Serum interleukin-6 levels during bone marrow transplantation: impact on transplant-related toxicity and engraftment.

The biological properties of IL-6 include the induction of acute phase proteins, stimulation of hematopoietic stem cell growth and thrombopoiesis. Serum levels of IL-6 were closely monitored in 66 patients before and after allogeneic (n = 37), autologous bone marrow transplantation (n = 8) or autologous peripheral blood stem cell transplantation (n = 21). Almost every patient showed elevated IL-6 serum levels during the aplastic phase. Patients then suffered from mucositis, had elevated C-reactive protein (CRP) and usually body temperatures of above 38 degrees C. It was investigated whether IL-6 serum levels, apart from inducing acute phase reactions, correlated with transplant-related complications or leukocyte and thrombocyte engraftment. By statistical analysis, a correlation was found between IL-6 and CRP and between IL-6 and fever. In contrast, no correlation was found between IL-6 and elevated serum bilirubin as a marker for hepatotoxicity. IL-6 showed a weak negative correlation with leukocyte or platelet counts. In contrast, the day of platelet engraftment correlated with the day of peak serum IL-6 value, possibly indicating an influence of IL-6 on platelet engraftment.

Serum levels of stem cell factor in patients during transplantation of bone marrow or peripheral blood stem cells.

Stem cell factor (SCF) synergizes with other cytokines in vitro to stimulate the proliferation and differentiation of cells of the myeloid, megakaryocytic, erythroid, and lymphoid lineages. In vivo, it may play a role in engraftment after transplantation of bone marrow (BM) or peripheral blood stem cells (PBSC). Serum levels of SCF were closely monitored in 82 patients before and after allogeneic (n = 38), autologous (n = 6), or syngeneic (n = 1) BM transplantation (BMT) or autologous PBSC transplantation (PBSCT) (n = 37), respectively. SCF serum levels fluctuated around a mean in patients after allogeneic or autologous BMT or after PBSCT. In two patient subgroups (5 patients with acute myeloid leukemia [AML] and 6 patients with chronic myelogenous leukemia [CML]) with identical pretransplant conditioning regimen followed by allogeneic BMT, serum IL-6 levels significantly increased up to day +14 (p < 0.05). Correlation was not found between SCF serum levels and leukocyte or thrombocyte counts or the day of engraftment of these cell types. These data are a basis for further studies and constitute a further mosaic stone in understanding the changes in the complex cytokine network during engraftment.