Abstract

P 150

NK cell depletion delays corneal allograft rejection in baby rats

Simona Schlereth, Johannes Schwartzkopff, Laura Bredow, Christian Jarsch, Moritz Berger, Daniel Böhringer, Thomas Reinhard
Universitäts-Augenklinik Freiburg

Objective
Keratoplasty in children has a very poor prognosis due to a high rejection rate. In an animal model of keratoplasty it was previously shown that young Lewis rats reject a transplant faster than adult animals. These grafts show a stronger infiltration with natural killer (NK) cells than the adult rats. In this set of experiments the role of NK cells during allograft failure in baby rats was studied.
Methods
NK cell depletion was achieved by repeated intraperitoneal injection of a monoclonal antibody (clone 3.2.3). Depletion was controlled by FACS analyses. Allogenic corneal transplantation was performed using Fisher rats as donors and Lewis rats as recipients (3 vs. 10 weeks of age). Opacity was clinically assessed every third day after keratoplasty. Rejection was defined as complete graft opacification. Immunohistochemical analyses of infiltating leukocytes was performed on the day of rejection (CD4, CD8, CD25, CD161, CD 163, and OX62).
Results
Systemic administration of 3.2.3 monoclonal antibodies resulted in a systemic absence of NK cells without affecting the T cell pool. NK cell depletion resulted in a significant delay of corneal allograft failure in 3 week old recipient rats (p<0,01). No differences in infiltrating leukocytes were observed histologically (except for CD161+ NK cells). 
Conclusions
Depletion of NK cells delays allograft rejection in baby rats. This finding underlines their role during corneal allograft rejection in baby rats and is one more step towards understanding the reasons for accelerated corneal graft rejection in infant recipients. However, aside from NK cell other mechanisms seem to contribute to corneal allograft failure in the baby rat.

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