The influence of infection early after allogeneic stem cell transplantation on the risk of leukemic relapse and graft-versus-host disease

An infection after allogeneic stem cell transplantation (SCT) can affect the activity of immune cells; and increase the level of proinflammatory cytokines. Further, a post-SCT infection may influence the milieu of the graft-versus-leukemia (GVL) effect and graft-versus-host disease (GVHD). We performed a retrospective study of patients with acute leukemia who had undergone allogeneic SCT using the same preparative regimens and bone marrow as the stem cell source to determine if early post-transplant infection was associated with the risk of leukemic relapse and GVHD. The analysis revealed that patients who had a febrile infection (FI) before post-transplant day 21 (FI group) had a lower actuarial probability of leukemic relapse (P < 0.001) and a higher relapse-free survival rate (P = 0.012) than those patients who did not have a FI before post-transplant day 21 (non-FI group). The experience of early post-transplant FI (HR = 0.316; 95% CI = 0.174-0.575; P < 0.001), together with the presence of chronic GVHD and high risk cytogenetics, were independent predictive factors for post-transplant leukemic relapse. The FI group had a trend towards a higher lymphocyte count on post-transplant day 21 than the non-FI group (P = 0.063), despite the delayed recovery of the platelet count and a trend towards delayed recovery of the neutrophil count. These findings suggest that a change in the immunologic network by infectious diseases in the early post-transplant period favors the milieu of the GVL effect. The specific immunologic change during FI, which can potentiate the GVL effect, remains to be determined.