Patterns of monocyte subpopulations and their surface expression of HLA-DR during adverse events after hematopoietic stem cell transplantation.

Human leukocyte antigen DR surface expression in "classical" CD14++CD16- (M1), "intermediate" CD14++CD16+ (M2), and "non-classical" CD14+CD16++ (M3) monocytes reflects the activation state of these cells. The full spectrum of monocyte and its function is still unknown. The present pilot study describes the monocyte subpopulations and their human leukocyte antigen DR expression during the post-transplant period as well as during transplant-related adverse events of 30 pediatric patients and young adults with hemato-oncological malignancies and immunodeficiency disorders in comparison to healthy children and young adults. A significant change of the human leukocyte antigen DR expression in all three monocyte subpopulations during the period after bone marrow transplantation depending on the time after transplantation and adverse events could be recognized. Prior to and during sepsis or bacterial infection, a significant decrease in human leukocyte antigen DR expression occurred. A significant increase on CD14++CD16- monocytes could be observed during graft-versus-host disease. The alterations of human leukocyte antigen DR expression on the monocyte subpopulations during adverse events after hematopoietic stem cell transplantation may be a sign of changes in the capacity of these subpopulations. Moreover, human leukocyte antigen DR expression in monocyte subpopulations may be used to monitor treatment responses in these entities.

Impaired suppression of synovial fluid CD4+CD25- T cells from patients with juvenile idiopathic arthritis by CD4+CD25+ Treg cells.

OBJECTIVE: Natural CD4+CD25+FoxP3+ Treg cells play a crucial role in maintaining immune homeostasis and controlling autoimmunity. In patients with juvenile idiopathic arthritis (JIA), inflammation occurs despite the increased total numbers of Treg cells in the synovial fluid (SF) compared to the peripheral blood (PB). This study was undertaken to investigate the phenotype of CD4+ T cells in PB and SF from JIA patients, the function of synovial Treg cells, and the sensitivity of PB and SF CD4+CD25- effector T cells to the immunoregulatory properties of Treg cells, and to study the suppression of cytokine secretion from SF effector T cells by Treg cells. METHODS: The phenotypes of effector T cells and Treg cells of PB and SF from JIA patients and healthy donors were determined by flow cytometry. The functionality of isolated Treg cells and effector T cells was quantified in (3) H-thymidine proliferation assays. Cytokine levels were analyzed using Bio-Plex Pro assay. RESULTS: Compared to PB, SF showed significantly elevated numbers of activated and differentiated CD4+CD45RO+ T cells. Sensitivity of SF effector T cells to the suppressive effects of Treg cells from both PB and SF was impaired, correlating inversely with the expression of CD69 and HLA-DR. However, SF effector T cell cytokine secretion was partly suppressed by SF Treg cells. CONCLUSION: Our findings indicate that regulation is impaired in the SF of patients with JIA, as shown by the resistance of effector T cells to immunoregulation by functional Treg cells. This resistance of the SF effector T cells might be due to their activated phenotype.

Phagocytic activity of monocytes, their subpopulations and granulocytes during post-transplant adverse events after hematopoietic stem cell transplantation.

Phagocytosis of granulocytes and monocytes presents a major mechanism that contributes to the clearance of pathogens and cell debris. We analyzed the phagocytic activity of the peripheral blood cell monocytes, three monocyte subpopulations and granulocytes before and up to one year after hematopoietic stem cell transplantation, as well as during transplant-related adverse events. 25 pediatric patients and young adults (median age of 11.0 years) with hemato-oncological malignancies and non malignancies were enrolled in the prospective study. Ingestion of fluorescence-labeled Escherichia coli bacteria was used to assess the phagocytic activity of monocytes and their subpopulations and granulocytes by means of flow cytometry in the patient group as well as in a control group (n=36). During sepsis, a significant increase of phagocytic activity of monocytes (P=0.0003) and a significant decrease of the phagocytic activity of granulocytes (P=0.0003) and the CD14+ CD16++ monocyte subpopulation (P=0.0020) occurred. At the onset of a veno-occlusive disease, a significant increase of phagocytic activity in the CD14++ CD16+ monocyte subpopulation (P=0.001) and a significant decrease in the phagocytic activity of the CD14++ CD16- monocyte subpopulation (P=0.0048) were observed. In conclusion, the phagocytic activity of monocytes, their subpopulations and granulocytes might be a useful and easy determinable parameter that enables identification of post-transplant complications after hematopoietic stem cell transplantation. The alterations of phagocytic activity contribute to the altered immune response that accompanies adverse events after hematopoietic stem cell transplantation.