Reticuloendothelial system

lectures series in basic hematology

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2. Also known as:
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3. RES is an essential component of
the immune system.
The main organs include the liver,
spleen, lymph nodes, bone marrow,
thymus and intestinal tract
associated lymphoid tissue.
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4. Cellular components of RES
1.Monocytes.
2.MacrophageLocated in all
tissues such as skin (Langerhans
cells), liver (kupffer), spleen,
bone marrow, lymph nodes, lung.
3.Endothelial cells: bone marrow,
spleen, lymph node.
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5. Macrophages
Often remain fixedto their
organs. They filter and destroy
objects which are foreign to the
body, such as bacteria, viruses.
Some macrophages are mobile, and
they can group together to
become one big phagocyticcell in
order to ingest larger foreign
particles.
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6. Formation of
Macrophages
1.Begin by Stem cell in Bone Marrow:
-Monoblast promonocyte mature monocytes
(released into blood).
2.Stay for 10-20 hours in circulation.
3.Then leave blood to tissues transforming
into larger cells macrophage.
4.Macrophage life span is longer up to few
months in tissues.
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7. FIXED TISSUE MACROPHAGES
Known by different names in different sites.
The nameThe organ
KupffercellsLiver
Alveolar macrophagesLung
LangerhanscellsSkin
HistiocytesConnective tissue
MicrogliaCNS
OsteoclastsBone
Reticular or Dendritic
cells
Spleen/Bone
marrow/Lymph nodes
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8. Characterized by an increase in:
Cell size.
Number and complexity of
intracellular organellesGolgi,
mitochondria, lysosomes.
Intracellular digestive enzymes.
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9. FUNCTIONS OF THE RES
1.Phagocytosis: Bacterial, dead
cells, foreign particles (direct).
2.Immune function: processing
antigen and antibodies production
(indirect).
3.Formation of bile pigments.
4.Breakdownof aging RBC.
5.Storage and circulation of iron.
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10. Phagocytosis
Phagocytosisis part of the
natural or innate immune process.
Macrophages are a powerful
phagocyticcells:
Ingestup to 100 bacteria.
Ingest larger particles such as old
RBC.
Get rid of waste products.
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11. Direct anti-inflammatory
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12. Mechanism of phagocytosis
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13. Indirect Immune role Of RES
Indirect immune function of RES:
◦Ingest foreign body, process it and
present it to lymphocytes.
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14. Antigen processing
Antigen processing: degradation of
proteins into peptides that can be
presented on MHC I or MHC II
◦MHC I presents peptides derived from
cytoplasmicantigens
◦MHC II presents peptides derived from
extracellular or intravesicularantigens
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15. Antigens are derived from cytosolic
or vesicular compartments
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16. The lymphatic system is composed of:
1.Primary lymphoid organs:include the
bone marrow and the thymus. They create
special immune system cells called
lymphocytes.
2.Secondary lymphoid organs:These organs
include the lymph nodes, the spleen, the
tonsils and certain tissue in various mucous
membrane layers in the body (e.g. in the
bowel).
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17. Lymph nodes filter lymph before it is
returned to the blood
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18. Leukocyte defense cells within
lymph nodes:
◦Macrophages–engulf and destroy
foreign substances
◦Lymphocytes–provide immune response
to antigens
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19. Thymus:
◦Produces hormones (like thymosin) to
program (“educate”) certain lymphocytes
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20. Tonsils:
◦Small masses of lymphoid tissue around
the pharynx
◦Trap and remove bacteria and other
foreign materials
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21. Peyer’sPatches:
◦Found in the wall of the small intestine
◦Capture and destroy bacteria in the
intestine
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22. It is a soft purple gray in color located in the
left upper quadrant of the abdomen.
It is a highly vascular lymphoid organ.
It is the part of RES and its absence leads to
a predisposition toward certain infections.
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23. : provides
the immune functionof
the spleen.
Red pulp: surrounds
white pulp, composed
of Venous sinusesfilled
with whole blood and
Splenic cords of
reticular connective
tissue rich in
macrophages.
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24. 1.Haematopoiesis: fetal life.
2.Spleen is a main site for
destruction of RBCs specially old
and abnormal e.g. spherocytosis.
3.Blood is filteredthrough the
spleen.
4.Reservoir of thrombocytes and
immature erythrocytes.
5.Recycles of iron.
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25. 1.Because the organ is directly
connected to blood circulation, it
responds faster than other lymph
nodes to blood-borne antigens.
2.Destruction and processing of
antigens.
3.Reservoir of lymphocytes in white
pulp.
4.Site for Phagocytosisof bacteria
and worn-out blood cells.
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26. Impaired splenicfunction or
splenectomylead to:
Reduce the ability to make antibody,
particularly to capsulated organisms.
Reduces clearance of intracellular
organisms(e.g. parasitized red
cells).
Impairs defense against organisms
and toxins in the portal circulation.
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27. It is the central factory for production of
all adult hematopoietic cells.
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28. Bone marrow is a highly cellular,
viscous , and highly vascular tissue
present within the hollow cavities of
hard bone and is specially designed
to support the proliferation,
differentiation, and maturationof
hematopoietic cells .
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29. Depending on proportion of adipocytes&
hemopoieticcells.
1.RED:(rich in haemopoieticcells).
2.YELLOW:(composed of fat cells)
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30. 1.Vascular compartment
2.Hematopoietic compartment
a) Hematopoietic cells
b) Stromalcells
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31. Cells of the BM:
Erythroidseries
Myeloid series
Megakaryocytic series
Monocyticseries
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32. Cellularity
(hematopoietic/fatcell)
Site Age
100/0All bones, liver &
spleen
Newborns
70/30Most bonesChildren
50/50Axial bonesAdults
30/70Axial bonesOldage
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Marrow cellularityvary according
to age.

33. Myeloid : Erythroidratio (M:E)
The M:Eratio is the ratio of all
granulocytic plus monocyticcells
(Myeloid) to all erythroblasts
(Erythroid).
Lymphocytes, monocytesand plasma
cells are not included in the M:E ratio.
The normal ratio of 3:1 to 4:1 reflects
the relationship between production
and life span of the various cell types.
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34. Alteration in M:E ratio
NormalM:E:
Does not reflect changes, as both series
are equally affected—e.g., in aplastic
anaemia, myelosclerosis, chloramphenicol
toxicity.
DecreasedM:E:
-Haemolyticand megaloblasticanaemias.
IncreasedM:E:
-CML, leukaemoidreactions.
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