Abstract
Purpose:
A multitude of cytokines have been shown to be upregulated at the time of retinal detachment surgery in patients who develop future proliferative vitreoretinopathy (PVR). Analysis of cytologic specimens at this early stage may thus also provide insight into the cellular composition of the pre-clinical stages of PVR. Since cytologic studies often yield inconclusive results due to the use of unreliable morphological criteria, we performed an immunocytological study on cells in subretinal fluid to expand the knowledge on the cellular basis of PVR.
Methods:
Subretinal fluid samples of 33 consecutive cases with retinal detachment were collected during scleral buckling surgery. Samples were immediately centrifuged for 5 minutes at 700 rpm. Pellets from all samples were divided onto four slides per sample by cytospin, air-dried, and stored at -80°C. A scale of cellular density was established for each specimen: low cellularity for <100 cells per slide, intermediate for 100-200 cells per slide, and high for > 200 cells per slide. Slides were immunostained for cytokeratin 8/18 and CD68 (double staining), CD3 and CD20 (double staining), pankeratin, and alpha-smooth muscle actin (SMA).
Results:
Few cells were identified in 13/33 samples (39%). Intermediate and high cellularity were seen in 12/33 (36%) and 8/33 samples (24%), respectively. Pankeratin positive cells were identified in 33/33 (100%) samples investigated, cytokeratin 8/18 positive cells in 19/33 samples (58%), and CD68 positive cells in 31/33 samples (94%). CD3+ cells were seen in one sample (3%), whereas CD20 staining was negative in all samples investigated. Staining for alpha-SMA was positive in 26 samples (79%). Of samples that stained negative for alpha-SMA, 6/7 (86%) had low cellularity. In two samples, few cells double-stained for both cytokeratin 8/18 and CD68.
Conclusions:
These results underline the paradigm that retinal pigment epithelial cells and macrophages may play a pivotal role in the sequelae resulting in PVR membrane formation after retinal detachment. The discrepancy between the number of samples with pankeratin and cytokeratin 8/18 positive cells may be explained by early dedifferentiation of pigment epithelial cells. In line with this, alpha-SMA positivity in the majority of samples may be an early sign of epithelial-mesenchymal transition. Lymphocytes are unlikely to play a role after retinal detachment.
Keywords: 491 cytology •
697 retinal detachment •
655 proliferative vitreoretinopathy