Role of interleukin-6 polymorphism in acute graft-versus-host disease risk prediction in allogeneic hematopoietic stem cell transplantation

BACKGROUND: This study aimed to determine the association of single-nucleotide polymorphisms (SNPs) of interleukin-6 (IL-6) gene with the survival and disease status of patients after allogeneic hematopoietic stem cell transplantation. MATERIALS AND METHODS: It was a prospective cohort study of total 102 participants, 51 patients along with their donors who had human leukocyte antigen-identical-matched allogeneic hematopoietic stem cell transplantation (aHSCT). Their pretransplant and posttransplant blood samples were collected for extraction of DNA for genotyping by sequence-specific primers polymerase chain reaction and gel electrophoresis followed by sequencing. The pre- and posttransplant levels of IL-6 were measured using enzyme-linked immunosorbent assay technique. RESULTS: The mean age of our patients was 19.83 ± 12.5 years having males 65 (63.7%) and females 37 (36.3%). The frequency of −174G/C SNP among acute graft-versus-host disease (aGVHD) group was GG = 53.8%, GC = 34.6%, and CC = 11.5%, and for −597G/A SNP, it was GG = 69.2%, GA = 15.4%, and AA = 15.4%. Our results showed that the presence of G allele in both homozygous and heterozygous forms was associated with increased aGVHD incidence, while the homozygous CC and AA mutant genotypes correlated with the lowest number of cases of aGVHD. The polymorphism −597G/A was significantly associated with the incidence of aGVHD with P = 0.04. The GG genotype in −174G/C and −597G/A was found to be significantly associated with aGVHD with P < 0.0001. High serum levels of IL-6 pre- and posttransplant were found to be significantly associated with the incidence of aGVHD with P < 0.0001. CONCLUSION: We concluded that the two SNPs − 174G/C and − 597G/A in the promoter region of IL-6 gene present either in donors or recipients predisposed to increase the risk of development of aGVHD following aHSCT. Their evaluation in our transplant setting may help in the risk stratification of transplant recipients early in time and predict the onset of aGVHD and mortality.