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M. B. Ronick, D. Choi, S. R. Planck, J. T. Rosenbaum; OVA-Specific T Cells Appear to Interact With Antigen-Presenting Cells (APCs) Loaded With Either OVA or Irrelevant Protein in the Inflamed Murine Iris. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2631.
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© ARVO (1962-2015); The Authors (2016-present)
We employed intravital microscopy to monitor the antigen specificity of T cell-APC interactions in the inflamed murine iris.
OVA peptide-specific T cells from spleens of DO11.10 transgenic mice were cultured with OVA323-329 peptide, stained with CMTMR and injected IV into naïve BALB/c mice. After 2-3 days, the mice were injected intravitreally with 0.5 µg/4 µl E. coli strain 055:B5 endotoxin plus either 100 µg AlexaFluor488 (green)-conjugated ovalbumin or green-Bovine Serum Albumin (BSA). The peak of iris T cell inflammation occurs 24 hrs after antigen injection and by that timepoint the OVA has also been taken up by cells with dendritiform morphology. These cells have previously been characterized as largely MHC class II, F4/80, and CD11c+. At this time, labeled cells were recorded by time-lapse epifluorescent videomicroscopy of irises in anesthetized mice for up to 4 hours. A masked quantifier recorded the duration of probable T cell-APC interactions as the time that a T cell and a protein-loaded APC were within one T cell diameter of one another. A total of 42 T cells in 7 OVA-injected mice and 24 T cells in 10 BSA-injected mice were analyzed.
T cells moved toward and formed reversible interactions with APCs for varying lengths of time (range: <5-110 min). When BSA was injected, fewer DO11.10 T cells infiltrated the iris stroma but the proportion that interacted with labeled APCs was not significantly different compared to OVA-injected eyes (p=0.29). The majority of DO11.10 cells interacted with at least one APC (71% in OVA-injected eyes, 58% in BSA-injected eyes) and several T cells interacted with multiple APCs. Many DO11.10 cells maintained contact with a single APC throughout the entire imaging period (33% in OVA-injected eyes, 25% in BSA-injected eyes). The difference in T cell speed was not significant between the groups (1.6±0.3 (mean±SEM) and 1.3±0.1 µm/min for OVA and BSA-injected animals, respectively).
Although the presence of an antigen recognized by T cells markedly increases the number of infiltrating T cells, APCs bearing irrelevant antigen also frequently interact with T cells in an inflamed iris. Further analysis of the T cell-APC interactions should lead to insights related to antigen-specific responses in nonlymphoid tissues.
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