Download Blood = formed elements + plasma

Blood = formed elements + plasma
If blood is removed from the circulatory system, it will clot. This clot
contains formed elements and a clear yellow liquid called serum,
which separates from the coagulum.
The hematocrit - the volume of packed erythrocytes per unit volume
of blood. The normal value is 40–50% in men and 35–45% in women.
Humans contain about 5 liters of blood, accounting for 7% of body weight
Proteins of plasma
Hemoglobin molecule
adult hemoglobin
a large protein composed of
four polypeptide chains, each
of which is covalently bound
to a heme group
fetal hemoglobin (HbF) is
composed of two α-chains
and two γ-chains (α2γ2)
96% of adult hemoglobin is
HbA1 (α2β2)
Formed elements (= blood cells)
(RBC)
granulocytes
agranulocytes
(WBC)
Cells of the peripheral blood
(Thrombocytes)
Cells of the peripheral blood
Plasma - contents
Preparation of a blood smear
Erythrocytes (red blood cells, RBC)
RBC
Capillary endothelial cell
Е = erythrocyte (RBC)
Arrow – platelet
Erythrocytes are biconcave disks without nuclei
7.5 µm in diameter
2.6 µm thick at the rim
0.8 µm thick in the center
macrocyte - diameter greater than 9 µm
microcytes - diameter less than 6 µm
anisocytosis - high percentage of erythrocytes with great
variations in size is called (Gr. aniso, uneven, + kytos).
Erythrocytes in pulmonary capillaries
alveolus (air)
capillary
capillary
alveolus (air)
RBC life cycle
• Human erythrocytes survive in the circulation
for about 120 days. Worn-out erythrocytes are
removed from the circulation mainly by
macrophages of the spleen and bone marrow.
RBC stability
A red blood cell is pushed and deformed with laser tweezers. It
quickly springs back to its original shape because it has an extremely
tough cytoskeleton to which the plasma membrane is anchored.
From Alberts et al, Molecular Biology of the Cell
The structural support of the RBC
plasma membrane
Promotion of Membrane Flexibility
and Stability
Limitation of Lateral Diffusion
of Membrane Proteins
Spectrin-based
Cytoskeleton
Spectrin Molecule
From Alberts et al,
Molecular Biology of the Cell
Spectrin-based Cytoskeleton - EM
ASA links
Ankyrin
Spectrtin
Actin
From Alberts et al,
Molecular Biology of the Cell
The Spectrin-based Cytoskeleton of the RBC
~ 220 kDa
~ 180 kDa
~ 100 kDa
~ 80 kDa
Transmembrane
Endoperipheral
Glycophorins
Band 3
Ankyrin
Adducin
Band 4.1
~ 40 kDa
Spectrin
Intracellular
Actin
Electrophoresis of RBC Membrane
Спектрин-базирани цитоскелетни комплекси
осигуряват стабилността на еритроцитната
мембрана
From Alberts et al,
Molecular Biology of the Cell
Спектрин-базирани цитоскелетни комплекси
Clinical correlates of the RBC cytoskeleton
• Glycophorin A – entry of Influenza & Hepatitis virus, P. falciparum
• Band 4.1 – MN blood groups
• Band 3
• Ankyrin
• Spectrin
Hereditary spherocytosis (HS)
Hereditary elliptocytosis (HE)
• Band 3
Southeast Asian ovalocytosis (SAO)
Distal renal tubular acidosis (dRTA)
Hereditary Spherocytosis (HS)
Autosomal Dominant
1/5000 in N.America
Normal smear
HS smear
Hereditary Spherocytosis (HS)
SEM
Normal RBC
HS RBC
Clinical Presentation of RBC Membrane Defects
Mutations in cytoskeletal genes
Weakened interactions among cell membrane proteins
Weakened structure of RBC membrane
Spherical RBC
Increased RBC destruction in the spleen
Hemolytic anemia
Jaundice
Anemia = reduced Hb
disturbance in DNA synthesis
disturbance in
Hb synthesis
disturbance in Hb
synthesis; lack of iron
HbS
abnormal
globin chain
membrane defect
membrane defect
mechanical damage
to erythrocytes
membrane lipid defect,
e.g., abetalipoproteinemia
abnormal globin chain
Rubin, Reisner, Essentials of Rubin's Pathology, 5th Edition
ABO blood group system
The extracellular surface of the red blood cell plasmalemma has specific inherited
carbohydrate chains that act as antigens and determine the blood group of an individual
for the purposes of blood transfusion. The most notable of these are the A and B
antigens, which determine the four primary blood groups, A, B, AB, and O
Other - Rhesus, MNS, Lutheran, Kell, Lewis, Duffy, Kidd, Diego, Cartwright, Colton, Sid,
Scianna, Yt, Auberger, Ii, Xg, Indian and Dombrock systems.
Granulocytes - nuclei with two or
more lobes
Granulocytes (L. granulum, granule, + Gr. kytos)
Contain 2 types of granules
specific granules → specific functions
azurophilic granules → lysosomes
Nondividing terminal cells with a life span of a few
days
Die by apoptosis (programmed cell death) in the
connective tissue
Few mitochondria (low energy metabolism) →
depend mostly on glycolysis
Neutrophilic granulocyte
Golgi complex, Rough endoplasmic reticulum
and mitochondria are not abundant → the cell
is in the terminal stage of its differentiation
12–15 µm in diameter
2-5 lobes linked by fine threads
of chromatin
short-lived cells with a half-life
of 6-7 h in blood and a life span
of 1-4 days in connective tissues
Granules of neutrophils
Specific Granules
Alkaline phosphatase
Collagenase
Lactoferrin
Lysozyme
Several nonenzymatic antibacterial
basic proteins
Azurophilic Granules
Acid phosphatase
-Mannosidase
Arylsulfatase
Arylsulfatase
-Galactosidase
-Glucuronidase
Cathepsin
5'-Nucleotidase
Elastase
Collagenase
Myeloperoxidase
Lysozyme
Cationic antibacterial proteins
Eosinophilic granulocyte
The specific granules have a crystalline core
(internum) & outer externum, or matrix. The
internum contains a protein called the major
basic protein to which the eosinophilia
accounts.
12–15 µm in diameter (same as
neutrophils
2 lobes
large specific granules (about 200 per
cell) stained by eosin
found in the connective tissues
underlying epithelia
Participate in anti-parasitic immunity
Basophilic granulocyte
The lobulated nucleus appears as several separated
portions. Note the basophilic granule (arrows),
12–15 µm in diameter (same as
neutrophils & eosinophils)
metachromatic specific granules →
heparin (also histamine)
migrate in the connective tissues,
similarly to mast cells
participate in allergy
Monocyte
Kidney-shaped nucleus. Azurophilic
granules (arrows).
12–20 µm in diameter (larger than
granulocytes)
very fine azurophilic granules →
lysosomes
migrate in the connective tissues, to
become tissue macrophages
precursor cells of the mononuclear
phagocyte system → not terminal cells
Monocyte differentiation in various tissues
Cell Type
Location
Main Function
Monocyte
Blood
Precursor of macrophages
Macrophage
Connective tissue, lymphoid organs, lungs,
bone marrow
Inflammation (defense), antigen processing and
presentation
Kupffer cell
Liver
Same as macrophages
Microglia cell
Nerve tissue of the central nervous system
Same as macrophages
Langerhans cell
Skin
Antigen processing and presentation
Dendritic cell
Lymph nodes
Antigen processing and presentation
Osteoclast
Bone (fusion of several macrophages)
Digestion of bone
Multinuclear giant cell
Connective tissue (fusion of several
macrophages)
Segregation and digestion of foreign bodies
Function of monocytes/macrophages
Phagocytes → granulocytes & monocytes
macrophage
monocyte
Phagocytes participate in the anti-bacterial
immunity
Penetration of bacterial cells
releases chemotactic factors
Chemotactic factors
activate phagocytes
Phagocytes engulf
bacteria
Diapedesis – phagocytes
migrate from blood to tissue
Chemotaxis - attraction of specific cells by chemical mediators
Migration in
tissues is
associated
with change
in cell shape
Bacterial phagocytosis by neutrophils
1. Recognition
2. Endocytosis
Hydrolytic
enzymes
Specific receptor
Specific receptor
bacteria
bacteria
3. Degradation
Leukocyte Extravasation
Overview
• Rolling (tethering)
• Activation
• Adherence
• Diapedesis (extravasation)
From Alberts et al, Molecular Biology of the Cell
Leukocyte Extravasation
Main Steps
• Rolling (tethering)
reversible binding of leukocytes to endothelial cells
mediated by selectins and glycosylated ligands
• Activation
stimulation of the leukocyte by chemokines
result – increase in integrin α4β1 (VLA-4) activity
binding of integrin to its endothelial partner (VCAM-1)
• Adherence (tight adhesion)
irreversible adhesion mediated by integrins & Ig family
αLβ2 (LFA-1) on leukocyte with ICAM-1 on endothelial cell
• Diapedesis (extravasation)
transmigration of leukocyte between endothelial cells
involves αVβ3 on leukocyte with PECAM on endothelial cell
Progressive integrin activation in
leukocyte extravasation
PECAM
activation → adherence → diapedesis
integrin β1
→
β2
→
β3
Leukocyte Diapedesis Through Endothelial Junctions
• VE-cadherin tends to redistribute to the endothelial surface
• PECAM&JAMs are concentrated along the endothelial cell borders
• CD99, a membrane protein that is present in endothelial cells and
leukocytes, functions independently in directing leukocyte diapedesis
through the cleft.
Blocking both PECAM and CD99 leads to inhibition of diapedesis.
From Dejana, Nat Rev Mol Cell Biol 2004;5:261
Leukocyte Adhesion Deficiency (LAD) Syndromes
• LAD I syndrome – β2 integrin deficiency
leukocyte adherence deficiency
recurrent severe infections
in worst cases patients dies by age of 10
• LAD II syndrome – selectin deficiency
leukocyte rolling deficiency
infections rare, developmental abnormalities
(growth retardation, neurologic deficits)
Chemokines are chemotactic cytokines
• Small (8-10 kDa) proteins, over 40 known to date
• Families
CXC – the first 2 cysteins are separated by 1 amino acid
CC – the first 2 cysteins are separated by 0 amino acids
CXXXC – the first 2 cysteins are separated by 3 AAs
C – has only 2 cysteins
• Examples
CXC – IL-8
CC – MIP, MCP
CXXXC – fractalkine
C – lymphotactin
From Luster,
N Eng J Med 1998;338:436
Lymphocyte
large (diameter 6-8 µm)
small (diameter 6-8 µm)
ER
ER
larger lymphocytes → cells activated
by specific antigens
scant cytoplasm, a few azurophilic
granules
the only type of leukocytes that
return from the tissues back to the
blood
variable life span: days – years
80% of the circulating lymphocytes
are T cells, 15% are B cells, and the
remainder are null cells (NK or
circulating stem cells)
Resting & activated lymphocytes
little RER
Molecular Biology of the Cell (© Garland Science 2008)
→
rich RER
Surface antigenic characteristics of
lymphocytes – CD (cluster of differentiation)
Immunglobulin-“superfamily”
Surface
markers are
detected by
flow cytometry
Thrombocyte (platelet)
Platelet
Е = erythrocyte
(RBC)
Arrow – platelet
RBC
Endothelial capillary cell
nonnucleated, disk-like, 2-4 µm in diameter
2 main regions
peripheral → hyalomere
central → granulomere
participate in the clotting of the blood
life span – 10 days
Platelet tubules and granules
Platelet activation → changes in cell shape
From Alberts et al, Molecular Biology of the Cell
Platelets & blood clotting
red – erythrocytes
blue – platelets
yellow - fibrin
Summary - Products and functions of
blood Cells
Hemopoiesis (Gr. haima, blood, +
poiesis, a making) )
Prenatal hemopoiesis
mesoblastic phase (2 wk after conception) – blood islands in
the mesoderm of the yolk sac; only RBC
hepatic phase (6th week of gestation) - leukocytes appear by
the 8th week
splenic phase (2nd trimester)
myeloid phase (end of 2nd trimester) – bone marrow
Postnatal hemopoiesis - occurs almost exclusively in
bone marrow, but the liver and the spleen can revert to
forming new blood cells if the need arises
Prenatal hemopoiesis
Stem cells → progenitor cells → precursor cells
Stem cell populations in the bone marrow
Pluripotential hemopoietic stem cells (PHSCs)
multipotential hemopoietic stem cells (MHSCs)
about 0.1% of the nucleated cells in bone marrow
can produce themselves or multipotential hemopoietic stem
cells (MHSCs)
responsible for the formation of various progenitor cells
CFU-GEMM cells – colony forming unit for granulocyte,
erythrocyte, monocyte, megakaryocyte
CFU-Ly cells – colony forming unit for lymphocytes
PHSCs & MHSCs are morphologically indistinguishable,
resemble lymphocytes and constitute a small fraction of
the null-cell population of circulating blood
CD34+ colonies of progenitors
Researchers studying hemopoiesis have isolated individual
lymphocyte-like cells that, under proper conditions, occasionally
give rise to groups (colonies) of cells composed of granulocytes,
erythrocytes, monocytes, lymphocytes, and platelets → such cells
are called colony-forming units (CFUs)
Progenitor cell populations in the bone marrow
Morphologically indistinguishable from stem cells,
resemble lymphocytes like stem cells
Can be differentiated only by CD expression
Unipotential → committed to forming a single cell line,
responsible for the formation of various progenitor cells
CFU-E cells – erythroid lineage
CFU-Meg cells – platelet lineage
CFU-Eo cells – eosinophil lineage
CFU-B cells – basophil lineage
CFU-GM cells – neutrophil & monocyte lineages
CFU-LyT cells – T lymphocytic lineage
CFU-LyB cells – T lymphocytic lineage
Limited capacity for self-renewal → depend on stem cells
for renewal
Hemopoietic Growth Factors
(Colony-Stimulating Factors)
Glycoproteins acting on specific stem cells, progenitor
cells, and precursor cells, generally inducing rapid
mitosis, differentiation, or both
Routes to deliver growth factors to their target cells:
transport via the bloodstream (as endocrine hormones)
secretion by stromal cells of the bone marrow near the
hemopoietic cells (as paracrine hormones)
direct cell-to-cell contact (as surface signaling molecules)
GMSCF, granulocyte-monocyte
colony-stimulating factor
Growth factors & cytokines regulating hemopoiesis
Precursor cell populations in the bone marrow
Arise from progenitor cells
Have specific morphological characteristics → permit
them to be recognized as the first cell of a particular cell
line
/cell name/-blast: e.g. erythroblast, myeloblast
pro-/cell name/-cyte
/cell name/-cyte
meta-/cell name/-cyte
Incapable of self-renewal
Undergo cell division and differentiation → give rise to
a clone of mature cells
Changes in properties of hematopoietic cells
during differentiation
Succeeding cells become smaller, their nucleoli disappear, their chromatin
network becomes denser, and the morphological characteristics of their
cytoplasm approximate those of the mature cells
Erythroid & granulocytic lineages
normoblast
azurophilic
granules
nonnucleated
Erythrocyte maturation
General features
cell volume decreases
nucleoli diminish in size
nuclear diameter decreases
chromatin becomes more dense
→ pyknotic → extruded from
the cell
mitochondria and other
organelles gradually disappear
Erythroid cells
Polychromatophilic erythroblast
rthochromatophilic
erythroblast
rythrocyte
Reticulocyte
roerythroblast
rythrocyte
asophilic erythroblast
Each day, the average adult produces approximately 2.5 × 1011 erythrocytes
Characteristics of the cells of the
erythroid lineage
normoblast
A developing red blood cell
(erythroblast) extrudes its
nucleus to become an immature
erythrocyte (a reticulocyte),
which then leaves the bone
marrow and passes into the
bloodstream
Neutrophilic lineages
Myeloblast → the most
immature recognizable cell
Myelocyte → first sign of
differentiation
Characteristics of the cells of the
neutrophilic lineage
Each day, the average adult produces approximately 800,000 neutrophils, 170,000 eosinophils, and 60,000 basophils
Lymphocyte development
Development of lymphocytes
lymph nodes, spleen
lymphocyte progenitors → bone marrow
T cells maturate in the thymus
B cells maturate in bone marrow &
peripheral lymphoid organs
Molecular Biology of the Cell (© Garland Science 2008)
Lymphocytes can be distinguished only by
differential surface marker expression
Monocyte development
Dendritic cells arise from both the myeloid
and lymphoid lineages
Smears from bone marrow vs peripheral blood
Bone marrow
Much more nucleated cells
Peripheral blood
Leukemias – disorders of the hematopoietic progenitors
bone
Normal bone marrow
Leukemia
Acute myeloblastic leukemia results from uncontrolled mitosis of a transformed stem cell whose
progeny do not differentiate into mature cells. The cells involved may be the CFU-GM, CFU-Eo, or
CFU-Ba, whose differentiation stops at the myeloblast stage.
Leukemias – disorders of the hematopoietic progenitors
Lymphoblastic leukemia
Myeloblastic leukemia
Normal
Leukemia & lymphoma can be typed
according to CD expression
B cell lymphoma
T cell lymphoma
Development of platelets
Megakaryoblasts
1 nucleus with many lobes & numerous nucleoli
undergo endomitosis → up to 64 N (polyploid)
(
Megakaryocytes (Gr. megas, big, + karyon,
nucleus, + kytos)
giant cells (35-150 µm in diameter)
irregularly lobulated nucleus, coarse chromatin,
and no visible nucleoli
numerous invaginations of the plasma membrane
→ areas that shed platelets
Megakaryocytes in the bone marrow
Megakaryocyte fragmentation
The passage of erythrocytes, leukocytes,
and platelets across a sinusoid capillary
in bone marrow
The immune system
Innate immunity
activated immediately after an infection begins
do not depend on the host’s prior exposure to the pathogen
present in all multicellular organisms
components: complement, antimicrobial peptides,
macrophages, neutrophils, NK cells, Toll-like receptors
(TLRs)
Adaptive immunity
operate later than the innate response
highly specific for the pathogen
present only in vertebrates
components: T cells, B cells, antigen-presenting cells (APCs),
immunoglobulins, cell-mediated immunity components
The immune system
protective barriers, toxic molecules, and phagocytic
cells that ingest and destroy invading microorganisms
(microbes) and larger parasites (such as worms).
lymphocytes
Molecular Biology of the Cell (© Garland Science 2008)
Innate immune system leads to the activation
of the adaptive immune system
Molecular Biology of the Cell (© Garland Science 2008)
Innate vs adaptive immune response
Innate immunity
Complement
Phagocyte system
Toll-like receptors (TLRs)
bacterial molecule
Highly conserved integral proteins
present in the membranes on cells of
the innate immune system
At least 12 in humans
All TLRs (with the exception of
TLR3) associate with and activate the
nuclear factor NF-κB pathway
Lead to release of cytokines and T/B
cell activation
Features of adaptive immunity
Antigenic specificity
Diversity
Immunologic memory
Self/nonself recognition
T cell activation by dendritic cell
T cell
Molecular Biology of the Cell (© Garland Science 2008)
Macrophage
T cell activation by a dendritic cell in vivo
The T cell suddenly becomes bright green as intracellular
Ca++ increases as a result of activation by the dendritic cell
Cytotoxic T cells recognize foreign peptides in association
with class I MHC proteins, whereas helper T cells and
regulatory T cells recognize foreign peptides in association
with class II MHC proteins
Molecular Biology of the Cell (© Garland Science 2008)
TH1 vs TH2 T-helpers
Differentiation of
naïve helper T cells
into either TH1 or TH2
effector helper cells in
a peripheral lymphoid
organ
Molecular Biology of the Cell (© Garland Science 2008)
Many molecules are involved in
T cell – APC interaction
Dendritic cell acting as APC
B cells can also act as APC
Cell mediated cytotoxicity
Nonsecretory lysis
Secretory lysis
ADCC (antibodydependent cellular
cytotoxicity)
Immunoglobulin G (IgG)
Molecular Biology of the Cell (© Garland Science 2008)
Genetically engineered antibodies can be
used as therapy
Immunological memory
When stimulated by their specific antigen,
naïve cells proliferate and differentiate.
Most become effector cells, which function
and then usually die, while others become
memory cells.
During a subsequent exposure to the same
antigen, the memory cells respond more
readily, rapidly, and efficiently than did the
naïve cells: they proliferate and give rise to
effector cells and to more memory cells.
Molecular Biology of the Cell (© Garland Science 2008)
Properties of some cytokines
Molecular Biology of the Cell (© Garland Science 2008)
Cytokine-based therapies in clinical use
Nobel Prizes for immunologic research