Haemopoiesis Clinical application Dr. Tariq M. Roshan Department of Hematology PPSP

Introduction Life span Granulocytes Erythrocytes Platelets Lymphocytes

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

Cell hierarchy (Haemopoiesis schematic representation)

Sites of Haemopoiesis Yolk sac Liver and spleen Bone marrow Gradual replacement of active (red) marrow by inactive (fatty) tissue Expansion can occur during increased need for cell production

Stem cells 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

Progenitor cells 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

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

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

Interaction of stromal cells, growth factors and haemopoietic cells

Local and Humoral regulation of Haemopoiesis

Haemopoietic growth factors 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

Haemopoietic growth factors 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

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

Functions of erythrocytes Transport of respiratory gases Large surface area : volume ratio Flexible biconcave disc Haemoglobin for exchange of gases Capable of glycolysis for the source of energy for cell survival

Erythrocyte disorders Qualitative Haemoglobin defect (Anemia, Thalassaemia, sickle cell anemia etc) Membrane & enzyme abnormalities (G6PD, eliptocytosis, stomato-ovalocytosis) Quantitative Increased (polycythemia) inherited / acquired Decrease (inherited / acquired hypoplasia) Bleeding

Anaemia Reduction in circulation haemoglobin Nutritional deficiency anaemias Iron deficiency B12 & folate deficiency anaemia Protein deficiency anaemia Scurvy & other element deficiency Iron deficiency anaemia B12 & folate deficiency

Nutritional deficiency anaemia clinical application Angular Cheilosis Koilonychia Glossitis Marrow iron stores Plummer-Vinson syndrome

Anaemia; Globin chain defects Thalassaemias Reduced globin chain synthesis Alpha and Beta chain synthesis defects Haemoglobinopathies Abnormal globin chain synthesis Sickle cell disease Thalassaemia

Anaemia; Globin chain defects X-ray appearance of Thalassaemic patient Hemoglobin electrophoresis for the diagnosis of thalassaemia

Anaemia; Membrane and enzyme defects Membrane defects Elliptocytosis  Hemolysis Stomato-ovalocytosis  Without haemolysis Red cell enzymopathies G6PD  Hemolysis after oxidant stress Blood loss Elliptocytosis G6PD deficiency

Anaemia; Reduced bone marrow erythroid Marrow failure Marrow infiltration Trephine biopsy (Aplastic Anemia) Marrow infiltration Normal trephine

Leucocytes Lymphocytes Monocytes / Macrophages Granulocytes Neutrophils Eosinophils Basophils N E B L M Band P

Lymphocytes Count varies with age 1.5 – 3.5 x10 9 /l The subset cells are B-cells Antibody mediated immunity T-cells Cell mediated immunity NK cells

Disorders of lymphocytes Benign disorders Lymphocytosis Viral infections Bacterial infections Protozoal infections Lymphopenia Marrow failure (drugs, irradiation) Infections (viral infections) Immune-deficiency syndromes Antibody deficiency Cell mediated immune defiency Combined cell and antibody immune deficiency

Disorders of lymphocytes Benign disorders Infectious mononucleosis Epstein-Barr virus infection Autoimmune lymphoproliferative syndrome

Disorders of Lymphocytes Malignant disorders Acute lymphoblastic leukemia (ALL) Chronic lymphocytic leukemia (CLL) Lymphomas Non Hodgkin’s lymphoma Hodgkin’s disease ALL CLL

Monocytes Count is x 10 9 /l Functions Antigen presentation Cytokine production Phagocytosis

Disorders of Monocytes Monocytosis Benign Chronic bacterial infection Malignant Chronic Myelomonocytic Leukaemia CMML

Neutrophils Count x 10 9 /l Granular cytoplasm Transient stay in blood Major phagocytic role Bacterial killing 3-5 lobes of nucleus

Disorders of Neutrophil Neutrophilia Infection (Bacterial) Inflammatory conditions Neoplasia Metabolic conditions  Uraemia Haemorhage / haemolysis Corticosteroids Marrow infiltration CML MM M N Baso

Disorders of Neutrophil Neutropenia Count < 1.5 x 10 9 /l Drugs Chemotherapy Viral infection Inherited disorders Morphological abnormalities Pelger-Huet anomaly May-Hegglin anomaly Chediak-Higashi syndrome

Myeloid malignancies Acute Myeloid Leukaemia Chronic Myeloid Leukaemia Myeloproliferative disorder Acute Myeloid Leukaemia (AML M-3) Chronic Myeloid Leukaemia

Eosinophils Count 0.2 – 0.8 x 10 9 /l Bilobed nucleus Phagocytic activity is low Modulation of hypersensitivity and allergic reactions

Disorders of Eosinophil Eosinophilia >0.8 x 10 9 /l Allergic reactions Parasitic infections Malignancy HD, NHL Inflammatory conditions Myeloproliferative disorders Hypereosinophilic syndrome

Basophils Count 0.1 – 0.2 x 10 9 /l Bilobed nucleus Nucleus is hided behind the granules Inflammatory response Basophilia is seen in Myeloproliferative disorders (CML)

Platelets Platelets are fragments of cytoplasm of bone marrow megakaryocytes Count 150 – 400 x 10 9 /l Major role in coagulation

Summary As other rapidly regenerating tissues, the haemopoietic system is organized in hierarchical manner Better understanding of the factors controlling haemopoiesis is leading a way to better patient care and reconstitution of different lineages, which has been refractory to stimulation efforts previously Understanding of stem cell physiology & pathology will be essential in the coming years for a hematopathologist

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