USE OF THE MIB-1 ANTIBODY FOR DETECTING PROLIFERATING CELLS IN THE RETINA

Purpose. To study intraretinal proliferation as a response to experime ntal retinal detachment using an antibody that recognizes the nuclear specific antigen Ki-67 in proliferating cells. Methods. Experimental r etinal detachments were produced in cats (1, 3, 7, and 28 days) and ra bbits (1, 3, and 7 days). The animals were killed and the eyes were fi xed and embedded in paraffin. Histologic sections were processed for i mmunohistochemistry using the MIB-1 antibody to detect the Ki-67 prote in. Labeled cells were identified, and the proliferative response was quantified. Results. In normal cat retina, approximately 0.05 cells pe r millimeter of retina are labeled. In cat retina detached for 1, 3, 7 , or 28 days, the number of cells labeled by MIB-1 is 0.06, 5.03, 1.38 , and 0.23 cells per millimeter of retina, respectively. MIB-1 labelin g yields an approximate fivefold increase over the number of prolifera ting cells detected in retinal sections using H-3-thymidine autoradiog raphy. Detachment of the rabbit retina elicits a similar response as m easured by MIB-1 immunohistochemistry. Conclusions. In contrast to H-3 -thymidine, which labels cells in S-phase only, the MIB-1 antibody lab els proliferating cells regardless of their location within the cell c ycle. MIB-1 labeling, therefore, is a more accurate means of evaluatin g cellular proliferation in the retina and elsewhere in the central ne rvous system, and it is a relatively simple way of evaluating the effe cts of agents that may affect this response.