06. White Blood Cells

8/17/2019 06. White Blood Cells

1/18

1

White Blood Cells

(Leukocytes)


2/18

2

White Blood Cells (Leukocytes)

• Leukocytes (White blood cells or WBCs) are

the mobile units of the body’s immune defense

system

• Immunity is the body’s ability to resist or

eliminate potentially harmful foreign materials

or abnormal cells


3/18

!

"he #unction of WBCs

• "he leukocytes and their deri$ati$es

1 %efend against in$asion by pathogens

(disease & causing micro'organisms such

as bacteria and $iruses) by phagocytiing

the foreigners or causing their destruction

by more subtle means

2 dentify and destroy cancer cells thatarise *ithin the body


4/18

+

! #unction as a ,cleanup cre*- that

remo$es the body’s ,litter- by

phagocytiing debris resulting from dead

or in.ured cells

• "he latter is essential for *ound healing

and tissue rapair


5/18

/

"here are fi$e types of leukocytes

• Leukocytes lack hemoglobin (in contrast to

erythrocytes) so they are colorless that is0

,*hite- unless specifically stained for

microscopic $isibility • "here are fi$e different types of circulating

leukocytes0 "he fi$e types of leukocytes fall

into t*o main categories


6/18

& %epending on the appearance of their nuclei

& "he presence or absence of granules in theircytoplasm *hen $ie*ed microscopically

(#igure !)

& eutrophils0 eosinophils0 and basophils are

categoried as polymorphonuclear (,manyshaped nucleus-) granulocytes (3granule

containing cells-)

& "heir nuclei are segmented into se$eral lobesof $arying shapes0 and their cytoplasm

contains an abundance of membrane

enclosed granules


7/18

4

• "he three types of granulocytes are

distinguished or the basis of the $arying affinity

of their granules for dyes5

& 6osinophils ha$e an affinity for the red dye

eosin0

& Basophils preferentially take up a basic bluedye

& eutrophils are neutral0 sho*ing no dye

preference


8/18

7

• 8onocytes and lymphocytes are kno*n as

mononuclear (,single nucleus-) agranulocytes

(3cells lacking granules-)

& Monocytes are the larger of the t*o and ha$e

an o$al or kidney shaped nucleus & Lymphocytes, the smallest of the leukocytes0

characteristically ha$e a large spherical

nucleus that occupies most of the cell


9/18

9

Figure 3. Normal blood cellular elements


10/18

1:

Figure


11/18

11

!"#N$L%&%I'I

• ;ranulopoiesis (or granulocytopoiesis) is

hematopoiesis of granulocytes "he blood

granulocytes and monocytes are formed in

the bone marro* from a common precursorcell (figure /)


12/18

12Figure


13/18

1!

Control o* granulopoiesis+ myeloid gro,th

*actors

• "he granulocytes series arises from bone

marro* progenitor cells *hich are increasingly

specialied

& 8any gro*th factors are in$ol$ed in thismaturation process including interleukin'1 (L'

1)0 L'!0 L'/ (for eosinophils)0 L'0 L'110

granulocyte macrophag colony'stimulating

factor (;8'C


14/18

1+

-he *unction o* granulocytes

1 Chemota=is (Cell mobiliation and migration)

• "he phagocyte is attracted to bacteria or the

site of inflammation

• by chemotactic substances released fromdamaged tissues

• by complement components also

• by the interaction of leukocyte adhesionmolecules *ith ligands on the damaged

tissues


15/18

1/

2 >hagocytosis

• ?ecognition of a foreign particle is aided by

opsoniation *ith immunoglobulin orcomplement (both neutrophils andmonocytes ha$e #c and C!b receptors)

! @illing and digestion

A=ygen'dependent and o=ygen'independentpath*ays

n the o=ygen'dependent reactions5

•


16/18

1

& n neutrophilsm

• 2A2 reacts *ith myelopero=idase to killbacteria

• Dcti$ated o=ygen may also be in$ol$es a

fall in p *ithin phagocytic $acuoles into

*hich lysosomal anymes are released

• Lactoferrin & an iron binding protein present

in neutrophil granules & is bacteriostatic by

depri$ing bacteria of iron


17/18

14

& n the o=ygen'independent

• Dlthough more than t*o doen factors

ha$e been implicated in control of themacrophages response to inflammation0

fi$e of these are belie$ed to play dominant

roles

• "hey are consist of 5

1. tumor necrosis factor ("#)0

2. interleukin-1 (IL-1),

3. granulocyte-monocyte colony stimulating factor(;8'C


18/18

17

• "hese factors are formed by acti$ated

macrophage cells in the inflametd tissues and

• n smaller Euantities by other inflamed tissue

cells

Date post:	06-Jul-2018
Category:	Documents
Upload:	peanadss
View:	221 times
Download:	0 times

06. White Blood Cells

Documents