Hematology And Immunology Lecture Notes PDF

Hematology and Immunology Eric Hanson PHAR 413 (Day 1) Erythrocyte Leukocyte Platelet 1 Learning Outcomes Blood Components  List the components of plasma.  Describe the role of plas...

Hematology and Immunology Eric Hanson PHAR 413 (Day 1) Erythrocyte Leukocyte Platelet 1 Learning Outcomes Blood Components  List the components of plasma.  Describe the role of plasma proteins in capillary exchange.  Describe the role and significance plasma proteins can play in drug binding.  Identify red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes) as cellular components of blood.  Summarize the basic functions of erythrocytes, leukocytes, and platelets. Hematopoiesis  Describe the process of hematopoiesis.  Identify pharmacologic agents that stimulate leukocyte, platelet, and erythrocyte production. 2 Learning Outcomes Erythropoiesis  Describe the process of erythropoiesis in terms of: major sites responsible for erythropoietin and erythrocyte production. proteins/enzymes involved in the regulation of erythropoietin production, and their regulation by hypoxia. function of erythropoietin. conditions that stimulate or inhibit erythrocyte production.  Identify therapeutic agents that stimulate erythrocyte production.  Describe the causes and types of the major forms of anemia.  Identify the significance of routine hematology laboratory tests including complete blood count (CBC) and mean corpuscular volume (MCV)  Identify the role of vitamin B12 and folic acid in the maturation of red blood cells. 3 Learning Outcomes Erythropoiesis (cont.)  Identify the characteristics of a reticulocyte, and normal reticulocyte count.  Identify the causes of an abnormal reticulocyte count. Polycythemia  Identify the defining characteristics of polycythemia vera and secondary polycythemia. Blood types  Describe the different red blood types and red blood cell compatibility for safe blood transfusion. 4 Resources  Access Pharmacy:  Harper's Illustrated Biochemistry, 32e  Chapter 53 (section X)  Harrison's Principles of Internal Medicine, 21e  Chapter 63 in (part 2)  Chapters 97 – 100 (part 4)  Pharmacotherapy: A Pathophysiologic Approach, 11e  Chapter 118 (section 17) 5 Blood  Primary transport system of the body  O2 from lungs to tissues  Nutrients (e.g. glucose, fatty acids, amino acids)  Removal of waste (e.g. CO2 and urea)  White blood cells to sites of infection  Vitamins  Hormones  Clotting carried out by plasma proteins and platelets  Regulation of water balance  Regulation of body temperature 6 Blood components  Blood volume is ~7% of body weight (~5 - 6 L male, ~4 - 5 L female)  Blood is divided into  Plasma  Hematopoietic cells  Red blood cells (erythrocytes), *~5 x 106/ml Hematocrit is the percent of red blood cells in whole blood Circulate for 120 days  White blood cells (leukocytes), *4,500 - 10,000/ml  Platelets, *150,000 - 400,000/ml *values represent whole blood; 1,000,000 ml in 1 liter 7 Plasma proteins  Synthesized in liver (except for g globulins)  Total protein concentration = 5.9 - 8.0 g/dL  a1-globulin  a2-globulin Transport of lipids, iron, fat-soluble vitamins, hormones, and other molecules  b-globulin Immunoglobulins (antibodies) produced by lymphocytes and  g-globulin function in immunity (IgG, IgA, IgM, IgD, and IgE)  Albumin (~70% Transport of free fatty acids, steroid hormones, bilirubin of total plasma and other molecules; contributes 75 - 80% of total osmotic pressure of blood; albumin (and other plasma protein) proteins) can bind certain drugs 8 Blood components Plasma Hematopoietic cells 9 Plasma proteins and fluid distribution between blood and tissues  Capillary exchange maintains blood volume and pressure  Plasma proteins contribute to colloid osmotic pressure (oncotic pressure), with albumin being the most significant  Colloid osmotic pressure pulls water from tissues into plasma (oncotic pressure)  Hydrostatic pressure forces fluid out the capillary 10 Plasma proteins and fluid distribution between blood and tissues 11 Hematopoietic cells  Platelets (thrombocytes)  White blood cells, WBCs (leukocytes)  Three types of granulocytes: neutrophils, eosinophils, and basophils (innate branch)  Two types of agranulocytes: lymphocytes and monocytes (adaptive/acquired branch)  Red blood cells, RBCs (erythrocytes)  Circulate for 120 days  200 billion produced in 24 h (represents ~1% of all RBCs) 12 Hematopoiesis  Blood cell formation  Cells that make up blood are constantly being produced in bone marrow  Myeloid and lymphoid cell lineages are derived from multipotent hematopoietic stem cells 13 Hematopoiesis  Hematopoietic growth factors are proteins that stimulate hematopoietic stem cells to proliferate, differentiate, and mature into any blood cell type  Hematopoietic differentiation is hierarchical  Less specialized cell    More specialized cell  Number of different paths a developing blood cell can take becomes progressively more restricted 14 Hematopoiesis Multipotent hematopoietic stem cell Terminally differentiated cell 15 Hematopoiesis  Hematopoiesis takes place in the bone marrow (e.g. sternum, and pelvis) 16  Circulation Bone Marrow Hematopoiesis 17 Hematopoietic growth factors  Growth factors bind to receptors and stimulate the growth and differentiation of specific lineages  Erythropoietin (EPO)  erythrocyte production (erythropoiesis)  Thrombopoietin (TPO)  plate production (thrombopoiesis)  G-CSF (granulocyte colony-stimulating factor)  neutrophil production 18 red boxes = examples of growth factors used as therapeutic agents 19 Drugs that stimulate leukocyte production  Neutropenia (low neutrophil count)  Decreased production in bone marrow (myelosuppression)  Chemotherapy  Aplastic anemia (rare, also decreases other leukocytes, platelets, and erythrocytes)  Blood cancers  Radiation  B12 or folate deficiency  Increased destruction (autoimmune neutropenia)  Drugs that stimulate leukocyte production  Recombinant human G-CSF (filgrastim/Neupogen)  Long-acting pegylated recombinant human G-CSF (PEGfilgrastim/Neulasta)  Covalent attachment of polyethylene glycol (PEG)  Recombinant human GM-CSF (sargramostim/Leukine) 20 Drugs that stimulate platelet production  Thrombocytopenia (low platelet count) with increased risk of bleeding  Decreased platelet production  Sequestration in spleen  Increased platelet destruction  Drugs that stimulate platelet production  Oprelvekin (Neumega)  Recombinant human IL-11 (rhIL-11)  Approved for chemotherapy-induced thrombocytopenia  Romiplostim (Nplate)  Peptide fusion protein (TPO receptor agonist)  Approved for ITP (idiopathic/immune thrombocytopenic purpura)  Eltrombopag (Promacta)  Small molecule (TPO receptor agonist)  Approved for ITP 21 Erythrocytes (RBCs)  Carry O2 to tissues  ~270,000,000 hemoglobin molecules/erythrocyte  120 day lifespan (200 billion day destroyed by the spleen and liver)  Most numerous cells in the blood at ~5.2 × 106/ml (men); 4.6 × 106/ml (women)  Biconcave shape increases surface-to-volume ratio facilitating gas exchange  No organelles (e.g. nucleus, mitochondria) 22 Erythrocytes and erythropoiesis  Erythrocytes circulate ~120 days  Erythrocytes are the most common blood cell type, 5 x 106/ml  Number of circulating erythrocytes remains constant and reflects a balance between production (~200 x 109/day) and destruction (~200 x 109/day)  Erythrocytes produced in bone marrow and destroyed in spleen and liver  O2 carrying capacity of blood measured as  Hb  Hematocrit (packed RBCs) 23 Erythropoiesis  Process of erythrocyte production is 3 – 5 days  Begins when multipotent stem cells undergo a series of differentiations  Developing erythrocyte continues to become smaller eventually entering the circulation as a reticulocyte  Reticulocytes released from the bone marrow circulate for 1 - 2 days before becoming mature erythrocytes  Reticulocytes retain ribosomes and mRNA and are capable of synthesizing Hb  Reticulocytes loose ribosomes as they become mature erythrocytes  Mature erythrocytes do not contain organelles 24 Erythropoiesis  Erythropoiesis requires vitamin B12 and folic acid for DNA synthesis B12 and/or folic acid deficiency can lead to megaloblastic anemia  Erythropoiesis requires iron for hemoglobin synthesis  ~2 million erythrocytes produced every second (>200 billion/day) to replace cells lost through normal turnover 25 Erythropoietin (EPO)  Lineage-specific growth factor that stimulates the multiplication and maturation of erythroid progenitors  Protein hormone produced primarily by the kidney  Synthesis regulated by O2 26 Hypoxia-induced erythropoiesis Im ba l an ce Normal blood O2 levels Stimulus: Hypoxia due to  decreased RBCs  decreased availability of O2 to blood Result: Increased  increased tissue O2 carrying ability of demands for O2 blood  other Decreased O2 delivery Enhanced EPO stimulates Kidney (and liver to a erythropoiesis red bone marrow smaller extent) increases RBC releases EPO count EPO 27 EPO levels in response to anemia 28 EPO stimulation of erythropoiesis  EPO interacts with EPO receptor on the plasma membrane (A)  Conformational changes in EPO receptor juxtaposes JAK2 tyrosine kinase molecules resulting in transphosphorylation (JAK = Janus Kinase or “Just Another Kinase”) (B)  Phosphorylated JAK2 phosphorylates the EPO receptor (C)  Phosphorylated EPO receptor and JAK2 recruit and activate (via phosphorylation) signaling molecules leading to changes in gene expression that drives erythropoiesis (D) 29 How is the EPO gene activated by hypoxia?  Hypoxia inducible factor (HIF)  Master regulator of hypoxic gene expression  Transcription factor composed of a and b subunits  >150 genes are regulated by HIF (those involved in erythropoiesis, energy homeostasis, angiogenesis  Underlies central roles in disease (pathway aggressively studied for potential therapeutic targets in cancer and ischemic diseases)  HIF-1 protein is destabilized by O2 and stabilized by hypoxia  Prolines on HIF-1 are hydroxylated (addition of OH) by the O2-dependent enzyme prolyl hydroxylase  Hydroxylated HIF-1 binds to the von Hippel-Lindau (VHL) protein leading to HIF-1 ubiquitination (attachment of ubiquitin protein)  Ubiquitination of HIF-1 targets it for proteasomal degradation 30 HIF-1 regulation by oxygen Front. Endocrinol., 15 August 2018 VHL, von Hippel Lindau; Ub, ubiquitin; PHD, prolyl hydroxylase; and HIF, hypoxia inducible factor 31 HIF-1a stabilization during hypoxia Hypoxia blocks HIF-1a degradation (does not allow for hydroxylation) cytosol HIF-1a RNA polymerase II complex HIF-1a b nucleus Angiogenesis Glucose Erythropoiesis) metabolism 32 Pathway leading to erythrocyte production production 33 Conditions that stimulate and inhibit erythropoiesis 34 Agents that stimulate erythrocyte production  Erythropoiesis-stimulating agents (ESAs)  Recombinant human EPO (rhEPO) administered parenterally  Epoetin alfa (Epogen/Procrit)  Darbepoetin alfa (Aranesp)  HIF prolyl hydroxylase inhibitors  Daprodustat (February 2023 FDA approved for anemia caused by chronic kidney disease in adults on dialysis)  Roxadustat  Vadadustat 35 Erythropoiesis 36 Anemia  Characterized by decreased Hb or decreased circulating RBCs  Hb