Proliferative activity in epiretinal membranes. The use of the monoclonal antibody Ki-67 in proliferative vitreoretinal diseases.

Epiretinal membranes occur in a number of pathogenetically different diseases, such as proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy (PDR), macular pucker, and ischemic, inflammatory, and degenerative vitreoretinal disorders. The formation of epiretinal membranes is characterized by the proliferation of histogenetically different cell types. Knowledge of the proliferating potential of surgically excised epiretinal membrane tissue might be clinically relevant to determine which patients face a high risk of recurrences. The monoclonal antibody Ki-67 specifically stains a cell-cycle associated nuclear antigen that is only expressed by cells in the G1, S, and G2/M phases of the cell cycle. With this antibody, the actively proliferating growth fraction can be stained in frozen tissue samples of surgically removed epiretinal membranes by the indirect immunoperoxidase method. In this study, the monoclonal antibody Ki-67 was used to screen 37 epiretinal membranes in PVR, PDR, macular pucker, and in recurrences after intraocular silicone oil tamponade for the presence of actively proliferating cells. Additionally, the number of Ki-67 positive cells in a section of the membrane was quantitatively set in relation to the total cell number of this section. Thus a proliferative index (PI) was ascribed to each membrane as a decimal quotient. The proliferative indices can be graded into four subgroups for missing or very low (PI less than 0.1), low (PI 0.1-0.3), moderate (PI 0.3-0.6), and high (PI greater than 0.6) proliferative activities. High proliferative activities were found in 4 of 5 PVR membranes, in 9 of 14 PDR membranes, in 6 of 11 recurrent membranes after intraocular silicone oil tamponade, and in 2 of 6 macular pucker membranes.(ABSTRACT TRUNCATED AT 250 WORDS)