Effect of IL-2 polymorphism rs2069762 on single-unit cord blood transplant outcomes

Interleukin-2 (IL-2) is one of the most important cytokines that regulate the activation and proliferation of T cells and natural killer cells. The production of IL-2 may be affected by polymorphisms in the promoter region of the IL-2 gene (rs2069762). In allogeneic hematopoietic cell transplantation (HCT) from adult donors, rs2069762 has been associated with the incidence of acute and chronic graft-versus-host disease (GVHD). However, the impacts of IL-2 polymorphism on cord blood transplantation (CBT) outcomes remain unclear.

The objective of this study was to assess the impact of IL-2 polymorphism rs2069762 on transplant outcomes, such as hematopoietic recovery, GVHD, overall survival, relapse, and non-relapse mortality (NRM) after CBT.

We conducted a retrospective analysis of data from adult patients who underwent single-unit CBT at our institution from November 2005 to March 2023 for whom DNA samples from recipients and donors were available. IL-2 genotyping was performed using real-time polymerase chain reaction with the TaqMan® SNP genotyping assay for rs2069762.

A total of 143 recipient and donor pairs were included in this study. The proportion of recipient IL-2 polymorphism rs2069762 was 48 % (n = 69) for AA, 42 % (n = 60) for CA, and 10 % (n = 14) for CC. The proportion of donor IL-2 polymorphism rs2069762 was 43 % (n = 61) for AA, 48 % (n = 69) for CA, and 9 % (n = 13) for CC. In the multivariate analysis, the use of an rs2069762 CA + CC donor was associated with lower neutrophil recovery compared to an rs2069762 AA donor (hazard ratio [HR], 0.66; 95 % confidence interval [CI], 0.50-0.88; P = 0.004). Furthermore, recipients of rs2069762 CA + CC were associated with higher NRM compared to recipients of rs2069762 AA (HR, 2.32; 95 % CI, 1.01-5.34; P = 0.047). Serum IL-2 levels at 8 weeks were significantly higher in rs2069762 CA + CC recipients compared to those with rs2069762 AA recipients (P = 0.014).

Our data showed that donor IL-2 polymorphism affects neutrophil recovery and recipient IL-2 polymorphism affects NRM in adults undergoing single-unit CBT. The polymorphism of IL-2 rs2069762 in recipients and donors might be associated with the clinical outcomes of single-unit CBT.