title: Functional polymorphism of CTLA-4 and ICOS genes in allogeneic hematopoietic stem cell transplantation.
abstract: BACKGROUND
  T cells play a critical role in alloimmune recognition and thus contribute to graft-versus-host disease (GVHD) and relapse prevention in hematopoietic stem cell transplantation (HSCT). Cytotoxic T lymphocyte antigen-4 (CTLA-4) and inducible costimulator (ICOS) are costimulatory molecules of T cell activation and their genetic variations can affect the capacity of T cells to become activated or inactivated.
  
  
  METHODS
  We examined CTLA-4 (-318 C/T and +49 A/G) and ICOS (c.602 A/C and c.1624 C/T) genotypes in 123 patients with HSCT and their HLA-matched sibling donors, and then evaluated the impacts of the genetic polymorphisms on GVHD, disease relapse, and survival.
  
  
  RESULTS
  By multivariate analysis, the donor CTLA-4 -318 TT genotype increased the risk of disease relapse (Hazard ratio [HR]: 5.91, 95% confidence interval [CI]: 1.17-29.79, P=0.0313). Recipients who received a graft from a donor with ICOS c.602 CC genotype had worse disease-free survival (HR: 5.97, 95% CI: 1.49-23.87, P=0.0115). Additionally, recipients with ICOS c.1624 TT genotype had worse overall survival (HR: 12.98, 95% CI: 2.58-65.35, P=0.0019). Nevertheless, CTLA-4 and ICOS genotypes were not associated with acute and chronic GVHD.
  
  
  CONCLUSIONS
  Both donor and recipient CTLA-4 and ICOS gene polymorphisms might be of importance for the outcome of allogeneic HSCT.
authors.affiliation: Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Jui
authors.initials: J
authors.lastname: Wu
authors.forename: Jih-Luh
authors.initials: JL
authors.lastname: Tang
authors.forename: Shang-Ju
authors.initials: SJ
authors.lastname: Wu
authors.forename: Hoi-Yan
authors.initials: HY
authors.lastname: Lio
authors.forename: Ya-Chien
authors.initials: YC
authors.lastname: Yang