Overview of Immune Response 11

8/3/2019 Overview of Immune Response 11

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After working through this lecture, you should be able to:

Explain in general term the function of the immune system.

List the components of the 2 principal types of immunity;innate/natural/non-specific immunity andadaptive/acquired/non-specific immunity.

Differentiate the characteristic features of the 2 principaltypes of immune responses.


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IMMUNE SYSTEM

The Immune System is a multi-component defense andsurveillance system whose function is to recognize selffrom non-selfand to defend the body against non-self=> immunesurveillance

The immune system must be able to differentiate

between material that is a normal component of thebody (self) and material that is not native to the bodynon-self

A highly specialized receptors present for discriminatingbetween self and non-self body components


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The discrimination between self and non-self and thesubsequent destruction and removal of foreign material

is accomplished by the two arms of the immune system

1) The innate (natural or non-specific) immune system

2) The adaptive (acquired or specific) immune system

*These two systems perform many of their functions bycooperative interactions


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ORGANIZATION OF IMMUNESYSTEM

Innate/Natural

Immunity

Specific/ AcquiredImmunity

Humoral(antibody)

Cellular(cell-mediated)


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Components that contribute to

natural immunity

Anatomical barriers

epithelium: skin, respiratory and

gastrointestinal tracts

Physiological barrierscough reflex, sneezing, flushing of

urine

Chemical barriers

interferons, transferin,

complement

Phagocytosis & inflammatory

response

INNATE/NATURALIMMUNITY


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Non-inflammatory Response

Role of external body surfaces

Skin

- consists of sheets of dry, cornified , epithelial cells

- intact skin acts as barrier to bacteria and viruses

Hair follicles and sebaceous glands

- produce antibacterial substances (fatty acids and

enzymes)

Normal microbial flora

- compete with potential pathogens


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Non-inflammatory Response

Role of internal body surfaces

Normal movement of fluids and mucous

- acts as mechanical factors for cleaning internalsurfaces of Respiratory tract, Gastrointestinal

tract, Genitourinary tract


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Response of Innate Immune System

is the first line of defense

is active at the time of infection

is divided into two stages:

1. non-inflammatory reaction (bodys static defenses)

skin, gastric pH, lysozyme in tears, saliva, mucous

2. local inflammation (promotes migration of phagocytes

and plasma protein into infected tissues)

- phagocytes respond to surface structures present

in large groups of microorganisms


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Inflammatory Reaction

Inflammation is a nonspecific response of living tissueto localize and eliminate the injurious agent

Injury may be physical, chemical or biological

In inflammatory response, specialized cells and serum

proteins move from plasma to interstitial spaces to

provide an immediate defense


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Immune Cells (Microscopic)


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ACQUIRED/SPECIFIC IMMUNITY

The acquired immune response is morespecialized thaninnate immune response

The acquired immune response involves a combination

of two mechanisms :1. Humoral immune response

2. Cell mediated immune response

They interact with one another to destroy foreign body(microorganisms, infected cells, tumor cells)


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ACQUIRED/SPECIFIC IMMUNITY

Characteristic features:

Highly specific for the invading organism

Stimulated by exposure to foreign microbes

It can respond to millions of different antigens

Enhances / amplifies the mechanisms of innate

immunity


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ACQUIRED/SPECIFIC IMMUNITY (cont)

Provides the best defense against persistent or

recurrent microbial infections

Adapts to respond to individual microbes in specialized

ways using the mechanisms of humoral (antibodymediated) or cell-mediated response

Can be actively or passively acquired


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ImmunityInnate immunity Adaptive immunity

Humoral Cell-mediated

Components Components

Macrophages antigen presenting cells

Granulocytes T-cells

Natural killer cells B-cells

Complement Antibodies

Other chemicals: HCL, lysozyme Complement

Characteristics Characteristics* Action is immediate * Action requires days to develop

* Response is non-specific * Response is specific

* Response is not enhanced on * Response is enhanced on (memory)

repeated exposure to pathogen

(no memory)


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TOPICS

Immunecells Antigen

Antibody

ComplementHLA

IMMUNE RESPONSE

Immunity Immune Diseases

Immunodeficiency Hypersensitivity

Autoimmunity

Ag-Ab

Reactions

Cytokines


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References

Stites DP, Terr Al and Parslow TG. Medical Immunology. 10th Edition,

Appleton & Lange, Prentice-hall International Inc. 2001.

Roitt I, Brostoff J and Male D. Immunology. 6th Edition, Gower Medical

Publishing, London. 2001

Geo.F.Brooks, Janet S.Butel and Stephen A.Morse. Jawetz, Melnick, &

Adelbergs Medical Microbiology. 23rd Edition, McGraw-Hill. 2004.

Cedric Mims, Hazel M. Dockrell, Richard V.Goering, Ivan Roitt, Derek

Wakelin and Mark Zuckerman. Medical Microbiology. 3rd Edition, Elsevier

Mosby. 2004.

Marjorie Kelly Cowan and Kathleen Park Talaro. Microbiology A Systems

Approach. McGraw-Hill. 2006.

Overview of Immune Response 11

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