Abstract
Abstract: :
Purpose:Ambient light induces microglia to invade the subretinal space of eyes of albino, but not pigmented, mice. We investigated whether the fate of allogeneic neonatal neuronal retina (NNR) grafts placed in the subretinal space (SRS) depends upon the presence and density of subretinal microglia. Methods: 6 wk old BALB/c mice were preconditioned with different light conditions (ranging from 100 - 500 lux) for 2 weeks. NNR grafts prepared from newborn C57BL/6 and BALB/c donors were suspended in 2 µl medium and injected into the SRS via glass needle pipette. Recipients were returned to similar or different light environments. Graft survival was evaluated on a scale of 0 - 5+ by histologic examination of graft-containing eyes extirpated 35 d post-grafting. In some recipients, acquisition of donor-specific delayed hypersensitivity (DH) was assessed. Results: Allogeneic (but not syngeneic) NNR graft survival at 35 days was markedly curtailed (4/14 survived) in recipients placed in bright light conditions after grafting, whereas NNR allograft survival was improved (11/13 survived) in recipients placed in dim light conditions - similar to recipients maintained in conventional light (5/6 survived). Very few recipients acquired donor-specific DH. Conclusion: Bright light, which promotes microglia migration into the SRS, prejudices the survival of allogeneic NNR grafts placed in this site. Immune rejection appears to be motivated by microglia, but not via induction of donor specific delayed hypersensitivity.
Keywords: 607 transplantation • 470 microglia • 384 dark/light adaptation