Monocytes are a type of white blood cell that make up 2-6% of circulating white blood cells. They exit the bloodstream through diapedesis to become tissue macrophages. As macrophages, they are phagocytic and help defend the body against viruses and bacteria.

1. 4. MONOCYTES
* Exit blood (diapedesis)
to become macrophages
* 2-6 % of the WBC's
* Phagocytic = defend against
viruses and bacteria

2. Life span of WBCLife span of WBC
 The life of granulocytes is normally 4 to 8 hoursThe life of granulocytes is normally 4 to 8 hours
in the blood and another 4 – 5 days in tissuein the blood and another 4 – 5 days in tissue
where they neededwhere they needed
 The monocytes 10 – 20 hours in the blood andThe monocytes 10 – 20 hours in the blood and
in the tissues they become larger size andin the tissues they become larger size and
become tissue macrophagebecome tissue macrophage
 Lymphocytes have life span weeks or monthsLymphocytes have life span weeks or months
depends on the needsdepends on the needs

3. LeukocyteLeukocyte
 Leukocyte (WBC) are the mobile units of the bodyLeukocyte (WBC) are the mobile units of the body
protective systemprotective system
 They are formed in the bone marrow (granulocytes andThey are formed in the bone marrow (granulocytes and
monocytes and few lymphocytes) and in the lymphmonocytes and few lymphocytes) and in the lymph
tissue (lymphocytes)tissue (lymphocytes)
 Leukocytes work in two ways to prevent diseaseLeukocytes work in two ways to prevent disease
1.1. Destroying invading bacteria/viruses by phagocytosisDestroying invading bacteria/viruses by phagocytosis
2.2. By forming antibodiesBy forming antibodies

4.  Five types of WBCFive types of WBC
 Three types of the cells are polymorphonuclearThree types of the cells are polymorphonuclear
cells. All have granular appearancecells. All have granular appearance
 The granulocyte and monocytes protect theThe granulocyte and monocytes protect the
body against invading organism by phagocytosisbody against invading organism by phagocytosis
LeukocyteLeukocyte

5.  Human being has about 7000 WBC /micro literHuman being has about 7000 WBC /micro liter
 Normal percentage areNormal percentage are
NeutrophilsNeutrophils 62%62%
EosinphilsEosinphils 2.3%2.3%
BasophilsBasophils 0.4%0.4%
MonocytesMonocytes 5.3%5.3%
LymphocytesLymphocytes 30%30%
LeukocyteLeukocyte

6.  Neutrophils and Monocytes (macrophages)Neutrophils and Monocytes (macrophages)
attack the invading bacteria, virusesattack the invading bacteria, viruses
 WBC can squeeze through the blood capillariesWBC can squeeze through the blood capillaries
byby diapedesisdiapedesis
 WBC can move by ameboid motionWBC can move by ameboid motion
 WBC are attracted to inflamed tissue area byWBC are attracted to inflamed tissue area by
ChemotaxisChemotaxis
LeukocyteLeukocyte

7.  Phagocytosis which means cellular ingestion of thePhagocytosis which means cellular ingestion of the
offending agentoffending agent
 Macrophages are much more powerful phagocytes thanMacrophages are much more powerful phagocytes than
neutrophilsneutrophils
 Lysosome in the neutrophil and macrophage come inLysosome in the neutrophil and macrophage come in
contact with the phagocytic vesicle and digestion ofcontact with the phagocytic vesicle and digestion of
phagocytized particles beginphagocytized particles begin
 Both neutrophils and macrophages contain proteolyticBoth neutrophils and macrophages contain proteolytic
enzyme. The lysosome in the macrophages containenzyme. The lysosome in the macrophages contain
lipaseslipases
LeukocyteLeukocyte

8. Neutrophils and macrophagesNeutrophils and macrophages
kill bacteriakill bacteria
 Neutrophils and macrophages containsNeutrophils and macrophages contains oxidizingoxidizing
agentagent such as Hsuch as H22OO22 which is lethal to mostwhich is lethal to most
bacteriabacteria

9. Monocyte-Macrophage CellMonocyte-Macrophage Cell
SystemSystem
 The combination of monocytes, mobileThe combination of monocytes, mobile
macrophages, fixed tissue macrophages andmacrophages, fixed tissue macrophages and
specialized endothelial cells in the bone marrow,specialized endothelial cells in the bone marrow,
spleen and lymph nodes is called Monocyte-spleen and lymph nodes is called Monocyte-
Macrophage cell system orMacrophage cell system or reticuloendothelialreticuloendothelial
systemsystem

10. Tissue macrophage in the skinTissue macrophage in the skin
 Once the skin broken, infection occur andOnce the skin broken, infection occur and
inflammation ensuesinflammation ensues
 Macrophages in subcutaneous tissueMacrophages in subcutaneous tissue
(Histiocyte) destroy the infectious agent by(Histiocyte) destroy the infectious agent by
performing phagocytosisperforming phagocytosis

11. Macrophages in the lymph nodesMacrophages in the lymph nodes
 Large numbers of macrophages line the lymphLarge numbers of macrophages line the lymph
sinuses and if any particles enter the sinuses thesinuses and if any particles enter the sinuses the
macrophages phagocytize themmacrophages phagocytize them

12. Alveolar macrophages in theAlveolar macrophages in the
lungslungs
 Invading organisms enter the body through theInvading organisms enter the body through the
lungslungs
 Tissue macrophages are present as integralTissue macrophages are present as integral
components of alveolar wallscomponents of alveolar walls
 They can phagocytize particles that entrapped inThey can phagocytize particles that entrapped in
the alveolithe alveoli

13. Macrophages Kupffer cells in the liverMacrophages Kupffer cells in the liver
sinusoidssinusoids
 Bacteria invading the body from ingested foodBacteria invading the body from ingested food
through gastrointestinal tract into the portal bloodthrough gastrointestinal tract into the portal blood
 Blood passes through sinusoids of the liver whichBlood passes through sinusoids of the liver which
lined with tissue macrophages called Kupffer cellslined with tissue macrophages called Kupffer cells
 These cells form such an effective particulateThese cells form such an effective particulate
filtration to prevent passing bacteria from thefiltration to prevent passing bacteria from the
gastrointestinal tract to the blood circulation systemgastrointestinal tract to the blood circulation system

14. Macrophages of the spleen andMacrophages of the spleen and
bone marrowbone marrow
 Macrophages of the spleen and bone marrow isMacrophages of the spleen and bone marrow is
another defense against organism that succeededanother defense against organism that succeeded
to enter the blood circulationto enter the blood circulation

15.  Inflammation is the body response to infectionInflammation is the body response to infection
or injury. The functions of inflammation are toor injury. The functions of inflammation are to
destroy or inactivate foreign invaders and to setdestroy or inactivate foreign invaders and to set
stage for tissue repairstage for tissue repair
InflammationInflammation

16. InflammationInflammation
1.1. Vasodilation of the blood vessels with consequent excess bloodVasodilation of the blood vessels with consequent excess blood
flowflow
2.2. Increased permeability of the capillaries allowing leakage ofIncreased permeability of the capillaries allowing leakage of
large quantity of fluidlarge quantity of fluid
3.3. Often clotting of the fluidOften clotting of the fluid
4.4. Migration of large numbers of granulocytes and monocytes intoMigration of large numbers of granulocytes and monocytes into
the tissuethe tissue
5.5. Swelling of the tissue cellsSwelling of the tissue cells
 Some products that cause these reaction are histamine,Some products that cause these reaction are histamine,
serotonin and prostaglandinsserotonin and prostaglandins

17.  The first result of inflammation is to “wall-off”The first result of inflammation is to “wall-off”
the area of injury from the remaining tissue.the area of injury from the remaining tissue.
 The intensity of the inflammatory process isThe intensity of the inflammatory process is
proportional to the degreeproportional to the degree
Staphylococci release lethal toxins InflammationStaphylococci release lethal toxins Inflammation
Rapid Wall OffRapid Wall Off
Streptococci no tissue destruction InflammationStreptococci no tissue destruction Inflammation
Slow Wall OffSlow Wall Off
Effect of inflammation “walling-Effect of inflammation “walling-
off”off”

18.  Within few minutes after inflammation begins,Within few minutes after inflammation begins,
tissue macrophages begins their phagocytictissue macrophages begins their phagocytic
action.action.
 Many fixed tissue macrophages break loose fromMany fixed tissue macrophages break loose from
their attachment forming the first line of defensetheir attachment forming the first line of defense
against infectionagainst infection
Macrophage and NeutrophilMacrophage and Neutrophil
Responses During InflammationResponses During Inflammation

19.  Neutrophil invasion of the inflamed area is the second lineNeutrophil invasion of the inflamed area is the second line
of defenseof defense
 Neutrophils begins to invade the inflamed area from theNeutrophils begins to invade the inflamed area from the
bloodblood
 This is caused by products from the inflamed area whichThis is caused by products from the inflamed area which
initiate the following reactions:initiate the following reactions:
1.1. Alter the inside surface of the capillary causing neutrophilsAlter the inside surface of the capillary causing neutrophils
stick on the capillary walls. This calledstick on the capillary walls. This called marginationmargination
2.2. Caused intracellular attachment to loosenCaused intracellular attachment to loosen diapedesisdiapedesis
3.3. Other product causedOther product caused chemotaxischemotaxis
Macrophage and NeutrophilMacrophage and Neutrophil
Responses During InflammationResponses During Inflammation

20.  Second macrophages invasion is a third line ofSecond macrophages invasion is a third line of
defensedefense
 Monocyte from the blood enter the inflamedMonocyte from the blood enter the inflamed
tissues and enlarged to become macrophagestissues and enlarged to become macrophages
 Macrophages can phagocytize more bacteriaMacrophages can phagocytize more bacteria
larger particles than neutrophilslarger particles than neutrophils
Macrophage and NeutrophilMacrophage and Neutrophil
Responses During InflammationResponses During Inflammation

21.  Increased production of granulocytes andIncreased production of granulocytes and
monocytes by bone marrow is the fourth line ofmonocytes by bone marrow is the fourth line of
defensedefense
Macrophage and NeutrophilMacrophage and Neutrophil
Responses During InflammationResponses During Inflammation