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Immune system

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AimsAims

• Lymphatic organs

• Major histocompatibility complex (MHC)

• Natural immune system

• Adaptive immune system

• Disorders of the immune system

• Inflammation

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Immune systemImmune system

Lymphoid organsLymphoid organs

Immune cellsImmune cells

Immune proteinsImmune proteins

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The immune system is a complex of organs, cells,and circulating protein

What is the immune system?What is the immune system?

Lymphoid organsLymphoid organs

thymus

spleen

Lymph node

mucosa-associated lymphoid organ (MALT)

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Immune cellsImmune cellsImmune cells

Leukocytes or White blood cells

Neutrophil Lymphocyte

Monocyte

Eosinophil Basophil

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Lymphocyte

B cells: antibody

T cells: phagocytosis

Cytotoxic T cells

Helper T cells

Suppressor T cells

NK cells

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Immune proteinsImmune proteinsImmune proteins

AntibodiesAntibodies

ComplementsComplements

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InflammationInflammationInflammation

Body’s local response to infection or injury

1. Injury or bacteria entry into tissue

2. Vasodilatation of the surrounding vessels

blood flow (hot and redness)

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4. Neutrophils and monocyte from capillaries into infected area

5. Destruction of bacteria in the tissue (pus)

6. Tissue repair

3. Filtration of protein and fluid into interstitial fluid(swelling)

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Immune systemImmune system

Natural immune system(nonspecific)

Natural immune systemNatural immune system(nonspecific)(nonspecific)

Adaptive immune system(specific)

Adaptive immune systemAdaptive immune system(specific)(specific)

- Humoral immunity

- Cell mediated immunity

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Natural immune systemNatural immune systemNatural immune system

• Innate defense mechanism

Non specific to any antigen

genetic

Surface barrier and mucosal immunitySurface barrier and mucosal immunity

• skin

• coughing, sneezing, ciliary action: lung

• sticky mucous

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• skin secretion: acid pH

• saliva, tear, nasal secretion: lysozyme

• stomach: hydrochloric acid and protein digesting enzyme

Cells of natural immune are:Cells of natural immune are:Cells of natural immune are:

• phagocytes

• natural killer cells(NK cells)

• mast cells

• eosinophil

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phagocytesphagocytesphagocytes• neutrophil

• macrophages:spleen

medullary sinus of lymph node

Liver: kuffer’s cell

monocytesmonocytes

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Natural killerNatural killer

• Large granule lymphocyte

• precise mechanism by which they recognized

their target cells is not clear

• Target cells: tumor cell or virus-infected body

cells

• kill on contact

• can be stimulated by interferon 16

Natural killerNatural killer

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EosinophilEosinophil

• granule contain a protein rich in arginine residues

calledcalled major basic proteinmajor basic protein

• The least numerous of WBC in blood

•• Cell can secrete membrane penetrating protein Cell can secrete membrane penetrating protein

called called perforinsperforins

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•• Important in killing Important in killing helminthhelminth (worm) infections(worm) infections

•• Involve in hypersensitive reactionInvolve in hypersensitive reaction

•• cell cancell can releaserelease killing enzyme called killing enzyme called peroxidaseperoxidase and and

PhospholipasePhospholipase DD

EosinophilEosinophil

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ComplementComplement

•• A major trigger enzyme plasma systemA major trigger enzyme plasma system

•• Important in killing bacteria and fungiImportant in killing bacteria and fungi

PhagocytosisPhagocytosis

Making pore in bacterial cell membraneMaking pore in bacterial cell membrane

Help to get rid of AgHelp to get rid of Ag--AbAb complexcomplex

•• Important in Important in initiaioninitiaion of the inflammatory responseof the inflammatory response20

ComplementComplement

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Adaptive immune systemAdaptive immune systemAdaptive immune system

• acquired immunity

• Specific and memory

Humoral immunity Cell mediated immunity

B lymphocytes and antibodies

T lymphocytes

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How antigen meet T& B lymphocyte

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Adaptive immune systemAdaptive immune systemAdaptive immune systemPathogens Humoral immunity

Cellular immunity

B cell

Antibodies

T cell

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Humoral immunity

B lymphocytes

•• produce from bone marrow and thymusproduce from bone marrow and thymus

•• can transform to can transform to plasma cell plasma cell by antigensby antigens

B cell

Plasma cell Antibodies

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Antibodies

•• ImmnunoglobulinImmnunoglobulin

•• Y shape: heavy and light polypeptide chainsY shape: heavy and light polypeptide chains

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•• There are 5 main classes: There are 5 main classes: IgGIgG, , IgAIgA, , IgMIgM, , IgDIgD, , IgEIgE

•• IgGIgG

Most abundantMost abundant

cross from mother to baby and protect baby cross from mother to baby and protect baby

for 2for 2--3 months3 months

•• IgAIgA

common in secretion common in secretion egeg saliva, gastric juicesaliva, gastric juice

found in milk found in milk

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•• IgMIgM

primary immune response primary immune response

activate complement activate complement •• IgDIgD

act as surface receptor on B cells act as surface receptor on B cells

•• IgEIgE

bound to mast cells bound to mast cells

involve in pathogenesis of allergic and involve in pathogenesis of allergic and helminthhelminth

disease disease 28

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• human makes 10,000,000 different kinds of antibodiestoo much for genome to encode

Antibody diversity

• Clonal selection

• Each B cell makes 1 kind of antibody

• Each antibody composed of identical light and identical heavy chains

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ClonalClonal selection selection

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Cell mediated immunityCell mediated immunityT cell

Originate in thymus of infants

Produced in bone marrow of adults

T cell function

Do not secrete antibodies

Some attack other cells (T cytotoxic; TC)

Some produce lymphokines -- molecules that regulate other white blood cell responses

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Self and non-selfSelf and nonSelf and non--selfselfHow immune system recognize body cell?

Specific recognition molecules: Major

histocompatibilty complex (MHC)

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MHC (HLA)MHC (HLA)• Set of molecule making up tissue type

• There are three types of MHC

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- MHC III : complement

- MHC I : present endogenously synthesized antigen

- MHC II : present exogenously derived protein eg bacterial products

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MHC MHC mechanismmechanism

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How immunity is not destroy themselves

ThymusThymus

T & B lymphocyte that react to body cellsT & B lymphocyte that react to body cells

Will be destroyedWill be destroyed

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Disorders of the immune systemDisorders of the immune system

Graft Rejection

- MHC on the graft cell differ from MHC of

recipient.

- Cytotoxic T cells are mainly responsible for

graft rejection.

- Immunosuppressive drug prevent graft

rejection. 38

Donor APCDonor APC Recipient APCRecipient APC

Recipient T cellRecipient T cellRecipient T cellRecipient T cell

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Transfusion reaction

- ABO is the most important for transfusion

reactions.

- ABO blood group mismatch results in

hemolysis. 40

Acquired immune deficiency syndrome (AIDS)

- Human immunodeficiency virus (HIV) is a

retrovirus.

- Integrated the

virus RNA into

Host DNA.

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- HIV enter and live in helper T cell.

- infected T cells are destroyed by normal T

cells, therefore T cell reduce in amount.

- Immune defense of host can not function

properly.

- AIDS patient dies from infections or

cancers.42

Allergy

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Autoimmune disease

- Immune attack the body’s own cells and

tissues which results is being damage

and/or alteration function of organs

Multiple sclerosis – myelin

Myasthenia gravis – acetylcholine receptor on

skeletal muscle

Grave’s disease – Thyroid stimulating hormone

receptor

For examples

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Autoantibody to Autoantibody to receptorreceptor