Endothelial Cells Do Not Regulate Expression of CD46, CD55 and CD59 in the Presence of Anti-HLA Class I and II Antibodies

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Conference Proceeding

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Am J Transplant


Purpose: Anti-HLA antibodies, both pre-formed and de novo are associated with worse graft survival. Complement activation is an important mechanism of antibody mediated immunological injury. We hypothesised that anti-HLA antibodies may differentially induce expression of complement regulatory proteins thus resulting in differential injury. Methods: Human primary renal glomerular endothelial cells (HRGEC) were HLA typed. Cells at passage 3-6, were stimulated with Gamma Interferon for 48hours. Cells were then exposed to sera with cell HLA specific anti-HLA class I, Class II and Class I+n antibodies in separate experiments. Sera with no antibodies acted as a negative control. Expression of mRNA for CD46, CD55, and CD59 were studied by qPCR for all these 4 conditions. Cell lysates collected for Western blot and Flow cytometry were also studied for all the 4 conditions. Results: mRNA isolated from endothelial cells, was quantified for CD46, CD55 and CD59 expression by qPCR and there was no difference in expression levels after 48hours under 4 conditions. There was also no difference in surface expression of CD46, CD55 and CD59 by western blot. In the Figure la overlay graph CD46 expression is not altered under 3 different conditions compared to negative control. Similar findings are presented for CD55 and CD59 expression in Figures lb and lc respectively. Conclusions: In these experiments, we clearly show that CD46, CD55 and CD59 expression on renal glomerular endothelial cells do not change in the presence of anti-HLA Z antibodies. Different susceptibility of anti HLA class l and class II anti-bodies are not explained by this mechanism. Upregulation of these underutilized targets may confer additional endothelial protection in the presence of antibodies, especially if the immune-mediated damage is related to complement activation.



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