Transcript White Blood Cells (WBC`s) or Leukocytes

White Blood Cells (WBC's) or
Leukocytes
.
Classification of WBC's:
1. Granulocytes (polymorphonuclear
leukocytes): cytoplasm contains granules. This
type is the most numerous which is subdivided
into:
A.Neutrophils.

B. Eosinophils.

C.Basophiles.
2. Agranulocytes(Mononuclear leukocytes):
have agranular cytoplasm (no granules) and
subdivided into:
a.Lymphocytes.
b. Monocytes.
1. WBC count in the blood
a. Total WBC count: normally is 4000-11000 WBC/c.mm
of human blood in both male and female.
b. Differential WBC's count which indicates the
percentage (%) of each type of leukocytes in the blood:
Neutrophils: 60-70%
Eosinophils: 1- 4%
Basophiles: 0.5-1%
Monocytes: 2- 8%
Lymphocytes: 20- 40%
2. Leukopoiesis: production of WBCs.
a. Myeloblasts: from which granulocytes
(neutrophils,eosinophils and basophiles).
b. Lymphoblasts: from which lymphocytes
developed.
c. Monoblasts: from which monocyte
developed .
D.Megakaryoblast:fromwhich megakaryocytes
developed ended in the formation of platelets.
Genesis of WBCs
The granulocytes & monocytes are formed in
the bone marrow
Lymphocytes & Plasma cells are formed
partially in the bone marrow & mainly in
the lymphogenous tissues,spleen,thymus,
tonsils .
WBCs stored in the bone marrow(BM) until
needed, their number in the BM is about 3
times as many as circulating WBC in the
blood.In(BM)MYELOID:ERYTHROID ratio= 3:1
Lymphocytes are stored in the lymphoid
tissues.
Life span of the WBCs
Normally granulocytes after being released from
BM are 4-8 hours in the blood & another 4-5 days
in tissues in serious infections their life span
become shorter .
Monocytes 10 -20 hours in the blood when
become macrophages they live for
months
Lymphocytes life span is weeks to months or
years.
Platelets life span is 10 days normally .
3. Most leukocytes are mobile, exhibiting:
1- ameboid movement: Both neutrophils and macrophages can move
through tissues.
2- diapedesis : Neutrophils and macrophages squeeze through the pores
of the blood capillaries by diapedesis.
3-chemotaxis:Attraction of WBCs to inflamed tissue areas , the
chemotactic substances are
a.some of the bacterial or viral toxins .
b.degenerative products of the inflamed tissues.
c.several reaction products of the complement complex.
d.reaction products caused by plasma clotting .
4. phagocytosis depends on three selective procedures:
A-rough surface B-dead tissues have no protective prot. coats,
C- The immune system produce antibodies+Ba+C3 which attached to the
receptors on phagocyte membrane this selection and phagocytosis
process called opsonization.
Specific Functions of Different types of Leukocytes
Neutrophils:
1. the neutrophils have been called the body’s first line
of defense against bacterial infection. In patients
with bacterial infection the neutrophil count is
greatly
increased
(neutrophilia).
Lack
of
neutrophils called neutropenia.
2. Release lysosomal enzymes that kill
microorganisms.They produce superoxide,H2O2
Hydroxyl ions all are lethal to bacteria.
Myeloperoxidase catalyzes the reaction between
the H2O2 & chloride ions to form hypochlorite it is
a powerful bactericidal.
3. phagocytize microorganism and phagocytize 3-20
bacteria before it dies.
(Macrophages: phagocytizing 100 bacteria & contain
lipases that digest thick lipid membranes of some
bacteria example: (tuberculosis bacillus).
.
Monocytes: are the largest type of leukocytes.
1. Leave the circulation, enter tissues, enlarge and
transformed into macrophages which are important
in late stages of infection. 2 Produce chemicals
such
as
prostaglandins,
interferons
and
complement that are important in immune system
response. 3. Macrophages are given specific
names such as dust cells in lungs and kupffer cells
in the liver. Macrophages are present in the skin,
lymph nodes , bone marrow and spleen.
Lymphocytes:. are the smallest leukocytes.
2. Types are: T-lymphocyte. 2. B-lymphocytes
which differentiated into plasma cells that produce
antibodies or immunoglobulins (Igs). These
antibodies responsible for destroying foreign
antigens. 3. Natural killer cells.
Basophils:
1. Release chemicals such as histamine, bradykinin,serotinin &
lysosomal enzymes which promotes inflammation. Release
heparin which prevents clot formation. In allergic reactions
basophil count are elevated (basophilia) is found in basophilic
myelocytic leukaemia.
Eosinophils
1. release enzyme that inhibit inflammation caused by chemicals
such as histamine. 2. Release enzymes that kill some parasite so
in patients with parasitic infection eosinophils number greatly
increased.They release hydrolytic enzymes, reactive oxygen&
larvacidal polypeptide.
Mast Cells:
1. are heavily granulated wandering cells located at points of
entry of microorganism into the body such as skin, lungs, GIT and
urogenital tract. 2. Contain histamine which promotes
inflammation.
3. Contain heparin which prevent clot. 4. have antibody IgE on
their cell membrane.
INFLAMMATION
when tissue injury occure,by chemicals,Ba,trauma
other causes; many substances released by the
injured tissues and cause secondary changes in
the surrounding uninjured tissues this entire
changes is called inflammation.It is
characterized by: 1.Vasodilatation increase
blood flow. 2. increase permeability of the
capillaries & fluid leak into interstitial spaces.
3.clotting of fluid (presence of fibrinogen).
4.Migration of large number of granulocytes &
monocytes into tissues 5. Swelling of the tissue
cells due to secretion of :A-Histamine
B-bradykinin C- Serotonin D-prostaglandin
E- Reaction products of complements, lymphokines
released by T cells. ALL strongly activate the
macrophages.
Walling Off; Effect of
Inflammation
Results of inflammation is to wall off area of injury from
remaining tissue.the tissue space and the lymphatic are
blocked by fibrinogen.
Ex:Staphylococcus release toxic fatal substance
inflamation develop rapidly much more than their
multiplication.Streptococci reproduce & migrate
through tissue.They do not cause walling off rapidly,It
is a slow process it may cause death.
Tissue Macrophages are the first line of defence against
infection, macrophages,histiocytes in the subcutenous
tissue,alveolar macrophages in the lungs, microglia in
the brain all have phagocytic action .They are activated
by products of inflammation ,they enlarge migrate to
the site of infection.
NEUTROPHILS; are the 2nd line of defense:
Margination,diapedesis,ameboid movement,
Chemotaxis , opsonization & phagocytosis;N count
become 15000-25000 in case of infection& called
neutrophilia.
Third line of defense is the invasion of second
macrophages into the inflamed area
Along with Neutrophils,Monocytes,enter the
tissues. M are low in blood & bone marrow
compared with the number of neutrophils( N ).
When monocytes enter the tissue they need 8
hours to swell &( several days to weeks) to form
lysosomes.
The fourth line of defense is the production of the
granulocytes & monocytes by the bone marrow it
takes 4-5 days their production is stimulated by
the products of inflammation.
Feedback Control of the Macrophages and
Neutrophil Responses
Many factors affect the control of macrophage
response to inflammation five of them play an
important roles, they are:1. Tumor necrosis factor
(TNF).2.Interleukin-1(IL-1) 3. Granulocyte
monocyte colony-stimulating factor (GM-CSF).
4.Granulocyte colony-stimulating factor (G-CSF).
5.Monocyte colony-stimulating factor (M-CSF).
They stimulate the bone marrow to increase the
production of granulocytes,monocytes/macrophages.
The process begin with tissue inflamation & ended in
the formation of large number of defensive WBCs that
remove the cause of inflammation.
Formation of pus
Neutrophils & macrophages engulf bacteria &
necrotic tissue ( all neutrophils & most M )die.
A cavity is formed after several days in the
inflamed tissues contain ( necrotic tissues,
dead neutrophils , dead macrophages and
tissue fluid) this mixture called pus.
After the infection is suppressed the dead
cells and necrotic tissue after days autolyze,
The end product absorbed in to the surrounding
tissues and lymph.
Leukopenia: occurs when the bone marrow
produces very low WBCs leaving the body
unprotected against many bacteria & other agents
that might invade the tissues.Causes are
irradiation x-ray,gamma rays,exposure to drugs or
chemicals containing benzene or common
antibiotics ex. Chloramphenicol ,thiouracil and
others
Leukocytosis: is an abnormally high WBC
count. Bacterial infection causes leukocytosis.
Leukemia: a tumor of the red marrow. Leukemia
is characterized by greatly increased numbers of
abnormal WBC's in the circulating blood.