Immunophenotyping of T cell subsets from paired vitreous and peripheral blood samples in human uveitis.

Abstract

Purpose : T lymphocytes play a major role in the immunopathogenesis of most uveitis entities. However, little is known about the intraocular T cell subpopulations in these patients. In this study, we have compared T cell immunophenotypes in paired vitreous and blood samples from different posterior segment uveitis.

Methods : Vitreous infiltrating cells and peripheral blood mononuclear cells (PMBCs) were collected from patients with different infectious and non-infectious uveitis. Specific T cell subset frequencies and cytokine responses to different antigenic stimulations were determined by flow cytometry. Wilcoxon matched pairs signed rank test was used for comparing vitreous and PBMC samples.

Results : Twenty-four paired samples were analyzed. CD3⁺ and CD4⁺ frequencies were comparable, whereas CD8⁺ was lower (p=0.008) and CD4/CD8 ratios were higher (p=0.02) in vitreous samples. Within the CD4⁺ population, memory T cells (CD45RO+, p=0.0067) and resident memory T cells (CD69⁺, p=0.001) were more in the vitreous, but the central memory (CCR7⁺) and effector memory (CCR7^-) subsets were comparable. Pro-inflammatory cytokine responses (TNFα, IFNγ and IL-2) to PMA/ionomycin stimulation were higher in vitreous (p=0.0059; p=0.024; and p=0.002 respectively), among CD4⁺ cells but not among CD8⁺ cells. Similarly, the TNFα, IFNγ and IL-2 responses to interphotoreceptor retinoid binding protein (IRBP) peptide stimulation were significantly higher (p<0.0001; p=0.0005; and p=0.012 respectively) in vitreous CD4⁺ cells, compared to PBMCs. Finally, among tuberculin skin test positive patients (n=23), the TNFα, IFNγ and IL-2 responses to Mycobacterium tuberculosis peptide pool stimulation were significantly higher (p=0.0002; p=0.0005; and p=0.043 respectively) in vitreous CD4⁺ cells, than PBMCs (Fig. 1).

Conclusions : T cell subsets in the investigated cohort of patients were significantly different in the vitreous as compared to blood. CD4⁺ memory T-cells, specifically the resident memory subset, were predominant in the vitreous. Cytokine responses to both ionophore and retinal autoantigen stimulation, as well as to microbial antigens were distinctly higher in the vitreous compared to blood.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1: Cytokine responses to Mycobacterium tuberculosis antigen (ESAT-6 and CFP-10) peptide pools, from paired vitreous and peripheral blood mononuclear cell (PBMC) samples of tuberculin skin test positive patients with uveitis.