Abstract
Purpose: :
We have previously described a model to study T cell migration in inflamed cornea and reported possible interactions between T cells and antigen–presenting cells (APCs). Here we use a slightly modified version of that model to explore interactions between T cells and resident APCs, specifically those bearing major histocompatibility complex class II (IAd) surface molecules, in the central cornea.
Methods: :
Chicken ovalbumin (OVA)–specific T cells, isolated from DO11.10 mouse spleens, were cultured with OVA(323–329) peptide, labeled with CMTMR (orange) and adoptively transferred into 6 naïve BALB/c mice. Animals were challenged 1–2d later with a single corneal intrastromal injection (1µL) of a mix of AlexaFluor 488–labeled (green) anti–IAd antibody (0.5mg/mL), OVA (17mg/mL) and P. aeruginosa lipopolysaccharide (3mg/mL). Real–time images of central corneal cells at 6, 24 and 48h post–challenge were collected with an intravital fluorescence microscope and quantified by a masked observer. At 24 and 48 h time–lapse intravital imaging (30–min duration) was performed in the central corneas of 3 mice. Movies were processed with image stabilization software (Media Cybernetics) and movement of T cells in relation to resident IAd+ cells was characterized by closest proximity between T and IAd+ cells. Cells were either in definite contact, proximal (<1 T cell diameter apart) or solitary (>1 T cell diameter apart).
Results: :
Since T cell infiltration into cornea was minimal at 6h, only 24 and 48h data were analyzed. At 24h, real time scans showed an average of 18.5 T cells/mm2, with 27.9% proximal/contacting IAd+ cells, and an average of 68.7 IAd+ cells/mm2, with 8.6% proximal/contacting T cells. At 48h more T cells were present with an average of 32 T cells/mm2, with 32.8% proximal/contacting IAd+ cells, and an average of 98.9 IAd+ cells/mm2, with 10.3% proximal/contacting T cells. Migration of T cells was evident in time–lapse videos and IAd+ cell migration was substantially slower than T cell migration. Some T cells were seen to move toward or away from IAd+ cells whereas others remained near IAd+ cells or solitary during the recording. This resulted in 46% and 65% of the T cells being in contact or close proximity to IAd+ cells at some point during the recordings at 24 and 48h time points, respectively.
Conclusions: :
CD4+ T cells and APCs have prolonged contact in non–lymphoid tissue with some similarity to interactions seen in lymphoid tissues. These interactions are presumably critical to understanding T cell and APC function in the cornea.
Keywords: cornea: basic science • antigen presentation/processing • imaging/image analysis: non-clinical