apyrase and Leukemia--Myeloid

Topics: Adenosine Triphosphate; Apyrase; Humans; Leukemia, Myeloid; Programmed Cell Death 1 Receptor; T-Lymphocytes

Natural regulatory T cells (nTregs) ensure the control of self-tolerance and are currently used in clinical trials to alleviate autoimmune diseases and graft-versus-host disease after hematopoietic stem cell transfer. Based on CD39/CD26 markers, blood nTreg analysis revealed the presence of five different cell subsets, each representing a distinct stage of maturation. Ex vivo added microenvironmental factors, including IL-2, TGFβ, and PGE2, direct the conversion from naive precursor to immature memory and finally from immature to mature memory cells, the latest being a no-return stage. Phenotypic and genetic characteristics of the subsets illustrate the structural parental maturation between subsets, which further correlates with the expression of regulatory factors. Regarding nTreg functional plasticity, both maturation stage and microenvironmental cytokines condition nTreg activities, which include blockade of autoreactive immune cells by cell-cell contact, Th17 and IL-10 Tr1-like activities, or activation of TCR-stimulating dendritic cell tolerization. Importantly, blood nTreg CD39/CD26 profile remained constant over a 2-y period in healthy persons but varied from person to person. Preliminary data on patients with autoimmune diseases or acute myelogenous leukemia illustrate the potential use of the nTreg CD39/CD26 profile as a blood biomarker to monitor chronic inflammatory diseases. Finally, we confirmed that naive conventional CD4 T cells, TCR-stimulated under a tolerogenic conditioned medium, could be ex vivo reprogrammed to FOXP3 lineage Tregs, and further found that these cells were exclusively committed to suppressive function under all microenvironmental contexts.

Topics: Apyrase; Autoimmune Diseases; CD4-Positive T-Lymphocytes; Cellular Microenvironment; Cytokines; Dendritic Cells; Dinoprostone; Dipeptidyl Peptidase 4; Forkhead Transcription Factors; Humans; Interleukin-10; Interleukin-2; Leukemia, Myeloid; T-Lymphocytes, Regulatory; Th17 Cells; Transforming Growth Factor beta

Using electron microscope cytochemistry and cells separated on Ficoll-Hypaque, Mg2+-dependent ATPase, ADPase and 5'-nucleotidase were predominantly localized as ectoenzymes on normal human granulocytes. Large deposits of ATPase final reaction product and more finely granular deposits of 5'-nucleotidase final reaction product were firmly attached to the outer surface of cell plasma membranes. The final reaction product from ecto-ADPase was, however, only loosely associated with the plasma membrane. In addition, finer deposits of ADPase final reaction product were seen in specific granules and in background cytoplasm. No nucleotidase phosphatase activity was localized to the alkaline phosphatase-containing granules (phosphasomes) recently described by Rustin et al. In granulocytes from patients with chronic granulocytic leukaemia, ecto-ATPase had a patchy distribution on the plasma membranes. There was considerable heterogeneity between cells with regard to ADPase and 5'-nucleotidase localization. In some cells, ADPase was seen only at both site, while in some cells no activity was detected. 5'-Nucleotidase localization was normal in some cells but lacking from many. No correlation was found between enzyme heterogeneity and the degree of morphological cell maturity.

Topics: 5'-Nucleotidase; Adenosine Triphosphatases; Apyrase; Ca(2+) Mg(2+)-ATPase; Histocytochemistry; Humans; Leukemia, Myeloid; Microscopy, Electron; Neutrophils; Nucleotidases; Phosphoric Monoester Hydrolases; Reference Values

Adenosine diphosphatase (ADPase) activities were studied in human polymorphonuclear leukocytes with a recently developed radio-assay. The neutrophils were homogenized in isotonic sucrose and subjected to analytical subcellular fractionation. The sucrose density gradient fractions were assayed for ADPase activity and for principal organelle marker enzymes. ADPase activity was distributed between the plasma membrane, specific granule and soluble fractions. The plasma membrane and specific granule activities had similar kinetic and inhibitor properties but the cytosolic enzyme was clearly different. Studies with the non-penetrating inhibitor diazotized sulphanilic acid and measurements of latent activity indicate that plasma membrane ADPase activity is located on the external aspect to the cell. Its possible role in inhibiting platelet aggregation is discussed. Neutrophils were isolated from control subjects, patients with chronic granulocytic leukaemia and patients in the third trimester of pregnancy. The specific activities (mU/mg protein) of ADPase activity, in contrast to those of alkaline phosphatase, were similar in all three groups. This result, together with fractionation experiments and inhibition studies strongly suggests that ADPase activity is not attributable to neutrophil alkaline phosphatase.

Topics: Alkaline Phosphatase; Apyrase; Cell Membrane; Centrifugation, Density Gradient; Chemical Phenomena; Chemistry; Cytosol; Female; Humans; Kinetics; Leukemia, Myeloid; Neutrophils; Phosphoric Monoester Hydrolases; Pregnancy; Subcellular Fractions