Introduction & Aim: Kidney transplantation is the best treatment option in end-stage renal disease patients that improve both life quality and allograft survival. Rejection is the major risk factor that limits allograft survival. Transplant biopsy is the critical tool to evaluate the immunological response and risk of rejection in kidney transplant recipients. CD68 positive macrophages have become a commonly used marker to show immune cell infiltration. In our study, we aimed to investigate the relationship between presence of CD68 positive macrophages with rejection and graft survival in biopsies of kidney transplant recipients.
Materials & Methods: In our study, we evaluated the possible relationship between clinical and laboratory parameters with biopsy results, biochemical parameters, immunosuppressive therapies, and CD68 positive macrophages that has been detected in transplant biopsies in 40 kidney transplant recipients who received allograft biopsy between June 2022 and June 2023.
Results: A total of 40 patients (10 female and 30 male, 25% and 75% respectively) had a mean age of 39,90 ± 15,43 years has been included to our study. Mean duration from transplantation to biopsy date was 85,25 ±108,19 months. When we compared the pre and post-transplant parameters, serum creatinine levels has been significantly decreased after immunosuppressive treatment(p<0.05). The increase in number of CD68 positive macrophages have been shown to be associated with both acute cellular rejection (p<0.007) and antibody mediated rejection (p<0.02) and also with TMA (p<0.15). Kidney transplant recipients had a high rate of sclerosis (23%) and has a mean duration of over 7 years after transplantation and because of the role of macrophages in both chronicity and cleaning role in kidney injury, it is not surprising to see higher numbers of macrophages in kidney transplant biopsy series. Increase of the number of CD68 positive macrophages in glomeruli are found to be significantly associated with both global sclerosis and acute rejection episodes. This association may be explained with the fact that global sclerosis is a part of chronic process. In this chronic process, it is natural for the CD68 positive macrophages to be involved in the rejection. The higher results of both serum creatinine and protein to creatinine ratio in spot urinary sample are also supporting this hypothesis. Limited number of the sample is a disadvantage for our study.
Conclusion: Macrophages are important immune system cells who have a central role in both acute and chronic rejection episodes. In our study, we showed that increase of number of CD68 positive macrophage in allograft biopsies is significantly associated with cellular rejection, antibody mediated rejection and trombotic microangiopathy. This study shows that the therapies that are targeting macrophage regulation primarily and immuno-modulation of macrophages are needed in allograft rejection strategies.