epithelial cells, such as pigmente d macrophages, with an active plasminogen activator production. Altern atively, retinal pigment epithelial cells detached into the subretinal fluid may represent a selected population of retinal pigment epitheli al cells with a more active extracellular proteolysis.