MIRAgel: the immunohistochemical expression of CD3, CD34, and CD68 in the surrounding capsule.

PurposeTo study the immunohistochemical features of the capsule tissue surrounding MIRAgel episcleral buckles.Patients and methodsThis Institutional interventional clinical cohort study examined a consecutive series of 21 referred patients who required MIRAgel removal from July 2009 to July 2013. All patients with hydrated and fragmented MIRAgel episcleral buckles were included in this study. Capsule biopsies from MIRAgel episcleral buckles were obtained from all patients. Capsule specimens of seven patients with extruded silicone bands were processed as controls. Paraffin-embedded specimens were examined using light microscopy and immunohistochemistry (via the PAP horseradish peroxidase technique) to detect the expression of CD3, CD20, CD34 and CD68, and S-100 protein.ResultsInflammation with granuloma, which was primarily related to sutures, was found in all (n=36) of the MIRAgel specimens and foreign body granulomas with multinucleated giant cells, histiocytes, and macrophages (CD68+ cells) surrounded the MIRAgel fragments. Average number of CD68+ cells was higher (P<0.001) for MIRAgel than for silicone rubber. The lymphocytic inflammatory infiltrate related to the MIRAgel fragments was CD3+ and CD20- (delayed T cell-mediated immune response). Moderate neoangiogenesis was indicated by the presence of CD34+ cells.ConclusionsThe immunohistochemical analysis revealed that the immune system is able to identify the fragments of MIRAgel (after its hydrolytic degradation) as a foreign body during a delayed T cell-mediated immune response. The phagocytosis by macrophages likely triggers and perpetuates local disease. Removal of MIRAgel explants before hydrolysis should be considered.