High Levels of B Cell Activating Factor During the Peritransplantation Period Are Associated with a Reduced Incidence of Acute Graft-versus-Host Disease following Myeloablative Allogeneic Stem Cell Transplantation

B cell activating factor (BAFF), also known as B cell survival and activation factor, is associated with autoimmune disease and chronic graft-versus-host disease (cGVHD). T cells are known to be modulated by soluble BAFF (sBAFF). Considering the possible association of sBAFF with T cell as well as B cell function, sBAFF during the peritransplantation period may affect the development of acute GVHD (aGVHD). To test this hypothesis, we evaluated 45 patients who had undergone myeloablative (MA) allogeneic stem cell transplantation (SCT) for hematologic malignancy. Serum sBAFF levels were measured before conditioning and on day 0, day +7, and day +14. Thirty-three of the 45 patients (cumulative incidence, 73%) developed aGVHD between 16 days and 98 days posttransplantation. Repeated-measures analysis of variance revealed significantly lower sBAFF levels during the peritransplantation period in patients with aGVHD than in those without aGVHD (P = .001). Receiver operating characteristic curve analysis revealed that sBAFF levels at every time point were available for the prediction of aGVHD development, and that patients with a sBAFF level >43 pg/mL at each time point (which could ensure 75% sensitivity and 73%-82% specificity for the prediction of aGVHD at every time point) had a significantly lower cumulative incidence of aGVHD. This study is the first to demonstrate that sBAFF level during the peritransplantation period not only may be predictive of aGVHD, but also may have a protective effect against aGVHD in humans. Further investigation is needed to confirm our findings.