immuniology host defence

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Immunology Lecture ( 6 )
Dr.Baha,Hamdie . AL-Amiedie
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
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 fun
ctions.
n0n-specific host defences mechaisumes:
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 determinnate:
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 , tea
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 ;3-It should specificity:this spcificity due to antigenic determinantion (epitopes): which is surface located with certain sequence in sterochemical structure of substance.

1-Acute phas protein
2-Complement
3 Cytokine
Interferone:
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
Innet Immuniety:
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
adaptive(acquired immuniety):
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
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.
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.