Frequency of CD39+, LAG3+, and CTLA4+ Regulatory T Cells in Two Different Immunosuppressive Protocols in Renal Allograft Recipients (Sirolimus vs Mycophenolate mofetil): A Cohort Report

Background: Impaired renal function is considered as a significant risk factor for cardiovascular events in chronic kidney disease patients. Several immunosuppressive drugs are used in these patients, which necessitates to minimize the drug-related side effects by employing alternative strategies. Objective: This study aimed to evaluate prospectively the influence of low dose ATG induction therapy with two different protocols (Sirolimus versus Mycophenolate mofetil) on the expression of functional markers (LAG-3, CD39, and intracellular CTLA-4) on conventional Tregs in renal recipients. Methods: Thirty-eight renal transplant recipients were enrolled in this study. The patients were randomly assigned into two groups, including TMP: Tacrolimus (Tac), Mycophenolate mofetil (MMF), and Prednisolone (n=23); and TSP: Tac, Sirolimus (SRL), and Prednisolone (n=15). The frequency of LAG-3, CD39, and intracellular CTLA-4 on circulating Tregs was analyzed by flow cytometry before and after transplantation. Results: Analysis of the flow cytometry data showed that the frequency of CD4+CD25+FOXP3+ Tregs increased 4 months post-transplantation compared to pre-transplantation in both groups, although this increase was only significant in TMP group. In TMP treated patients, the frequency of LAG-3+ Tregs and CD39+ Tregs increased, whereas the frequency of intracellular CTLA-4+ Tregs decreased 4 months post-transplantation. In TSP group, while the frequency of CD39+ Tregs increased, the frequency of CTLA-4+ Tregs decreased in post-transplantation compared to pre-transplantation. Conclusions: it seems that both treatment regimen protocols with a low dose ATG induction therapy may be clinically applicable in kidney transplant recipients.