IL15 and acute graft versus host disease: Finally, in a multivariate Cox model, neither median IL-7 levels (P = 0.17 with a trend for an inverse correlation) on days 7–14 nor median IL-15 levels (P = 0.21 with a trend for a positive correlation) on days 7–14 correlated with occurrence of grade II–IV acute GVHD the first 200 days after transplantation.