Download Blood Cell Development

Belinda Mandrell
Belinda is a Pediatric Nurse Practitioner
and works in the Nursing Research
department at St. Jude. She has over 16
years of experience in pediatric
oncology here at St. Jude. She received
a BSN and MSN from the University
of Maryland. She holds a BS in Public
Health and is a PhD candidate at the
University of Tennessee.
Her research interests are in gene
expression profile and genotype
comparison in pediatric Hodgkin
Disease survivors.
Belinda has numerous journal publications
and several book chapters on Pediatric
Oncology. She has spoken at numerous
conferences in the United States and
Internationally.
1
Blood Cell Development
and Interpretation
Belinda Mandrell, PNP
2
Formation of Blood Cells
Begins in the Bone Marrow with pluripotential
hemopoietic stem cells
Depending upon the body needs, the cell will
become committed and will develop into a
particular cell
As these cells differentiate and grow, they are
assisted by growth inducer proteins
3
Formation of Blood Cells


Growth inducers and differentiation inducers
are extrinsic to the bone marrow
For example: If you have an infection the
growth inducers will stimulate the bone marrow
to increase white cell production
4
Growth Inducers



Four major growth inducers (proteins) have
been described
Interleukin-3: promotes growth and
reproduction of virtually all the different types
of stem cells
The others induce growth of only specific types
of committed stem cells
5
Differentiation Inducers

This is another set of proteins that differentiates
the stem cell one or more steps toward a final
mature blood cell
6
7
Function of Red Blood Cells
AKA “erythrocytes”


Transport hemoglobin, which carries oxygen
from lungs to the tissues of the body
Catalyze the reversible reaction between CO2
and H2O via carbonic anhydrase
 Forms
HCO3-
 Acid-base
balance
8
Production of RBC’s


Early gestation made in yolk sac, then in
liver (small amount by spleen and lymph
nodes)… Last month gestation produced by
bone marrow
Marrow of all bones make RBCs until
approx. age 5 yrs, beyond childhood greatest
production is in the vertebrae, sternum, ribs
and ilia
9
10




CFU-E stimulated to differentiate into
proerythroblasts
Proerythroblasts mature and divide into basophil
erythroblasts (little hgb, have all organelles)
Basophil erythroblast nuclei condense and
endoplasmic reticulum is reabsorbed = reticulocyte
Reticulocytes leave bone marrow, further basophilic
material is reabsorbed, nucleus extruded, increased
hgb is incorporated = mature erythrocyte (within
1-2 days, only 1% retics in circulation)
11
Differentiation
of
RBC’s
•Endoplasmic reticulum
is reabsorbed & nucleus
condenses
•Reticulocytes still
contains small amount
of golgi apparatus,
mitochondria and
nucleus
•Nucleus is extruded
from the cell, increased
hgb content
12
Production of RBC’s


Tissue oxygenation is the most essential
regulator of RBC production
 Anemia, hypoxemia, circulatory failure, high
altitude
Erythropoietin
 Hormone (glycoprotein) 90% released by the
kidney, likely made by tubular epithelium when
PaO2 is low in peritubular capillaries
 Response to catecholamine and prostaglandins
 Some hepatic production 10%
13
14
Erythropoetin



Stimulates hematopoetic stem cells to
differentiate into proerythroblasts
Induces cells to pass through differentiation and
maturation stages more quickly
During times of increase RBC synthesis there
will be a greater percentage or reticulocytes in
circulation
 Marker of bone marrow function
15
Maturation of RBC’s


Vitamin B12 (dependent on dietary intake and
intrinsic factor made by parietal cells of the
stomach)
Folic Acid (dependent on dietary intake)
 Required for formation of DNA
 Decreased DNA synthesis = decreased
nuclear divisions and reduced cell
proliferation / slow reproduction
 Cells
formed are large with fragile
membranes = “macrocytes”
16
Life-Span of RBC’s


90-120 days
Cytoplasmic enzymes metabolize glucose and
produce ATP to keep RBC’s viable
•
Maintains integrity of cell membrane (pliability
and transport of ions)
•
Keeps iron in the ferrous rather than the ferric
state (preventing methemoglobin form which
can not carry oxygen)
•
Prevents oxidation of cell proteins
With aging membrane becomes fragile and RBC’s
lyse (often in red pulp of the spleen)
17
Destruction of RBC’s



After RBC lysis, hemoglobin is phagocytized by
macrophages throughout the body
 Liver Kuppfer cells, spleen & marrow
Macrophages release the iron from the hemoglobin
and pass it back into the blood to be carried by
transferrin (for further production of hgb in marrow
erythroblasts or to liver and other organs to be stored
as ferritin)
Porphyrin is converted to bilirubin, which is released
into blood and then secreted by liver into bile
18
Blood Types


Two antigens (agglutins) occur on the Red Cells
and are classified as Type A and Type B
These antigens are inherited so a person may
have neither of these antigens, have one, or
both.
19
Blood Types




No A or B antigen= Type O
A antigen= Type A
B antigen= Type B
A and B antigens present= Type AB
20
Rh Antigens




Six common Rh antigens but Type D is most
prevalent and is more antigenic that the other
Rh antigens. Persons with this antigen are Rh
Positvie and all others are Rh Negative.
85% of whites are Rh +
95% American Black are Rh+
100% Africian Black are Rh+
21
Erythroblastosis Fetalis



Mother is Rh- and infant is Rh+
Mother develops anti-Rh agglutinins that diffuse
into the placenta causing agglutination of the
fetus’ blood. Red cells hemolyze releasing
hemoglobin. Macrophages convert hem into
bilirubin
Liver and spleen enlarge producing red blood
cells
22
Erythroblastosis Fetalis


Infants die from anemia or have mental
impairment from increased bilirubin
Treatment:Exchange transfusion with Rh-blood.
23
Platelets






Formed from precursor megakaryocytes
No nuclei, use mitochondria to form ADP / ATP,
life-span 8-12 days / cleared by spleen macrophages
Contain the contractile proteins actin, myosin &
thrombosthenin
Secrete enzymes, prostaglandins, hormones and
calcium ions
Synthesize fibrin-stabilizing factor protein
Secrete growth factor that encourages vascular
endothlium, smooth muscle and fibroblasts to
regenerate
24
Characteristic of Platelets Cont ...

Specialized cell membranes
 Glycoproteins prevent adherence to normal
endothelium of blood vessels … platelets selectively
adhere to damaged blood vessels with exposed
collagen
 Large volume of phospholipids
 Activating roles in clot formation
25
Conditions That Cause Excessive
Bleeding
Liver Disease: All clotting factors are formed in
liver
Vitamin K deficiency: Vit K is needed for liver
formation of prothrombin, factor VII, IX, and
X. Vit K is synthesized by bacteria in the GI
Tract.
26
Bleeding


Hemophilia: Genetic deficiency of factor VIII
or IX
Thrombocytopenia will result in bleeding within
small venules or capillaries rather than large
vessels
27
Immune System Overview


System of eradicating infectious organisms
(and toxic substances) from the body
White Blood Cells
 Destroy invading bacteria or virus by
phagocytosis
 Form antibodies and sensitized
lymphocytes which destroy or inactivate
invaders
28
White Blood Cells



AKA “leukocytes”
Mobile units of the body’s protective system
Formed in bone marrow
 granulocytes, monocytes and some
lymphocytes
Formed in lymph tissue
 Lymphocytes and plasma cells
29
Types of WBC’s

Polymorphonuclear neutrophils

Polymorphonuclear eosinophils

Polymorphonuclear basophils

Monocytes

Lymphocytes

Plasma Cells
Granulocytes
or “Polys” have multiple
nuclei
30
Normal Concentrations of WBC’s

Neutrophils
50-60%

Eosinophils
2-3%

Basophils
0.5-1%

Monocytes
5-10%

Lymphocytes
20-40%
31
Infant White Blood Cell Counts

Newborns may have total count of 30,000 –
40,000

Throughout first year of life gradually decreases
to adult levels
32
Production of WBC’s



Pluripotential hematopoetic stem cells
differentiate into committed stem cells
Committed stem cells further differentiate into
RBC’s and WBC lineages
WBC lineages or Colony Forming Units CFU’s
 Myelocytic - myeloblasts
 Granulocytes & monocytes (formed in bone
marrow)
 Lymphocytic - lymphoblasts
 Lymphocytes & plasma cells (formed in lymph
tissue)
33
34
Differentiation
of
WBCs
35
Life Span of WBCs



Formed and stored until needed
Approximately 6 day supply
Granulocytes:
 Survive in blood 4-8 hours
 Survive in tissue 4-5 days
Monocytes:
 Spend 10-20 hours in blood then deposit in
tissue = tissue macrophages which survive for
months
Lymphocytes stored in lymph tissue / pass in and
out of blood
 Survive weeks to months
36
Neutrophils & Macrophages





Destroy invading microorganisms via phagocytosis
Enter tissue spaces via diapedesis
Move through tissues spaces by ameboid like motions
Neutrophils are mature WBC’s in circulating blood
Macrophages were circulating blood monocytes that
matured after moving into a tissues
37
Chemotaxis of
Neutrophils & Macrophages


Chemical substances attract neutrophils and
macrophages to a site of injury / inflammation
 Bacterial and viral toxins
 Cytokines
 Complement proteins
 Clotting proteins
Associated with increased capillary membrane
permeability to facilitate movement of the WBCs
from the blood into tissue spaces
38
Phagocytosis


Cellular ingestion of an offending agent
Selection of offending agent:
 Rough surface (healthy tissues of the body have
smooth cell membranes)
 Lack of protein coats (healthy tissues of the body
have protein coats that repel phagocytes - dead
and foreign materials do not)
 Antibodies produced by lymphocytes coat the
pathogens and make then susceptible to
phagocytosis (Antibody + C3 protein =
opsonization)
39
Phagocytosis Continued...



WBC contacts the pathogen and extends
pseudopodia to attach and encircle organism
Fuse to enclose organism in a phagocytic
vesicle or phagosome within it’s cytoplasm
Lysosomes and other cytoplasmic granules fuse
with phagosome and release digestive and
bactericidal enzymes into the phagosome =
digestive vesicle
40
Phagocytic Chemicals



Proteolytic enzymes - proteases
 Break down proteins
Lipases
 Break down lipids and phospholipids
Bactericidal agents
 Kill bacteria when enzymes fail to digest them
 Oxidizing agents from peroxisomes
 Superoxide (O2-)
 Hydrogen peroxide (H2O2)
 hydroxyl ions (OH-)
 Myeloperoxidase catalyzes H2O2 + Chloride
= hypochlorite
41
Monocyte-Macrophage

Monocytes, fixed tissue macrophages, mobile
macrophages and specialized endothelial cells in
the bone marrow, spleen and lymph nodes make
up the reticuloendothelial system

Fixed tissue macrophages break away and move
with strong chemotaxis signal = delay in
immediate response to infection (will see
increased number of circulating neutrophils in
blood stream before increases in monocyte line)
42
Skin & Subcutaneous Tissue
Macrophages

Histiocytes

Second line of defense if skin / subcutaneous
tissue is exposed to external environment

Histiocytes will divide in-situ in response to local
inflammation
43
Brain Macrophages

Microglial cells

Interlaced with neurons in the central nervous
system
44
Macrophages of the Lymph Nodes

Microorganisms in tissue do not move through
capillary membrane into the blood stream, but can
still be filtered by the lymph system
Lymph nodes
Macrophages line the lymph
nodes’ sinuses
Organism is
destroyed before efferent
leads to venous blood
45
Macrophages in the Liver Sinusoids



Kupffer Cells
Interlaced with epithelial cells of the sinusoids
Bacteria in the portal
circulation are
eradicated before
entering the systemic
circulation
46
Macrophages of the
Spleen and Bone Marrow



Act on microorganisms that enter the blood
stream
Macrophages are entrapped by a reticular
meshwork
Blood flows
through the
spleen’s red pulp which
contains the
macrophages
47
Macrophages of the Lungs




Large number of tissue macrophages are
embedded in alveolar walls
Phagocytize pathogens that are inhaled into the
lungs
After digestion of a pathogen, alveolar
macrophages dump product into lymph system
When a pathogen is difficult to digest, many
macrophages group together to form a “giant
cell” that digests the pathogen over time
(common in TB, noxious dust)
48
Neutrophils & Macrophages and the
Inflammatory Response


Inflammation
At site of insult (injury / infection)
•
Vasodilation (erythema)
 Histamine, bradykinin, prostaglandin, nitric
oxide
•
Increased capillary membrane permeability
 Edema
•
Initiation of clotting cascade
•
Infiltration of WBCs (monocytes and
granulocytes)
49
The “Walling-Off ” Effect of
Inflammation

The tissue spaces and lymphatics are blocked
by fibrin clots

Prevents / delays spread of microorganisms,
toxins and inflammatory mediators
50
Neutrophil & Macrophage Responses
During Inflammation


First line = tissue macrophages at site of insult
 Begin phagocytosis
Second line = neutrophils move via chemotaxis and
infiltrate the site
 Margination
– neutrophils alter endothelium to cause
sticking of WBC’s to capillary wall
 Vessel membranes become more porous to allow
additional WBCs to infiltrate the site
 Trigger release chemotaxis signals
51
Neutrophil & Macrophage Responses
During Inflammation Cont…



Within hours, excessive numbers of neutrophils enter
blood from the marrow (neutrophilia … “left shift”)
 When bone marrow is hyper-active, immature
forms of WBCs or “bands” may enter blood
Next, monocytes enter blood from marrow
 Many begin deposition into tissue and maturation
into macrophages, others remain in blood as
monocyte reserves
In the later stages of infection, monocytes may
predominate the WBC count
52
Feed-back Control of
Neutrophil & Monocyte Responses

Chemical control
 Cytokines
 Tumor Necrosis Factor (TNF)
 Interleukin-1(IL-1)
 Granulocyte-Monocyte Colony Stimulating
Factor (GM-CSF)
 Granulocyte Stimulating Factor (G-CSF)
 Monocyte Colony Stimulating Factor (MCSF)
53
Formation of Pus



Neutrophils and macrophages die after they
phagocytize pathogens and necrotic tissue
After several days, a cavity containing the
dead tissue cells, neutrophils and
macrophages and interstitial fluid may form
within tissue = pus
Usually reabsorbed over time, but persistent
cavitation - abscess
54
Eosinophils


Eradicate parasitic infection
 Attach to parasites via surface molecules and
secrete toxic substances into the parasite
 Hydrolytic enzymes released by granules or
modified lysosomes
 Oxygen free radicals
 Major basic protein: larvicidal
polypeptide
Allergic reactions
 Along with mast cells and basophils that release
eosinophil chemotactic factor
55
Basophils

Contribute to allergic responses to antigens
 Release histamine and heparin (similar to mast
cells that lie outside of capillaries)
 Also release bradykinin, serotonin, slow releasing
substance of anaphylaxis
 Local vascular reactions (vasodilation and
capillary leak with erythema and edema)

IgE type antibodies become attached to basophils
(and mast cells) as part of the trigger for an allergic
response
56
Innate Immunity




Phagocytosis of microorganisms by neutrophils
and macrophages
Destruction of swallowed organisms by HCL in
the stomach and digestive enzymes
Resistance of skin to invasion by microorganisms
Chemical substances in the blood that attach to and
destroy microorganisms
 Lysozymes
 Basic polypeptides
 Complement complex
 Natural killer lymphocytes
57
Acquired immunity



Humoral Immunity or B-cell immunity
 Antibodies
Cell-mediated Immunity or T-cell immunity
 Activated T-Lymphocytes
Activated by antigens
 Polysaccharide / protein patterns (sterochemical
characteristics) on outer surface of a foreign
substance
 Epitope
 Haptens
 Small molecules that combine with other
proteins in the body to create an antigen
58
The Basis of Acquired Immunity:
Lymphocytes


Pluripotential hematopoietic stem cells form
undifferentiated lymphocytes
 Lymphocytes destined to be T-lymphocytes
travel to the thymus, where they are processed
 B-lymphocytes (responsible for antibodies) are
pre-processed in the liver and marrow
Lymphocytes then migrate to lymph nodes, spleen,
sub-mucosa of the GI tract, or remain in bone
marrow
 Sites of immediate exposure to antigens
59
The Basis of Acquired Immunity:
Lymphocytes


Pluripotential hematopoietic stem cells form
undifferentiated lymphocytes
 Lymphocytes destined to be T-lymphocytes
travel to the thymus, where they are processed
 B-lymphocytes (responsible for antibodies) are
pre-processed in the liver and marrow
Lymphocytes then migrate to lymph nodes, spleen,
sub-mucosa of the GI tract, or remain in bone
marrow
 Sites of immediate exposure to antigens
60
Pre-processing of the T-lymphocytes in
the Thymus Gland





In the thymus gland, maturing T-lymphocytes
interact with various antigens
Each cell develops reactivity toward a specific
antigen
The cells divide rapidly
Any lymphocytes that develop reactivity toward
a “self antigen” are destroyed in the thymus
This process occurs most intensely during the
first year of life
61
Pre-processing of the B-lymphocytes by
the Liver and Bone Marrow



Pre-processing occurs during mid and late fetal life, as
well as after birth
After exposure to antigens, the B-lymphocytes make
antibodies specific to the antigen
On subsequent exposure to the antigen, the Blymphocytes secrete an antibody

Antibodies are proteins capable of destroying the
antigenic organism via chemical reactions
62
63
Lymphocyte Clones





Stimulated lymphocytes reproduce extensively
The progeny of the original lymphocyte are called
“clones”
The stimulated lymphocyte created new gene
segments that were not part of its original DNA
prior to processing
These new genes, code for the antibody protein
of B-lymphocytes or the surface receptor
proteins of T-lymphocytes
The clones formed automatically have these
genes
64
Role of T-cells in
Activating B-lymphocytes




Most antigens activate both B and T lymphocytes
T-helper cells (a line of t-cell clones) are activated
and secrete lymphokines
Lymphokines activate the antigen specific Blymphocytes
Without the T-helper cells, only a small number of
antigen specific B-lymphocytes would be activated
by the presence of the antigen
Increases antibody production
65
Formation of Antibodies by
Plasma Cells

Activated B-lymphocytes (clones) hypertrophy
and take on characteristics of lymphoblasts (can
further differentiate, as though they were immature
forms)

Some lymphoblasts differentiate into
plasmablasts, or the precursors of plasma cells

The mature plasma cell produces antibodies
which is secreted into the lymph tissue and carried
to the circulating blood
“Primary Response”
66
Formation of “Memory” Cells




Some lymphoblasts differentiate into new Blymphocytes called memory cells (instead of
plasma cells)
Memory B-cells leave lymph tissue and circulate
throughout the body and lay dormant in various
tissues
On subsequent exposure to the antigen, they very
quickly respond and produce antibodies to the
antigen
The wide-spread location allows for activation at
multiple sites of infection
“Secondary Response”
67
Antibody Production
68
Role of Macrophages in the Activation
of Lymphocytes




Macrophages are also present in the lymphoid tissue
that houses lymphocytes
Organisms invading the lymph tissue are first
phagocytized by the macrophages
After partial digestion, the antigenic polysaccharides
/ proteins of the organism is liberated into the
macrophage cytosol
The macrophages then pass the antigenic
substance to adjacent lymphocytes
 Creates a new antigen specific lymphocyte or
stimulates a B memory cell
69
The Nature of Antibodies

Antibodies are
gamma globulins
called
immunoglobulins

Variable portion is
antigen specific

Constant portion
facilitates
interaction with
other immune
enhancers
70
Classes of Antibodies
The Immunoglobulins





IgM
 Immunoglobulin during primary responses,
has 10 binding sites = increased efficacy
IgG
 Constitutes 75% of antibodies and is bivalent
IgA
 Secretory antibodies
IgE
 Involved in allergy
IgD
71
Mechanism of Action of Antibodies




Agglutination
 Clumping of multiple particles with the antigen
together to increase efficacy of eradication
Precipitation
 Making a dissolved antigenic molecule a solid, so
that it can be trapped, agglutinated etc…
Neutralization
 Antibodies cover the toxic sites of the antigenic
molecule (i.e.: endotoxins of bacteria)
Lysis
 Direct attack of cell membranes of the antigenic
molecule causing rupture and death
72
The Complement System





System of 20 proteins / enzyme precursors
normally present in the blood in inactive forms
The Classic Pathway
Activated by antigen-antibody complex, which
uncovers an active site on the constant portion
of the antibody
The antibody binds with C1 (complement protein
number 1)
C1 enzymes are activated and a successive cascade
of reactions takes place
An amplified immune response results
73
Effects of Complement Activation

Opsonization and Phagocytosis (C3b)


Lysis (C5b6789)





activates phagocytosis by neutrophils
Lytic complex– direct membrane rupture
Agglutination
Neutralization of Viruses
Chemotaxis (C5a)
Activation of Mast Cells and Basophils (C3a,
C4a and C5a)
Inflammatory response is amplified
74
Activated T-cells and
Cell-Mediated Immunity



Activated antigen-specific T-cells leave the
lymph tissue and enter the circulation
Activated T-lymphocyte memory cells are
produce similarly to B memory cells (via
lymphoblast differentiation during first
exposure to antigen)
Memory T cells contribute to a rapid secondary
response and are widely distributed throughout
the body
75
Lymphocyte
Surface Receptor Proteins




Antigen specific receptors present on tlymphocyte clones that have differentiated into
T-memory cells
May be 100,000 receptor sites on a single T-cell
Attach to invading antigen as part of the
secondary response
Multiple types with multiple responses to
activation
76
Helper T-Cells






Most numerous type of T-cell
Lymphokines (IL2-6, GM-CSF, interferon)
Stimulate of Cytotoxic T-cells and Suppressor Tcells (via activity of IL-2)
Stimulate B-cell to form plasma cells and
antibodies (IL 4,5,6 and B-cell stimulating factor /
B-cell growth factor)
Activate macrophages and prevent migration of
macrophages away from site of insult
Feedback stimulation to continue production and
function of other helper T-cells (IL-2)
77
Helper
T-Cells
78
Cytotoxic T-cells


Killer T-cells
Directly attack antigenic molecules
 Secrete digestive enzymes
 Secrete cytotoxic substances …such as
 Hole forming proteins or perforins
 Causes fluid influx and lysis of
pathogen cells
79
Killer T-Cells
80
Suppressor T-cells




Regulatory T-cells
Suppress the function of both cytotoxic
and helper T-cells
Modifies immune response
Prevents erratic systemic inflammation and
auto-immunity
 “immune tolerance”
81
Allergy



Immune response to non-toxic or infectious
agents
Delayed reaction allergy is mediated by T-cells
 Repeated exposure = increasingly amplified
“secondary response”
Excess IgE antibodies is mediated by B-cells
 Called reagins or sensitizing antibodies
 Strong propensity to attach to mast cells and
basophils
 Inflammatory mediators released from
granules
82
Origins of Agglutinins



Gamma globulins (just like any other antibody),
mostly IgM and IgG forms
Small amounts of A and B antigens enter the body
in food and bacteria and stimulate the formation of
the antibodies in individuals who do not possess
the antigen proteins on their RBC’s
Immediately after birth, neonates have almost no
agglutinins… as the child is exposed during the
first 8 months of life, these antibodies are formed
(max titer at 8-10 yrs, then decline)
83
Tissue Typing



Antigens on organ cell membranes and WBC’s
= HLA Type
Six basic types, with 150 different variations =
over a trillion combinations (only identical twins
have the EXACT same antigen patterns
throughout the body)
When one of these antigens is not present, an
individual may develop antibodies to it on
exposure = graft rejections after organ or bone
marrow transplants
84