Comparison of aqueous and vitreous lymphocyte populations from two rat models of experimental uveitis

Abstract

PURPOSE. To compare lymphocyte populations present within inflamed eyes in two rat models of autoimmune uveitis. METHODS. Experimental autoimmune uveitis (EAU) and primed mycobacterial uveitis (PMU) were initiated in Lewis rats. Aqueous and vitreous were collected at peak inflammation (PMU at day 2, EAU at day 14). The number of cells in the aqueous and vitreous was determined and compared for each eye and between the two models. Intraocular CD-19 + B cells, CD3 + T cells, and CD4 + or CD8 + T-cell subpopulations were identified by flow cytometry and compared between EAU and PMU. RESULTS. The median number of cells/mL collected from PMU aqueous (7.98 × 10 7 cells/mL), was not significantly different from the number of cells collected from EAU aqueous (1.61 × 10 7 cells/mL, P = 0.94). EAU aqueous contains a significantly larger mononuclear population (median 61%, interquartile range [IQR] 44%–67%) than PMU (median 9%, IQR 8%–10% [P < 0.0001]). Within the mononuclear population, EAU and PMU aqueous demonstrate similar proportions of CD3 + , CD4 + T cells. However, EAU has a larger CD3 + , CD8 + , T-cell population than PMU, and this population also demonstrates co-expression of CD45R. B cells comprise a significantly larger median percentage of cells in EAU aqueous (median 18%, IQR 15%–20%) compared to PMU (median 13%, IQR 9%–15%, P = 0.006). CONCLUSIONS. Flow cytometry analysis of intraocular lymphocytes from EAU and PMU identifies similarities and differences between the T-cell and B-cell populations present at peak inflammation. Complementary animal models that have well-defined mechanistic differences will improve our ability to test potential new therapies and bring meaningful advances into clinical practice for patients with uveitis.