Dr.Fadwah AlGhalib
Basic Immunology
2nd yr 2011
(1st Lecture)
Introduction of the immune system
Objectives:
1-Define what is immunology? What is Immunity? What is Antigen? What
is antibody? Homeostasis?
2- Define
the terms , "intra" and " extra" cellular pathogens, immune
response and inflammation?
3- Describe and classify the cells of the immune system.
4- Classify the elements of the immune system in regarding to :
a. the type of the pathogen recognition " specific or non-specific immune
response"
b. the type of the immunological element involved in the immune
response either cellular or humoral (non-cellular).
5- Explain the "main functions" of the immune system.
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Definitions:
Immunology: is the study of the immune system
System: The whole unit which composed of different elements to perform a
specific function. [ e.g: respiratory system, digestive system, immune system..etc...]
Immune system: is a collection of cellular elements & non cellular (humoral)
elements. They do not interact with self components, but respond ( interact) to non-self
components and destroy them.
Immune Response:
the reaction of an organism's body to foreign materials
(antigens), including the production of antibodies
Immunity: The ability of the body to defend itself against specific invading agents such
as bacteria, toxins, viruses and foreign tissues.
Antibody: are proteins that are formed in response to an antigen and that react
specifically with that antigen
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Dr.Fadwah AlGhalib
Basic Immunology
2nd yr 2011
Antigens: are substances that can stimulate an immune response, that react specifically
by binding to effector molecules (antibodies) and effector cells ( T lymphocytes).
Intracellular pathogens: enter inside the human cells and multiply. [ All viruses
and some protozoan, some bacteria,]
Extracellular pathogens: Exist outside the host cells (human cells). [ large
parasites, and many bacteria] they live in tissues & body's fluid.]
Where exactly in our body do these pathogens lives and multiply????
Define Homeostasis? Hemeos (the same) stasis (standing): Is the maintained steady-state
conditions existing in healthy individuals.
What are the functions of the immune system?
a. Surveillance (recognition of non-self) the antigen
b. Defence: initiating an immune response, The immune system can eliminate threats by
isolation, disruption, or ingestion or by combination of the three actions
c. Regulation:
i--control of the immune responses to maintain hemeostasis, and return the immune
system to a state that existed before the antigenic stimulation.
ii--To prevent tissue injury that may result from an exaggerated immune Response.
d. Immunity (immunological memory): state of resistance (acquired protection)
following exposure to a stimulating agent
e. Tolerance: induction of a state of unresponsiveness toward certain antigens (mainly
self-antigens)
3-What are the cells of the immune system?
Agranular Leukocytes and
Granular Leukocytes
Agranular Leukocytes:
Plasma cells
Monocytes (are phagocytic cells in circulation) in tissues are
Macrophages
Dendritic cells ( are phagocytic cells)
Lymphocytes (T, B, & NK cells)
Granular Leukocytes: Neutrophils , Basophils, Eosinophils
4-What are the types of the immune responses?
a. Natural- innate- (non-specific)
b. Adaptive- acquired- (specific)
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Dr.Fadwah AlGhalib
Basic Immunology
2nd yr 2011

What are the cellular components for each immune
responses?
1) Natural immunity:
1- Cells:
I) Phagocytic cells ( internalize pathogen and kill) & others do not.
It is classified into 2 types according to their nuclear shapes and number.
a- polymorphonuclear phagocytes:
includes Neutrophils (short lived cells) and
Eosinophils.
b- Mononuclear phagocytes: includes Monocytes and macrophages (long lived cells) and
dendritic cells.
II) Non-phagocytic cells:
a- Auxiliary cells such as Mast cells, Basophiles, & platelets
b- Tissues cells (some epithelial cells).
2- Soluble molecules:- Complement [is the major humoral non-specific defence
mechanism]
-
2) Adaptive Immunity:
There are two major branches of the adaptive immune responses:
a- humoral immunity
and
b- cell-mediated immunity.
a- Humoral immunity: involves the production of antibody molecules in response to
an antigen and is mediated by B-lymphocytes
Some components of the humoral immunity ( Soluble mediators' of immunity):
1- immunoglobulins ( IgA, IgG, IgM, IgD, IgE)
2- Cytokines ( interferone, interlukines, & colony stimulating factors)
3- Acute phase proteins ( C-reactive proteins)
4- Complement (C1-C9)
b- Cell-mediated immunity: includes the LYMPHOCYTES. B CELLS, AND T
CELLS.
i- B CELLS: differentiate to plasma cells which produces the soluble immunoglobulins.
ii- T CELLS:
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Dr.Fadwah AlGhalib
Basic Immunology
2nd yr 2011
There Are Four Main Types Of T-Cells:
a- Helper T-cells –.
1) They secrete lymphokines (cytokines) which are hormones that stimulate other cells in
the body to resist invading antibodies.
2) They display the protein CD4 on their surface;
3) which assist in both cell mediated immunity (CMI) and Antibody-mediated immunity
(AMI).
b- Killer T-cells –
1) which kill antigens directly once stimulated by agents released by the helper T-cells.
2) They display the protein CD8 on their surface;
c- Suppressor T-cells – are a controversial cell that is believed to dampen or
suppress the immune response
d- Memory T-cells - which recognise the original invading antigen. When the antigen
returns thousands of memory cells are available to initiate a far swifter reaction than
occurred during the first invasion.
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