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 facilitate
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 functions.
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
Also skine secretion of sweat & seabessus
which is antibacterial & antifungal and mucus
membranes
of antibacterial &antivirus
secreation
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 Nonspecific immunity is Interferon(INF)
Interferon :It is family of cytokines
produced by a wide variety of cell
such as fibroblast, macrophage &
epithelial cell they induce by viruses
that which block the viruses invade
from infected neighbear cell of the
host .
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
Foreign to host of immune system
there for any microorganism get
into the body host and it is foreign
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 Tlymphocyte.
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