HAEMOPOIESIS

Mohammed Basil.p.a. Second Year BSc MLT

Archana madam & Rijo jeckeb joseph sir (Pathology dept.)

Erythropoiesis or haemopoiesis is the physiological process of production of RBC. It is mostly place in the bone marrow but it depend upon the stage of life.

 Life stages  Granulocytes  Erythrocytes  Platelets  Lymphocytes  Derived from Stem cells .01% -.05% of the marrow cells

 Stem cells  Self renewal  Plasticity  Progenitor cells  Developmentally-restricted cells  Mature cells  Mature cell production takes place from the more developmentally-restricted progenitors

 Yolk sac (1-3 month) (1-3 month)  Liver and spleen (3-6 month) (3-6 month)  Bone marrow (After birth) (After birth)

 Self-renewal  Normally in G 0 phase of cell cycle  The capacity for self-reproduction is vastly in excess of that required to maintain cell production for normal lifetime  As cells increase in number they differentiate as well  Multipotentiality  Capacity to generate cells of all the lymphohaemopoietic lineages

 Encompasses from immediate progeny of stem cells to cells committed to one differentiation lineage  Progenitor cells become progressively more restricted in their differentiation and proliferation capacity  Late progenitor cells eventually restricted to one lineage

 There should be a balance between cell production and cell death except at the times of requirement Controlled cell death Controlled cell production

 GM-CSF  Granulocyte-Macrophage colony stimulating factor  M-CSF  Macrophage colony stimulating factor  Erythropoietin  Erythropoiesis stimulating hormone (These factors have the capacity to stimulate the proliferation of their target progenitor cells when used as a sole source of stimulation)  Thrombopoietin  Stimulates megakaryopoiesis

 Cytokines  IL 1 (Interleukin 1)  IL 3  IL 4  IL 5  IL 6  IL 9  IL 11  TGF-β  SCF (Stem cell factor, also known as kit-ligand) Cytokines have no (e.g IL-1) or little (SCF) capacity to stimulate cell proliferation on their own, but are able to synergise with other cytokines to recruit nine cells into proliferation

Local environmental control Stromal cell mediated Haemopoiesis Haemopoietic growth factors (Humoral regulation) Apoptosis

 Regulated physiological cell death  Homeostasis  Morphological evidence  Enzymatic digestion of DNA and cell disintegration  Caspases  Endonuclease  Two major pathway of activation of caspases  Membrane signalling  Cytochrome c release

 Lifespan – 120 days  Non nucleated  Biconcave disc  Production regulated by Epo  Needs Fe, B12, folate & other elements for development

 Granulocytes  Neutrophils  Eosinophils  Basophils  Only mature cells are present in peripheral blood E N B

 Neutrophil  2-5 lobe nucleus  Primary or secondary granules  Pink (azurophilic granules)  Grey-blue granules  Life 10 hours

 Eosinophils  Coarser & more deeply red staining granules  Rarely more than two lobes of nucleus  Special role in allergy, inflamation & parasite infection  Basophils  Occasionally seen  Dark cytoplasmic granules  Role in hypersensitivity response  Give rise to mast cells

 Larger than lymphocyte  Oval or indented nucleus  Monocytes >>>>to macrophage  Specific function depends on the tissue type

 Immunologically competent cells  Primary lymphoid organs  Bone marrow  Thymus  Secondary lymphoid organs  Lymph nodes  Spleen  Lymphoid tissues  Lymphocytes  B and T lymphocytes  NK killer cells

 Platelet play a major role in primary hemostasis  Life span 7-10 days  Production, fragmentation of cytoplasm  Megakaryocytes undergoes endomitotic division  1/3 in spleen

 Normal haemopoiesis is necessary for the survival  It is under the control of multiple factors  Normal bone marrow environment is necessary for normal haemopoiesis  Decreased production results in cytopenias