Hematopoiesis

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Hematopoiesis

• Masatoshi Kida, MD
• Dept. of Pathology
• University of Vermont

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Hematopoiesisgeneral

• myeloid tissue
• lymphoid tissue

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Hematopoiesisgeneral

• myeloid tissue
• bone marrow
• lymphoid tissue

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Hematopoiesisgeneral

• myeloid tissue
• bone marrow
• erythrocytes
• platelets
• granulocytes
• monocytes
• lymphoid tissue

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Hematopoiesisgeneral

• myeloid tissue
• bone marrow
• erythrocytes
• platelets
• granulocytes
• monocytes
• lymphoid tissue
• thymus
• lymph nodes
• spleen

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Development of Blood Cells

• 3 wk formation of blood islands from yolk sac
• 6 wk liver becomes hematopoietic organ
• 6-8 wk spleen (until 8th month)
• 12-14wk bone marrow (life-long)

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Development of Blood Cells

• 3 wk formation of blood islands from yolk sac
• 6 wk liver becomes hematopoietic organ
• 6-8 wk spleen (until 8th month)
• 12-14wk bone marrow (life-long)
• Bone Marrow
• red marrow
• yellow marrow

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Hematopoiesis
pluripotent stem cell
committed stem cells
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Hematopoiesis
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Normal Marrow Composition
unidentified or disintegrated cells
erythroid precursors
Lymphocytes, monocytes
granulocytes precursors
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Normal Marrow

• myeloid to erythroid ratio 3 1
• dominant myeloid cells
• myelocytes
• metamyelocytes
• granulocytes
• dominant erythroid cells
• polychromatophilic normoblasts
• orthochromic normoblasts

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Myeloblast

• cell division
• 2 of nucleated cells in BM
• size 8-13 mm diameter
• cytoplasm basophilic (many free ribosomes)
  no granules
• nucleus undifferentiated round to
  ovoid coarse nucleoli --gt sieve-like
  appearance

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Promyelocyte

• cell division
• 5 of nucleated cells in BM
• size 20 mm diameter
• cytoplasm deep blue azurophilic granules
  abundant rER, free ribosome numerous
  mitochondria well developed Golgi
• nucleus round to ovoid occasionally
  indented prominent nucleoli

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Myelocyte

• cell division
• 5-20 of nucleated cells in BM
• cytoplasm specific granules decreased in
  basophilia
• nucleus ovoid irregular
  shape disappearing of nucleoli dense and
  compact chromatin

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Metamyelocyte

• no more cell division
• 22 of nucleated cells in BM
• size 10-18 mm diameter (slightly larger than
  mature PMN)
• cytoplasm prominent secondary granules
• nucleus slightly indented, kidney-shaped dens
  e chromatin no nucleolus

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Granulocyte maturation

• stem cell lt0.1
• myeloblasts 2 promyelocytes 5
• myelocytes 5-20
• metamyelocytes 22
• granular leukocytes

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Lifespan of blood cells

• RBC 120 days
• platelet 10 days
• granulocytes circ 9 hours
• tissue days
• lymphocyte circ variable (hours to years)
• tissue weeks to years

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Hematopoietic Microenvironment

• stem cell(s)
• stromal cells
• growth factors
• stimulation

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Hematopoietic Response
hypoxia
infection
antigen
hemorrhage
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Hematopoietic Microenvironment
Stromal cells fibroblasts endothelial
cells adipocytes
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Hematopoietic Growth Factors(SCF, IL-6, GM-CSF,
etc.)

• glycoprotein hormones
• secreted by
• bone marrow stromal cells
• T-cells
• monocytes
• regulate division and differentiation of
  hematopoietic cells
• responsible for basal hematopoiesis and
  maintaining blood counts in normal ranges
• greatly increased secretion in response to
  infection

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Basal Hematopoiesis
G-CSF
SCF stem cell factor GM-CSF granulocyte-macropha
ge colony-stimulating factor G-CSF granulocyte
colony-stimulating factor
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Antigen-amplified hematopoiesis
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Hematopoietic Growth Factors(IL-6, GM-CSF, SCF,
etc.)

• Bacterial viral products
• monocyte

GM-CSF IL-3
T-cell
IL-1 TNFa G-CSF M-CSF
IL-6 GM-CSF G-CSF
Fibroblast Endothelial cell
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Hematopoiesis
ERYTHROPOIESIS GRANULOPOIESIS MEGAKARYOPOIESIS LYM
PHOPOIESIS
GROWTH FACTORS
generation of each specific lineage of mature
blood cells is regulated by a specific set of
hematopoietic growth factors.
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Erythropoiesis

• erythropoietin-independent stage
• GM-CSF
• SCF
• erythropoietin-dependent stage
• erythropoietin

marrow stromal cells IL-3 (activated T-cells)
hypoxia(liver, kidney)
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Granulopoiesis

• early phase
• Neutropoiesis
• Monopoiesis
• Eosinopoiesis
• Basopoiesis,Mastpoiesis

G-CSF
M-CSF
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Megakaryopoiesis

• may also play a role

GM-CSF
IL-3
SCF
IL-6
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Lymphopoiesis

• B-cells
• initial stage
• later stage
• final proliferation and Ab secretion
• T-cells
• CD8 cells
• CD4 cells

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B-cell maturation
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B-cell transformation
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Lymph node
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Spleen
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T-cell transformation
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Markers

• Stem cell CD34, c-kit rhodamine, Hoechst
  dyes (pale)
• B-cell CD19, CD20, (CD22), CD79a
• T-cell CD3, CD2, CD5, CD4/CD8
• NK-cell CD16, CD57, CD56

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RBC variation and irregularity
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anisocytosispoikilocytosis

• anisocytosis (aniso unequal)
• various sizes
• poikilocytosis (poikilo various)
• various shapes

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elliptocytes

• - heredirary elliptocytosis
• - iron def. anemia
• myelofibrosis with myeloid metaplasia
• - megaloblastic anemia
• - sickle cell anemia
• - normal (lt10 of cells)

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spherocytes

• - hereditary spherocytosis
• - acquired hemolytic anemia (e.g. AIHA)
• - physical or chemical injury
• - heat

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leptocytes(target cells)

• - liver disease
• (obstructive jaundice)
• - post splenectomy
• - hemoglobinopathies
• (hypochromic anemias)
• thalassemia
• Hgb C disease
• Hgb H disease

beta thalassemia
relative increase of cell membrane --gt target
formation
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schistocytes(cell fragments)

• indication of hemolysis
• - megaloblastic anemia
• - severe burns
• - traumatic hemolysis
• - microangiopathic hemolytic anemia
  (helmet cells, triangular cells)

helmet cell
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acanthocytes(irregular surface spicules)

• irregularly spiculated cells
• with bulbous/rounded ends of spicules
• - abetalipoproteinemia
• - liver disease

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echinocytes(crenated cells, burr cells)

• regularly contracted cells with smooth surface
  undulation
• - uremia
• - artifact
• - hyperosmolarity
• - discocyte-echinocyte transformation
  (may be associated with reduced ATP of
  RBCs)

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bite cells

• Removal (bites) of membrane by splenic
  macrophages
• - G6PD deficiency

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dacrocytes(teardrop cells)

• - thalassemia
• - myelofibrosis

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drepanocytes(sickle cells)

• - sickle cell anemia

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rouleaux

• lined up RBCs in a row
• - multiple myeloma

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basophilic stippling

• irregular basophilic granules
• (remnants of RNA)
• fine stippling
• increased production of RBCs (reticulocytosis)
• coarse stippling
• lead poisoning
• impaired Hgb syntheisis
• megaloblastic anemia
• other sever anemias

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sideroblast/siderocyte

• inorganic iron-containing granules (Pappenheimer
  bodies)
• - sideroblastic anemia
• abnormally trapped iron in mitochondria forming a
  ring around nucleus
• - post splenectomy

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Howell-Jolly body

• remnant of nuclear chromatin
• single
• megaloblastic anemia
• hemolytic anemia
• post splenectomy
• multiple
• megaloblastic anemia
• other abnormal erythropoiesis

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Heinz bodies

• denatured hemoglobin
• - G6PD deficiency

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leukemoid reaction

• an excessive leukocytic response
• leukocytosis of 50 x109/L or higher
  with shift to the left
• or
• lower counts with considerable numbers of
  immature granulocytes
• quantitative or qualitative changes in
  lymphocytes or monocytes

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leukemoid reaction
hemolysis hemorrhage malignancy Hodgkin
disease myelofibrosis TB burns eclampsia
parasite
infectious lymphocytosis pertussis TB
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leukoerythroblastic reaction
benign hematologic conditions
acute leukemias
hemolysis
myeloprolif dis
misc.
solid tumors lymphomas
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reactive WBC proliferations

• leukocytosis
• (1) increased PMN
• i. increased production
• a. acute inflammation
• - pyogenic bacterial infection
• - tissue necrosis
• ii. increased release of stored RBCs from BM
• a. corticosteroids
• b. stress
• c. endotoxin

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increased PMN

• (1) increased bands (left shift)
• (2) reactive morphologic changes
• a. Döhle bodies (aggregates of rough ER)
• b. toxic granulations (prominent granules)
• c. cytoplasmic vacuoles
• (3) increased leukocyte alkaline phosphatase (LAP)

? neoplasm (CML) decreased LAP
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reactive WBC proliferations

• leukocytosis
• (2) increased eosinophils
• i. allergies asthma (type I hypersensitivity
  reaction)
• ii. parasites
• iii. drugs
• iv. certain skin diseases
• v. cancer (adenocarcinoma)

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reactive WBC proliferations

• leukocytosis
• (3) increased monocytes (monocytosis)
• i. chronic disorders
• a. collagen vascular diseases
• b. inflammatory bowel disease (IBD)
• ii. infection
• a. TB

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reactive WBC proliferations

• leukocytosis
• (4) increased lymphocytes (lymphocytosis)
• i. viral diseases
• a. infectious mononucleosis
• ii. chronic inflammatory process

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infectious mononucleosis

• - one of causes of lymphocytosis
• - a virus-induced disease
• Epstein-Barr virus (EBV)
• CMV

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infectious mononucleosispathophysiology

• (1) EBV invades B-cell via CD21 (CR2)
• (2) cytotoxic (CD8) T-cells respond against
  invaded B-cells

Atypical lymphocytes (Downey cells)
enlargement
CD8 T-cells
Monocyte-like appearance (mononucleosis)
Peripheral condensation of cytoplasm (ballerina
skirt appearance)
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infectious mononucleosis

• (3) heterophil antibody production
• (heterophil antibody antibody against other
  species)
• monospot test (Paul-Bunnell reaction)
• checking for heterophil antibody
• CMV-infectious mono usually heterophil Ab neg

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infectious mononucleosis

• patient population
• adolescents and young adults
• (kissing disease)
• Sx triad plus one
• Fever
• Sore throat (gray-white memb. on
  tonsils)
• Lymphadenitis (post auricular nodes)
• Hepatosplenomegaly
• self-limited clinical course (resolving in 4-6
  wks)

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infectious mononucleosis

• complications
• hepatic dysfunction (hepatitis)
• splenic rupture
• rash (if treated with ampicillin)

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lymphadenopathy

• acute non-specific lymphadenopathy
• tender enlargement of lymph nodes
• bacterial lymphadenitis
• usually focal involvemnt
• may see PMNs within lymph nodes
• stellate microabscesses Cat-scratch Dz
• viral infection
• usually generalized involvement
• reactive T-cell immunoblasts (LN peripheral
  blood)

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lymphadenopathy

• chronic non-specific lymphadenopathy
• non-tender enlargement of lymph nodes
• follicular hyperplasia (B-cells)
• rheumatoid arthritis
• toxoplasmosis
• early HIV infection
• paracortical lymphoid hyperplasia (T-cells)
• viral infection
• drugs (Dilantin)
• systemic lupus erythematosus (SLE)
• sinus histiocytosis (macrophages)

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