Soluble interleukin-2 receptor index predicts the development of acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation from unrelated donors.

Acute graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT) is associated with significant morbidity and mortality. In the present study, we retrospectively evaluated whether soluble interleukin-2 receptor (sIL-2R) index, defined as the ratio of serum sIL-2R levels at neutrophil engraftment to those at the pre-conditioning regimen, was predictive of acute GVHD among 51 patients who underwent allogeneic HSCT as their first transplantation and achieved engraftment. The median sIL-2R index was 3.6, and the sIL-2R values were positively associated with acute GVHD severity (grade 0-I: 3.8 ± 2.0 vs. grade II-IV: 7.1 ± 5.7; P = 0.05). Grade II-IV acute GVHD had a cumulative incidence of 31.4 %, and was significantly more frequent among patients with an sIL-2R index of ≥4.5 (≥4.5: 50.0 % vs. <4.5: 21.2 %; P = 0.03). Multivariate analysis revealed that an sIL-2R index of ≥4.5 [hazard ratio (HR) 3.5, P < 0.01] and donor age of >35 years (HR 3.8, P = 0.02) were significant risk factors for grade II-IV acute GVHD. Therefore, increased sIL-2R levels from baseline to engraftment might predict the risk of moderate-to-severe acute GVHD after allogeneic HSCT from an unrelated donor.