Related Experiment Videos
Hematopoietically derived retinal perivascular microglia initiate uveoretinitis in experimental autoimmune uveitis
V K Gullapalli1, J Zhang, G Pararajasegaram
1Department of Ophthalmology, University of Southern California School of Medicine, Los Angeles 90033, USA.
Background:
Hematopoietically derived cells in the retina were studied for the expression of molecules associated with antigen presentation.
Methods:
Bone marrow cells of (Lewis x Brown Norway) F1 rats (LBNF1) were transplanted to sublethally irradiated Brown Norway (BN) rats to construct chimeric rats (LBNF-->BN). Each of 21 established chimeras received an adoptive transfer of uveitogenic Lewis T lymphocytes. Three rats were killed on each of 7 consecutive days. The right eye of each rat was processed for flat-mount preparation of the retina; the left eye of each was frozen for cryostat sectioning. All tissues were then stained with one of the following antibodies: OX-3 (Lewis-specific MHC class II marker), anti-ICAM, anti-B7- 1, anti-TNF-alpha or anti-IL-1beta.
Results:
Initial clinical signs of EAU appeared first on day 4; by day 6, full-blown EAU was noted. The flatmount preparations revealed the presence of OX-3+ cells in the retina, perivascularly exhibiting dendritic morphology on day 2. These cells were observed in the retinal nerve fiber layer (NFL). No B7-1+, ICAM-1+, TNF-alpha+ or IL-1beta + cells were detected. Cryostat sections revealed positive cell staining of perivascular microglia and astrocytes in the retinal NFL with anti-IL-1beta and anti-TNF-alpha antibodies.
Conclusions:
Since only perivascular bone marrow-derived cells are seen to express MHC class II molecules prior to onset of EAU, and since these cells also generate the cytokines IL- 1beta and TNF-alpha, it appears that initial presentation of antigen in the retina could be by these cells.