Effective chemokines and cytokines in the rejection of human retinal pigment epithelium (RPE) cell grafts

Objective. In the rejection of transplanted retinal pigment epithelium (RPE ) cells, an activation of allografts is probably the pivotal point for long -term success. The detailed immunological interactions involved in the reje ction after RPE transplantation are still unknown. The aim of this study is to evaluate the interactions of pro-inflammatory cytokines and chemokines in this activation process in vitro. Methods. Human RPE cells (2 x 10(5)/ml) were therefore activated through a pre-treatment with different concentrations of interferon (IFN)-gamma (100 or 1000 U/ml), tumour necrosis factor (TNF)-alpha (1 or 10 ng/ml) or combin ations of both, or employed in a nonactivated form. Afterwards, the RPE cel ls were tested by enzyme-linked immunosorbant assay (ELISA) and ribonucleas e protection assays (RPA) for the secretion and mRNA content of the differe nt chemokines (RANTES, MCP-1 and IL-8) and cytokines (IL-6) at various time points up to 48 h. Main findings. HRPE cells secrete the investigated cytokines In response to pro-inflammatory activation. This could be demonstrated at both the mRNA ( RPA) and the protein levels (ELISA). The secretion was time and dose depend ent, and significantly upregulated in comparison to that observed with nona ctivated cells. Conclusions. This study demonstrates that RPE cells efficiently secrete suc h cytokines as RANTES, MCP-1, IL-6, and IL-8, and have an accountable neutr ophil and monocyte chemotactic activity. Thus, it could be indicated that t he investigated cytokines play a central role in the activation cascade of RPE and in RPE rejection as well.