Aqueous Humour Alloreactive Cell Phenotypes, Cytokines and Chemokines in Human Corneal Allograft Rejection

Abstract

Purpose: : Almost all information on the early cellular and molecular changes in corneal allograft rejection is from animal models. The aims of this study were to examine the phenotype of alloreactive cells present in the human anterior chamber and to quantify aqueous humour levels of cytokines and chemokines following onset of endothelial corneal graft rejection

Methods: : Aqueous and peripheral blood samples were taken from patients with endothelial graft rejection (n=11) and from control patients undergoing cataract surgery (n=8). Aqueous cells and supernatants were separated as were peripheral blood cells and sera. Aqueous and peripheral blood cells were stained with fluorochrome-conjugated antibodies to CD45, CD4, CD8 and CD14 (and isotype-matched controls) and analysed by flow cytometry. Aqueous supernatants and sera were analysed by cytometric bead array.

Results: : CD45⁺CD4⁺, CD45⁺CD8⁺ and CD45⁺CD14⁺ cells were found in aqueous samples during rejection; no CD45⁺ cells were seen in control samples. Significantly higher proportions of CD45⁺ cells found in aqueous during rejection were CD14⁺, denoting monocyte / macrophage lineage, than CD4⁺ or CD8⁺. Large and statistically significant elevations were seen in aqueous levels of IL-6, MCP-1 and IP-10 during rejection compared with controls; smaller but still statistically significant increases were seen in Mip-1α and eotaxin.

Conclusions: : Selective recruitment of CD14+, CD4+ and CD8+ cells occurs in endothelial graft rejection. Further studies are needed to establish the functional role of CD14+ cells in the effector component of the allogeneic response and the potential of these chemokines and their receptors as therapeutic targets to prevent graft rejection. Aqueous humour samples from the anterior chamber offer a unique opportunity to analyse components of the allogeneic response that are in direct contact with donor tissue and without the artefacts inherent in examination of tissue.

Keywords: cornea: basic science • immune tolerance/privilege • cytokines/chemokines