ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression of fractalkine (FKN) and its receptor CX3CR1 in cardiac allografts and the effect of Cyclosporin A (CsA).</p><p><b>METHODS</b>Three groups of rats underwent heterotopic cardiac transplantation, 45 cases in each group and 5 cases in control group: SD to SD regarded as isograft group (group A), Wistar to SD divided into CsA untreated allograft group (group B) and CsA treated allograft group (group C), normal SD rats as control group. The FKN mRNA expression was detected by one-step RT-PCR method and the expression of FKN and CX3CR1 protein was detected by standard ABC immunohistochemical technique.</p><p><b>RESULTS</b>The expression of FKN mRNA and protein was weak in both isografts and normal heart specimens. The changes of FKN mRNA expression were correlated with the process of acute allograft rejection. The peak of FKN mRNA expression (0.8 +/- 0.26) appeared on the seventh day after transplantation, which could be down-regulated by CsA significantly (t = 2.390, P < 0.05). FKN protein was located in endothelia cells and its receptor CX3CR1 was located in infiltrating mononuclear cells in allografts.</p><p><b>CONCLUSIONS</b>Upregulation of FKN and its receptor was significantly correlated with the trafficking of mononuclear cells which play an important role in acute allograft rejection. It may be one of the important mechanisms of CsA to intervene the acute rejection by inhibiting the activation of the FKN-CX3CR1 pathway.</p>