3.lecture 5- resistance of the body to infection-1428

8/11/2019 3.Lecture 5- Resistance of the Body to Infection-1428

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Blood Physiology

Professor A.M.A Abdel Gader

MD, PhD, FRCP (Lond., Edin), FRSH (London)Professor of Physiology,College of Medicine & King Khalid University Hospital

King Saud UniversityRiyadh


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Hematopoiesis


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Monocyte-macrophage systemReticulo-endothelial System


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Reticuloendothelial System-RES

Blood Monocyte Tissue macrophage

Attached (fixed) Mobile

Function is phagocytosis of: Bacteria

Viruses Dead tissues

Foriegn particles

Immune function


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RES is widespread in the body

Cells of the RES: Monocytes (blood macrophages) Mobile and fixed tissue Macrophages Specialiazed endothelial cells in bone marrow,

lymph nodes and spleen Reticularcells of lymph nodes spleen & bone

marrow.


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Cells of the RES - Distribution:

Tissue Macrophages in skin SC tissues Tisssue Macrophages of lymph nodes

Tissue macrophages in lungs Macrphages (kupffer cells) in the

liver

Macrphages in the spleen and bonemarrow


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Blood Monocyte Tissue macrophage

Attached (fixed) Mobile

Function is phagocytosis of: Bacteria

Viruses Dead tissues

Foriegn particles

Immune function


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Lecture # 5

Resistance of the Body toinfection

Immunity & Allergy

34


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Lecture # 5

Immunity-Definition Antigens

Immune Cells (b- & T- Lymphocytes)

Antibodies and B-Lymphocytes

Cellular Immunity

Clinical Application


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Immunity?

The ability of the body to resistdamage (caused by micro-organisms, toxins etc)

Immune system act to maintain health(i.e. homoestatic)

Immunological defenses act against:

foreign organisms e.g. bacteria, viruses transplanted tissue or organs


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Immunity -- Types

1. Acquired immunity:the result of attack by bacteria, viruses etc

e.g.Vaccination Long lasting (Memory)

2. Innate immunityNon-specific: Examples:

Ingestion of invading organisms (phagocytosis)

Stomach acidity Skin barrier Lysozyme Natural killer lymphocytes


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Immunity -- TypesAcquired immunity: Specific against individual bacteria, virus,

toxin, foreign tissues

Basic types of acquired immunity:

Humoral immunity

(B-cell immunity)B-LYMPHOCYTESAntibodies

Cell-mediated immunity(T-cell immunity)

Activated T-LYMPHOCYTES

Initiated by antigens


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Immunity -- Types

1. Acquired immunity2. innate immunity

Non-specific ingestion of invadingorganisms

No memory cells

Phagocytic cells Neutrophils macrophages


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Antigens


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Antigens

Antigens: Specific chemical compounds (proteins,

polysaccharides) that initiate acquiredimmunity

High mol. weight (>8000)

Antigenicity due to presence ofcharacteristic epitopes(moleculargroups) on its surface


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Antigens If mol. Wt


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The bases of

Acquired Immunity

are Lymphocytes


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Immune cells

Two types: B-Lymphocytes

(Thymus independent, B-lymphocytes)

Produce antibodies(Humoral Immunity)

2. T- lymphocytes(Thymus dependent, T-lymphocytes)Cellular mechanisms

(Cellular Immunity)

H i i


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Hemopoiesis

(17.9)


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Lymphocytescont.

LymphopoiesisStem cell

(thymus, lymphoid tissue & bone marrow)

lymphoblast

intermediate pyronophilic blast cells

lymphocytes

B L h t


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B- Lymphocytes(thymus-independents)

Found in: Bone marrow, germinal layer of

lymph node, red pulp of spleen

Life span: 2-7 days Stimulation by antigen large

plasma cell (producers of antibody)

Function: Humoral immunity.


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Lymphocytes

B lymphocytes transform into plasma cellsand secrete antibodies

(17.6b)


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Lymphocytes

T lymphocytes can attack foreign cellsdirectly

(17.6)


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h


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T-Lymphocytes(thymus dependent)

Formed in: bone marrow or lymphoid tissues

migrate to thymusLife span: 100-130 days.

Circulate between blood, tissues,

lymph.

T L h


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T-Lymphocytes(thymus dependent)

Types of T-lymphocytes T-helper

T-cytotoxic

Natural killerFunctions

Cellular immunity graft rejection

delayed hypersensitivity.

Help in antibody secretion.


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Helper T Cells

Identified byCD4coreceptor.

Indirectlyparticipate byregulating theresponse ofboth T killerand B cells.

B cells must beactivated byhelper T cellsbefore theyproduce

antibodies.


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T Cell Response to a Virus (continued)

Foreign antigens

attach toimmunoglobulins on

B cells.

B cells can present

the antigen withclass-2 MHC

molecules to helper

T cells.

Stimulate B cellproduction,

conversion to

plasma cells, and

antibody production.


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Antibodies(Immunoglobulins-Ig)


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Antibodies -(Immunoglobulins-Ig)

Antibody is a gamma globulinproducedby plasma cells(B-lymphocytes)

Subdivided into 5 classes: IgG, IgM IgD IgE

IgA. Bind specifically to the antigenagainst which they have been

produced


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Antibody

H l i it


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Humoral immunity(Acquired immunity)

B-lymphocytes surface receptorsinteract with antigen

B-lymphocytes proliferate to plasma

cells

Plasma cells secrete specific antibodyto destroy the antigen

Some of the stimulated cells do notproliferate stay dormant as

memory cells

H l i it


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Humoral immunity(Acquired immunity)

Action of AntibodyAgglutination PrecipitationNeutralization

Lysis


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Antibody Antigen complex


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Immune Responsein humoral immunity

The immune response of the body whenexposed to antigen

1. Primary immune response: first exposure to antigen

antibodies formed after a latent periodone week(time needed for multiplication

and maturation of lymphocytes) e.g. vaccination


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Immune Responsein humoral immunity

2.Secondary immune response: second exposure to the same

antigen. immediate production of high titer

antibodies

Memory lymphocytes (from firstexposure) act immediately whenexposed to the same antigen


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Immune response


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Cellular Immunity


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Cellular immunity

T-cell react with antigenby itsreceptors and proliferate to give either:

Cytotoxic (killer) T cells CD8 (Tc)

Helper T cell CD4 (Th)

Suppressor T cells (Ts)


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T helper Cell

Most numerous cells

Major regulator of immune system

Secret lymphokinese acts on othercells of immune cells Stimulate growth of other T-lymphocytes

Stimulate B-lymphocytes growth and

maturation into plasma cells Activation of macrophage system


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Cytotoxic T cells

T cell directly attack organism,foreign infected cells and destroyed it

Bind to antigen by surface receptors

making holes in it membrane Function:

Rejection of transplanted tissues (kidney)

Antitumor immunity Cooperation with B cell in humoral immunity


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Cytotoxic T cells

l l l


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Clinical application

The Acquired Immune DeficiencySyndrome (AIDS) Normal Th : Tc ratio = 2:1 AIDS virus selectively attack Th

(CD4), ratio =1:2

Generalize inhibition of immune

response

Patient prone to bacteria/ virusesinfection & Cancer


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Humoral immunityAllergy

Excess Antibody production:

hypersensitivity(allergy) Allergins: dust, pollen, drugs.

Leucocytosis


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Leucocytosis(Increased WBC Count)

Causes: Physiological

Diurnal: morning evening After physical exercise Stress or Adrenaline injection

Disease (pathological)

Bacterial infections (tonsillitis,appendicitis Worms infestations

L i


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Leucopenia(Decreased WBC Count)

Causes: Malnutrition Typhoid fever Depressed bone marrow Deficiency of Vit B12or folic acid

Leukaemia


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Leukaemia(Cancer of white cells)

Causes: chromosomal abnormality chemicals, radiation, and virusesWBC:> 50x103Types of leukaemia

Myeloblast leukaemia myeloid cells

Lymphoblast leukaemia lymphocytic cells Acute or chronic Accompanied with anaemia, bleeding


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Defence of the body against infectionsand foreign invadors

Functions of Leucocytes- WBC

Neutrophils & monocytes (Blood macrophages)-Phgaocytosist/+ Immunity

Macrophage (RES) system Phagocytosis +

Immunity

Lymphcytes.. IMMUNITY


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THANK YOU

3.lecture 5- resistance of the body to infection-1428

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