Summary:IL-10 is a potent immunosuppressant which inhibits allo-antigen-specific T cell responses. In addition, IL-10 is a strong endogenous anti-inflammatory cytokine. To investigate the role of IL-10 in the induction of acute GVHD following allogeneic bone marrow transplantation (BMT) we performed a prospective study on spontaneous IL-10 production by peripheral blood mononuclear cells (PBMNC) in 84 patients admitted for allogeneic BMT. High spontaneous IL-10 production by PBMNC at the time of admission and prior to any preparative treatment correlated with a subsequent low incidence of GVHD and transplant-related mortality (8%), as compared to patients with low or intermediate IL-10 production (50%, P Ͻ 0.01). Our data demonstrate the prognostic significance of increased IL-10 production in BMT patients and suggest a major role of IL-10 in maintaining immunobalance in the setting of allogeneic BMT. Bone Marrow Transplantation (2000) 25, 237-241.

No abstract

Intensity of pretransplant conditioning has been closely correlated with regimen related toxicity in patients receiving allogeneic bone marrow transplantation (BMT). In this review, we summarize evidence for a direct link between inflammatory reactions induced by irradiation and cytotoxic treatment and occurrence of acute graft-versus-host disease (GvHD) as well as endothelial complications: In our studies, de novo release of TNFalpha during conditioning was associated with an increased risk of severe GvHD and mortality following BMT, whereas increased spontaneous production of IL-10, an endogenous TNF-antagonist, prior to conditioning protected from these complications. Immunogenetic differences in cytokine regulation and costimulation by endotoxin proved to be important cofactors determining the extent of inflammatory cytokine release in individual patients. Pathophysiological relevance of these findings seems to be confirmed by experimental as well as first clinical trials using TNF-antibodies and related antagonists during pretransplant conditioning. Preclinical experiments suggest additional, cytokine independent inflammatory reactions induced by irradiation such as expression of ICAM-1 and endothelial cell apoptosis. Although the exact impact of these findings on pathophysiology of BMT related complications needs further clarification by future studies, conditioning related inflammation as a first crucial step in induction of GvHD and complications has to be considered when designing new protocols for preparation of patients for allogeneic BMT.

To investigate the role of tumor necrosis factor-α (TNF-α) released by activated macrophages, sequential serum samples of 120 patients undergoing bone marrow transplantation (BMT) were analyzed by enzyme-linked immunosorbent assay. De novo increases in serum TNF-α levels were correlated with the development of acute endothelial complications as well as acute graft-versus-host disease. In addition, the analysis of time courses revealed a different capacity of TNF-α regulation at various phases of BMT. While patients with acute TNF-α release in the first 2 weeks of BMT had a significantly enhanced incidence of complications, a subgroup of 9 patients with chronic asymptomatic release of TNF-α before admission to BMT was observed. These patients were protected from complications in the course of the first 6 months of BMT. Our observations indicate the occurrence of desensitization for TNF-α, as it is also reported after repeated injections of TNF-α or endotoxin in experimental models.

No abstract