Background: To investigate the potential contribution of immune-mediated processes to the development of proliferative diabetic retinopathy (PDR), an immunohistochemical study was undertaken to characterize the infiltrating immune cells in epiretinal membranes from the eyes of patients with PDR.
Methods: A total of 18 PDR epiretinal membrane specimens obtained surgically from pars plana vitrectomy were studied by using a panel of monoclonal antibodies against T lymphocytes (CD4 and CD8), interleukin-2 (IL-2) and interleukin-2 receptors (IL-2R).
Results: Twelve of 18 specimens (67%) contained CD4-positive cells and 13 of 18 (73%) contained CD8-positive cells. IL-2 was found in 12 of 18 samples (67%), of which 11 also contained CD4-positive cells, and IL-2R was detected in 10 of 18 membranes (56%), of which 9 contained CD4-positive cells and released IL-2. Most of the IL-2R-positive membranes were from type I diabetic patients, 40% of them from patients younger than 40 years.
Conclusion: Our study demonstrated the involvement of activated immune cells and release of lymphokine(s) in more than half of the diabetic epiretinal membranes tested and revealed that the processes of immune responses and the biological effects of lymphokine(s) may play an important part in the development of epiretinal membranes of PDR, especially in young-onset and type I diabetes.