Dr.Fadwah AlGhalib
Basic Immunology
2nd yr 2009
(1st Lecture)
Introduction of the immune system
Objectives:
1-Define what is immunology? What is Immunity? What is Antigen? What
is antibody?
Immunology: is the study of the immune system
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
Antigens: are substances that can stimulate an immune response, that react specifically by
binding to effector molecules (antibodies) and effector cells ( T lymphocytes).
Define Homeostasis? Hemeos (the same) stasis (standing): Is the maintained steady-state
conditions existing in healthy individuals.
-2 -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)
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Dr.Fadwah AlGhalib
Basic Immunology
2nd yr 2009
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.
Granular Leukocytes: Neutrophils
Basophils
Eosinophils
4-What are the types of the immune responses?
a. Natural (non-specific)
b. Adaptive (specific)
-What are the cellular components for each immune responses?
Natural immunity:
1- Cells: such as : Phagocytic cells (Neutrophils and Macrophages)
Cells
2- Soluble molecules:- Complement
- Cytokines : such as interferone and TNF
Adaptive Imunity:
There are two major branches of the adaptive immune responses:
humoral immunity
and
cell-mediated immunity.
Humoral immunity: involves the production of antibody molecules in response to an
antigen
and is mediated by B-lymphocytes
Cell-mediated immunity: involves the production of cytotoxic T-lymphocytes,
And activated macrophages, activated NK cells, and cytokines in response to an antigen
and is mediated by T-lymphocytes.
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