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Immunology

Lecture ( 7 )

Dr, Baha,Hamdi,AL-Amedi Ph. D.Microbiology

HOST DEFENSE

The Origin of Immune Concept-I

–The term “Immunity-1”

Latin word “Immunitas”

:Protection from legal prosecution

Biological definition: Protection from infectious diseases

Edward Jenner (1796)

The scientific view of immunity = Edward Jenner (1796)

Observation Milkmaids generally get No smallpox

Hypothesis = Pus from vaccinia (cowpox)

Protect milkmaids from smallpox

The Origin of Immune Concept-II

The concept of “Immunity” developed

gradually through many scientific findings:

Robert Koch (1905 Nobel Laureate) :Infectious

diseases caused by microorganisms

Louis Pasteur :Vaccines against cholera & rabies

These clinical successes = The search of underlying mechanism of “Protection of Infectious Diseases”

The development of “Immunology”

Advances in technology (e.g. Cell culture, Monoclonal Ab, Flow cytometry, Genetic engineering…etc) have facilitated our understanding of the immune system and its

Non-specific defense mechanism

:

It is an inherent resistant present in the host body they are present as normal components they are not induce by exposure to infection .

There are different determinants affected

this immunity.

A- host determinant.

1-Age

2-hormones &nutritional

3-Genetic back ground(Hereditary factors)

B-physical determinate

: as membrane barrier ,moist surface .

Skine; it is first line of defense against infection consisting

keratinized outer layer

also secretion of sweat ,sebaceous, fatty acid , tears.

C-Active antimicrobial

determinant:

Mucus:it is coats the epithelial cell of mucosa which trapped microbes and remove it with different mechanism:

1-cilia in respiratory tract

2-coughing & sneezing in respiratoy tract

3- flashing reaction of saliva , tears

C-Active antimicrobial

determinant:

Antibacterial &Antifungal secretion of skin. Sweat & sebaceous secretion

.

Antibacterial &Antiviral secretion of mucus membranes.

Phagocytosis& digestion.

Antimicrobial substances of tissue fluids, e.g lysozyme, basic polypeptides

Phagocytosis& digestion.

Macrophage:it is either monocytes or

Polymorphnuclear leukcytes (PMN)

Which are present in peripheral blood or in tissue.

The main function is phagocytosis to ingestion & destroy invades microbes

There are variety of molecules which react with many microbes ;

1-Acute phas protein

2-Complement

3 Cytokine

Interferon :

The important of cytokine in Non-specific immunity is Interferon(INF)

Interferon :It is family of cytokines produced by a wide varity of cell such as fibroblast macrophage & epithelial cell they induce by viruses and produced

Interferon :

Innate immunity

First line of defense

–Penetration of the epithelial surface of the body by microorganism (e.g. bacteria)

– Engulfment of microorganism by macrophages, neutrophils, and dendritic cells

–Release of cytokines and chemokines

–Inflammation

Inflammation

Adaptive (acquired) immunity

–Takes time to develop

Humoral immunity (antibody–mediated

specific immunity)

Cell-mediated immunity (The aspect of the adaptive immune response where antigen-specific T cell have a main role)

Antigen:

it is a substance that cause immune response when it introduce into the body of the host , the Antigen have the following character:

1- Have large molecular weight about 10.000 Dalton or more

2-It should have large surface area .

3-It should specificity:this spcificity due to antigenic

determinantion (epitopes): which is surface located with certain

sequence in sterochemical structure of substance.

4-Chemical complexity :Antigen should have a great degree of complexity ,protein are the

most potent immunogen because of the three dimention of its structure

5-Foreigennes: Antigen must be foreign to the host which it makes contact with it,so it should be recogonized when interoduce into the human

or experimental animales

Immunogen: it is any substance forigen to

host of immune system therefor any microorganism get into the body host and it is forigen into the body host so it is recogonized

by cells of immune system and induce the immune response .

one must differentiate between antigen which is

react(in vitro) with the products of immune system and immunogen which is induce the immune response lead to the production of antibody or T-lymphocyte.

Hapten: substance with multi determinants as Allargen molecul can not initiate immune response but react with the product of immune response e.g drugs may adsorbs on surface of

R.B.C . stimulating this will result in hemolytic

disease and lysis of R.B.C

Hapten:

Immunological Adjuvant: substance are add to vaccine or antigen to stimulate & enhance theimmune response, Inorganic gell, Alamin salt it the sole adjuvant acceptable for human vaccine.

The end