Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The current hypothesis for the pathogenesis of myelofibrosis involves the intramedullary release of growth factors from defective or abnormal megakaryocytes. We describe a case of an acute micromegakaryocytic leukaemia, in a patient with chronic myelofibrosis, that provides additional evidence for this concept. The micromegakaryocytes, which reached 223 x 10(9)/l, were characterized morphologically by both light and electron microscopy, immunocytochemically and by platelet peroxidase activity. The cells were shown to have a mature cytoplasm, containing alpha granules and the associated proteins; vWF:Ag, fibrinogen, fibronectin and protein S. DNA analysis, by both a Seescan Solitaire Plus image analysis system and flow cytometry, revealed nuclear immaturity, with 92% of cells being diploid. Serum markers of connective tissue synthesis, namely carboxy terminal peptide of procollagen I (PICP), procollagen terminal peptide III (PIIIP) and laminin all increased significantly following transformation and were associated with an increase in platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta). These observations support the current hypothesis for bone marrow fibrosis formation and provide, for the first time, a link between in vivo growth factor release, bone marrow stromal turnover and megakaryocyte mass. In addition, the release of biologically active TGF-beta may explain both the increased fibronectin and angiogenesis characteristic of myelofibrotic bone marrow.
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PMID:Characterization of an acute micromegakaryocytic leukaemia: evidence for the pathogenesis of myelofibrosis. 843 38

Endoglin (CD105) is a component of the transforming growth factor-beta (TGF-beta) receptor (TGF-betaR) complex. Together with betaglycan, CD105 is considered as a TGF-betaR accessory molecule (also called TGF-betaRIII), but its functions in the receptor-ligand interactions are still poorly understood. A small subset of human CD34+ hematopoietic stem/progenitor cells that has phenotypic and functional features suggestive of very primitive hematopoietic cells expresses the CD105 antigen. CD34+/CD105+ cells recirculate in the peripheral blood of mobilized subjects and can be purified by immunomagnetic isolation strategies. The hematopoietic potential of these CD34+/CD105+ cells appears to be sustained by a combination of hematopoietic and non-hematopoietic cytokines, which comprises Flt3 ligand, erythropoietin, interleukin-15 and vascular endothelial growth factor. Endogenous TGF-beta1 is a crucial factor for the maintenance of CD34+/CD105+ immaturity acting through positive modulation of both CD105 and CD34 molecules in the absence of relevant effects on the cell cycle profile. CD105 is absent on very primitive CD34-/lineage-/CD45+ (CD34-Lin-) human hematopoietic cells isolated from cord blood. However, in vitro exposure of CD34-Lin- cells to exogenous TGF-beta1 causes the appearance of a discrete population of CD34+/CD105+ cells. Collectively, available data on CD105 expression and function in primitive hematopoiesis indicate that this molecule could cooperate with the dissociation of TGF-beta1 cell cycle effects from its other effects on cell survival and differentiation.
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PMID:CD105 (endoglin) expression on hematopoietic stem/progenitor cells. 1191

There is good clinical and experimental evidence that oral tolerance exists in man and that the timing of antigen (food) administration is an important factor in the development of food allergic sensitisation and disease. Induction of tolerance is often seen as a T-helper 2-skewed response, which on one side may prevent harmful mucosal immune reactions, but on the other side may contribute to adverse responses in the susceptible individual. The primary mechanisms by which tolerance may be mediated include T-cell deletion, anergy, suppression 'ignorance' and apoptosis. Cell-mediated delayed hypersensitivity reactions (T-helper 1), which are implicated as a pathogenetic principle in the development of autoimmune and gastrointestinal inflammation are particularly well suppressed. Regulatory events during the induction of tolerance (or sensitisation) are not well characterised and remain at times controversial. The balance between tolerance (suppression) and sensitisation (priming) is dependent on several factors, such as: (a) genetic background; (b) nature of antigen and dose of antigen; (c) frequency of administration; (d) age (maturity v. immaturity) at first antigen exposure; (e) immunological status of the host (e.g. virus infection); dietary exposure of the mother; (g) antigen transmission via breast milk, and others. Overall, there is evidence in rodents that multiple low-dose feeds are more likely to induce regulatory cytokines (e.g. transforming growth factor-beta, interleukins 10 and 4) in part secreted by CD4+CD25+ T-regulatory cells. Despite the powerful suppressive effect of oral antigen exposure observed in experimental models, its application in clinical trials of autoimmune diseases has not yet yielded the expected beneficial results.
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PMID:Immunity induced after a feed of antigen during early life: oral tolerance v. sensitisation. 1206 95

The diverse clinical presentations of cutaneous T cell lymphoma (CTCL) have been unified by immunologic characterization of the malignant T cells as an expansion of clonal, CD4+ inducer T cells with affinity for epidermal association with Langerhans cells (LC), an immature member of the dendritic cell (DC) family. Features of the life cycle of CTCL have recently been elucidated through development of an in vitro cell culture system. In this system, the proliferation and survival of the CTCL cells is tied to an association with immature monocyte-derived DC. Growth of the CTCL cells requires direct contact with the DC and both cell types survive in the presence of supportive cytokines for 3 months. Separation of the CTCL cells and the DC, or DC maturation truncates the synergy between the two cell populations and results in rapid death of both cell types. The CTCL cells perpetuate DC immaturity and survival through secretion of interleukin 10 (IL10) and transforming growth factor-beta (TGF-beta). The immature DC are aggressively phagocytic and can engulf apoptotic CTCL cells that have exhausted their proliferative potential and present peptides derived from the apoptotic material in class II MHC molecules to the T cell receptor (TCR) of the CD4+ CTCL cell. CTCL cells are induced to become T-regulatory (Treg) cells when their TCR is triggered by DC class II presentation of peptides derived from apoptotic material. Treg CTCL cells suppress immune responses and secrete IL10 and TGF-beta, cytokines that perpetuate DC immaturity, providing continued opportunity for DC stimulation of CTCL cell growth. Understanding the CTCL cell life cycle unveils a variety of potential targets that can be exploited for therapeutic intervention.
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PMID:The life cycle of cutaneous T cell lymphoma reveals opportunities for targeted drug therapy. 1557 18