Abstract
Purpose:
In the last years immune activities of destructive nature were detected in retina of glaucoma patients. Evidence of T-cell activities was noted in blood of patients. These immune cells can act via pro-apoptotic cytokines, which are great contributors in the mechanism of cell death. In order to investigate the role of T-cells in a glaucomatous model we detected cells and we looked at the cytokines to define the T-cell status.
Methods:
Rats were immunized with optic nerve homogenate antigen (ONA, n=6) or NaCl (Co, n=6). Over a 4 week period the intraocular pressure (IOP) was measured in ONA and Co group. 14 days post immunization (p.i.) the CD3+ T-cell number was measured in the retina with a Cyflow FACS and the groups were compared to a shame immunized group (Naïve: n=6). At 28 days cryo-cross sections of the eyes were stained with Brn-3a in combination with CD3, TNF-α or FasL. The serum TNF-α concentration was measured with an ELISA Kit. Groups were compared with student t-test.
Results:
IOP remained constant in Co and ONA (p=0.4) group throughout the project. 28 days p.i. the retinal ganglion cell (RGC) density of the immunized group decreased compared with Co (Co: 5±3.3/section; ONA: 3.6±2.5/section, p=0.001). In comparison with the Naïve group the retinal CD3+ T-cell number increased significantly in the ONA group (p=0.04) after 14 days. 28 days p.i. no T-cells and hardly any TNF-α signal were detected in the retinae of Co and ONA. In the serum of both groups the TNF-α concentration is extremely low, with no differences between the groups. For this reason the concentration wasn't detectable with the ELISA at the point of time 4 weeks p.i.. The FasL signal was quantifiable in all retina layers, but no significant differences between the groups were noted (Co: 15.6±9.2; ONA 9.7±4.6, p=0.4) at 4 weeks.
Conclusions:
In the ONA group the RGC loss increases significantly without an elevation of the IOP after 28 days. While the ONA animals displayed a slight T-cell infiltration in the retina at 14 days, no T-cell activities were detectable at 28 days. The T-cell effect seems to be an early event, because the 28 days hardly any T-cell dependent immune activities were noted: no CD3+ signal in the retina, no sign for retinal and systemic TNF-α, and no changes in retinal FasL formation. The antigen ONA seems to have a time dependent influence to the immune mechanism of T-cells.
Keywords: 695 retinal degenerations: cell biology •
529 flow cytometry •
555 immunomodulation/immunoregulation