High interleukin-10 serum levels are associated with fatal outcome in patients after bone marrow transplantation.

IL-10 plays an important role in the control of immune reactions during systemic infection. Here, IL-10 serum levels were investigated in patients after BMT. The IL-10 levels correlated with the clinical course of the patients and with serum levels of C-reactive protein (CRP) and neopterin (NP). A total of 26 patients with AML (7), ALL (12), CML (2), NHL (3) and multifocal Ewing's sarcoma (2) had received autologous (10) or allogeneic (16) BMT from related (9) or unrelated donors (7). Routine serum samples were obtained prior to BMT and at days 46 and 100 after BMT. However, in patients with severe complications additional samples were drawn at individual points in time. Prior to BMT, IL-10 serum levels were not detectable in 24/24 patients. Post-BMT, 11 patients developed elevated IL-10 levels, of these eight died of complications (DOC), whereas only one of 15 patients with undetectable IL-10 died of complications, indicating that high IL-10 levels were significantly correlated with severe life-threatening complications (chi2, P < 0.01). To determine the pathomechanism and role of the increased IL-10 levels, they were correlated to the respective NP and CRP serum concentrations. CRP and NP concentrations were found significantly elevated in patients with detectable IL-10, indicating a severe acute phase reaction associated with macrophage activation. In conclusion, high IL-10 serum levels in patients after BMT were significantly associated with fatal outcome. Since IL-10 is a strong suppressor of T cell immunity, high IL-10 production in patients with severe complications such as septic shock or GVHD > grade II after BMT might lead to functional immunodeficiency contributing to the poor prognosis of these patients.