Objectives: To investigate CD4-CD8 and CD28 expression in T cells infiltrating the vitreous fluid in patients with proliferative diabetic retinopathy and to evaluate the relationship between the infiltrating T cells and both the activity of proliferative diabetic retinopathy and the clinical outcome.
Methods: Both vitreous and peripheral blood samples were obtained simultaneously from 20 consecutive diabetic patients and analyzed by flow cytometry. Three diabetic patients were excluded because there were no viable cells in the vitreous fluid. Six nondiabetic patients requiring vitrectomy were also studied.
Results: T lymphocytes were detected in all 6 diabetic patients with vitreous hemorrhage and in 6 (55%) of the 11 diabetic patients without vitreous hemorrhage, but in none of the nondiabetic patients. The percentages of T cells (CD3+), TCD4+ (CD3+ CD4+), and TCD8+ (CD3+ CD8+) subsets, as well as the expression of CD28, were similar in the vitreous fluid and in the peripheral blood in patients with vitreous hemorrhage. However, in patients without vitreous hemorrhage, the percentage of CD4+ CD28-T cells in the vitreous fluid was significantly higher than in the peripheral blood (33.34% [20.75%-100.00%] vs 8.45% [2.43%-56.59%]; P =.02). In addition, all of these patients showed quiescent retinopathy and their outcome was better than that of patients with vitreous hemorrhage and patients in whom intravitreous T cells were undetectable.
Conclusion: T cells infiltrating the vitreous of diabetic patients without vitreous hemorrhage not only show a different pattern than in the peripheral blood but also seem to improve the prognosis of proliferative diabetic retinopathy.
Clinical relevance: Our results provide further understanding of events involved in the autoimmune response in diabetic retinopathy and may aid in the research for new treatment approaches.