The Association Between Viral Infections and Co-stimulatory Gene Polymorphisms in Kidney Transplant Outcomes

BACKGROUND The surveillance of kidney transplant patients depends on function of different immunologic markers like co-stimulatory molecules. These molecules may also be associated with post kidney transplant viral related outcomes. OBJECTIVES The aim of this study was to investigate the possible associations between co-stimulatory molecule gene polymorphisms and viral infections in kidney transplant patients. PATIENTS AND METHODS In total, 172 kidney transplant patients were included in this study. Single nucleotide polymorphisms in loci of co-stimulatory molecules including: PDCD.1, CD28, CTLA4 and ICOS, were analyzed in the studied patients by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. Active Cytomegalovirus (CMV) infection and history of hepatitis C virus (HCV) infection were analyzed in each kidney transplant patient using the CMV antigenemia kit and HCV antibody assay, according to the manufacturer's instructions. RESULTS CMV active infection was found in 31 of 172 (18.02%) kidney transplant patients. HCV infection was only found in two of the 172 (1.16%) studied patients. Significant associations were found between TT and TC genotypes of CTLA4 -1722T/C and T allele with acute rejection in CMV infected kidney transplant patients. A significant association was also found between the T allele of CD28 + 17 C/T genetic polymorphism and acute rejection in CMV infected kidney transplant patients. Significantly higher frequency of AA genotype and A allele of CTLA4 + 49AG polymorphism were found in CMV infected female patients. Also a significantly higher frequency of GG genotype and G allele of PDCD-1.3A/G polymorphisms were found in CMV infected female patients. CONCLUSIONS Based on these results, CTLA4 and CD28 genetic polymorphisms, which regulate T-cell activation, can influence active CMV infection in kidney transplant patients. These results should be confirmed by further investigations.