Basic ImmunologyBasic Immunology

University of Tabuk

Faculty of Applied Medical Science

Department of Medical Laboratory Technology

Mr.AYMAN.S.YOUSIFMSc.Medical Microbiology

& Immunology

Academic Year: 1433-1434 (2012-2013)

Mr.AYMAN.S.YOUSIF 11-12/02/2013

Lecture 2

Arms of Immune SystemArms of Immune System

Innate Immunity

Objectives

At the end of this lecture, you should be able to:

1. Recognize the significance of the immune system in combating infection and disease.

2. know the humoral and cellular components of innate immunity.

3. Understanding the mechanism of action of the humoral and cellular components of innate immunity.

4. Understanding the major Function of innate immunity .

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Arms of the Immune SystemArms of the Immune System2

Innate (Non specific) Immune System

Also called natural or native immunity.

It is present at birth; provides the early (first) lines of defense against microbes.

Consists of barriers (defense mechanisms) that are in place even before infection and poised (ready) to respond rapidly to infections. but do not adapt to a particular pathogen (non-specific).

They respond in essentially the same way to repeated infections. (no have memory ).

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Antigen recognition by Innate Immunity components

Several components of innate arm recognize what is foreign by

Detecting Certain CHO or lipid on the surface microorganism that are different from those on human cells . Component of the innate arm have receptor called

Pattern-recognition receptor that recognize a molecular pattern on the surface of microbe that

is not present on human cells. This receptors are called Toll-Like Receptor (1-10) .

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Remember

It is important to remember that infection with an organism does not necessarily mean diseases, due

to the immune system in most cases will be able to eliminate the infection before disease occurs.

Disease occurs only when

The bolus (dose) of infection is high. when the virulence of the invading organism is great .

when immunity is compromised.(Immunecomprmised).

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Important Components of Innate Immunity

1. Factors that Limit Entry of Microorganisms Into The Body.

A. Anatomical Barriers To Infections. Mechanical Factors (Barrier) . Chemical Factors (Barrier) . Biological Factors (Barrier) .

2. Factors that Limit growth of Microorganisms Into The Body.

B. Humoral Barriers To Infection. (Humoral components)

C. Cellular Barriers To Infection (cellular components )

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Barriers Factor Mode Of Action

Physical Epithelial surfaces 1. Very impermeable to most Infectious agents.

Mechanical

Keratin layer of intact skin 1. Acts as mechanical barrier.

Respiratory cilia 1. Elevate mucus containing trapped organisms.

The flushing action of tears and saliva 1. Helps prevent infection of the eyes and mouth.

Chemical

Fatty acids in sweat 1. Inhibit the growth of bacteria.

Lysozyme in tears and other secretions ( saliva & nasal secretion)

1. Breakdown the cell wall of bacteria.2. Destabilize bacterial membranes.

The low pH of sweat and gastric secretions and vagina.

1. Prevents growth of bacteria

Surface phagocytes (e.g.. alveolar macrophages)

1. Ingest and destroy microbes.

Defensins (cationic peptides) 1. Create pores in microbial membrane

Biological

The normal flora of the skin , throat, colon ,vagina ,and in the gastrointestinal tract

• Prevent the colonization of pathogenic bacteria by

1. Secreting toxic substances.2. Competing with pathogenic bacteria for

nutrients.3. Attachment to cell surfaces receptor .

A. Anatomical Barriers to Infections.8

B. Humoral barriers to infection

The Anatomical barriers are very effective in preventing colonization of tissues by microorganisms.

when there is damage to tissues, The anatomical barriers are breached and infection is occurs.

Once infectious agents have penetrated tissues, another innate defense mechanism comes into play, namely Acute Inflammation.

Humoral factors play an important role in inflammation, which is characterized by edema and the recruitment of phagocyte cells.

These humoral factors (Soluble factors) are found in serum or they are formed at the site of infection.

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Inflammation10

Humoral Factor Mode Of Action

Complement system(proteins)

1. Increased vascular permeability.2. Recruitment of phagocytic cells.3. Lysis and opsonization of bacteria.

Coagulation system 1. Increase vascular permeability .2. Act as chemotactic agents for phagocytic cells.2. Directly antimicrobial(platelets).

Lactoferrin & transferrin (proteins)

1. Limit bacterial growth. By binding iron, an essential nutrient for bacteria.

Interferons (proteins) 1. Limit virus replication in cells.

Lysozyme 1. Breaks down the cell wall of bacteria.

Interleukin-1 -11 1. Induces fever and the production of acute phase proteins,2. Opsonin (some of which are antimicrobial because they

can opsonize bacteria)

Fever 1. Elevated temperature retards bacterial growth.

Informatory response 1. Limits spread of microbes

B. Humoral Barriers to Infection.11

Innate immunity largely involves granulocytes and macrophages (although macrophages can influence adaptive immunity)

other cells are regulatory or involved with both adaptive and innate immunity and/or are precursors of another cell type

Adaptive immunity is mediated primarily by B and T lymphocytes

progenitors

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Cell Characteristics of cell & Mode Of Action

Neutrophils(PMN)

1. PMNs are the first cells to arrive at a site of inflammation.2. They phagocytose invading organisms and kill them

intracellularly.3. cells die once antigen is removed.4. Contribute to direct tissue damage that occurs during

inflammation.

1. Macrophages (Tissue macrophages) 2. Dendritic cells .3. Monocytes (newly recruited )

1. Phagocytosis and intracellular killing of microorganisms.2. Are capable of extracellular killing of infected or altered self

target cells.3. Contribute to tissue repair and act as antigen presenting cells.4. Induction of specific immune responses.

1. Natural killer cell (NK)2. Lymphokine Activated killer (LAK) cells.

1. Nonspecifically kill virus infected and tumor cells.2. Are not part of the inflammatory response.3. Are important in nonspecific immunity to viral infections and

tumor surveillance.

Eosinophils 1. Have proteins in granules that are effective in killing certain parasites.

C. Cellular barriers to infection12

Leukocytes = White Blood Cells13

Phagocytic Leukocytes14

PMNs

Polymorphonuclear Neutrophilic Leukocytes, a.k.a., PMNs. They are shorter lived than macrophages but have greater killing power.

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Non-Phagocytic Granulocytes

Eosinophils are involved in allergic responses, inflammation, and release of Histamine; Histamine is released by Basophils.

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Function of Innate Immune System

The Innate arm of our host defenses perform tow major Function .

Killing Invading Microbe . Activate Acquired (Adaptive) immune processes

e.g. Neutrophil only kill microbe .

Macrophage (MQ) & Dendritic cell(DC)

Kill microbe and present Ag to Components of Acquired immunity specially Helper T cells (CD4) Which activate

Acquired immunity

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Activate Acquired (Adaptive) immune processes

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Thank You