Effect of donor CTLA-4 alleles and haplotypes on graft-versus-host disease occurrence in Tunisian patients receiving a human leukocyte antigen-identical sibling hematopoietic stem cell transplant.

The CTLA-4 genetic variation, such as single nucleotide polymorphisms (SNPs) may be critical and can affect the functional activity of cells that initiate the graft-versus-host disease (GVHD) effects. The aim of this study is to examine the effect of donor CTLA-4 alleles and haplotypes for the -318C>T and the 49A>G polymorphisms on the occurrence of GVHD in Tunisians recipients of HSCs. A total of 112 patients and their 112 respective sibling donors of HSCs were enrolled in this study. All patients had either grades 0-I or grades II-IV acute GVHD, or chronic GVHD. The SNPs genotyping assay was performed using sets of sequence specific primers (SSP-PCR). The single marker association analysis showed that the 49G allele, in a genetic recessive model, may be a potential risk factor only for the chronic GVHD (p = 0.032, odds ratio [OR] = 2.58, 95% confidence interval = 1.05-6.32). The haplotypes analyses showed that the CTLA-4 -318C49G nucleotide combination is significantly associated with the incidence of chronic GVHD (p = 0.043, χ² = 3.27). Donor CTLA-4 -318C49G haplotype may be a significant risk factor for developing chronic GVHD after allo-stem cell transplantation. We suppose that donor T cells expressing this haplotype in a homozygous state have higher proliferation than those expressing other haplotypes, especially after recognition of the recipient's minor histocompatibility antigens.