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Immunology
Dr. Twana A. Mustafa
Introduction to Immunology
• Immunology is a branch of biomedical science that covers the study of immune
systems in all organisms, is the study of physiological mechanisms that humans and
other animals use to defend their bodies from invading organisms.
• The immune system is a network of cells, tissues, and organs that work together to
defend the body against attacks by “foreign” invaders.
• These foreign invaders are primarily microbes—tiny organisms such as bacteria,
parasites, and fungi that can cause infections. Viruses also cause infections, but are too
primitive to be classified as living organisms.
• The human body provides an ideal environment for many microbes. It is the immune
system’s job to keep them out or, failing that, to seek out and destroy them.
Immunology lingo
• Antigen
– Any molecule that binds to immunoglobulin or T cell receptor
• Pathogen
– Microorganism that can cause disease
• Antibody (Ab)
_
A protein that is produced by B lymphocytes and that interacts with a specific
antigen.
• Vaccination
– planned induction of protective immunity to a pathogen
• Immunization
– The ability to resist infection

Immune response:
_ The reaction of the immune system to an antigen.
Types of Immunity
• Innate Immunity
 refers to nonspecific defense mechanisms that come into play immediately or within
hours of an antigen's appearance in the body. These mechanisms include physical
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barriers such as skin, chemicals in the blood, and immune system cells that attack
foreign cells in the body.
 This means that the cells of the innate system recognize, and respond to, pathogens in a
generic way, but unlike the adaptive immune system, it does not confer long-lasting or
protective immunity to the host.
 Innate immune systems provide immediate defense against infection, and are found in
all classes of plant and animal life.
• Adaptive Immunity
 The adaptive immune system is composed of highly specialized, systemic cells
and processes that eliminate or prevent pathogenic challenges.
 The adaptive or "specific" immune system is activated by the innate immune
system.
 The adaptive immune response provides the immune system with the ability to
recognize and remember specific pathogens, and to mount stronger attacks each
time the pathogen is encountered.
 It is adaptive immunity because the body's immune system prepares itself for
future challenges.
• Cells of the immune system:
– Neutrophils.
– Lymphocytes.
– Monocytes/Macrophage.
– Dendritic Cells.
– Mast Cells.
– Eosinophils.
– Basophils.
– Other Blood Cells: Megakaryocytes and Erythrocytes.
 Organs of the Immune System:
There are two groups of immune system organs.


Primary (central)--organs where immature lymphocytes develop
o Thymus
o Bone marrow
Secondary (peripheral)--tissues where antigen is localized so that it can be effectively
exposed to mature lymphocytes
o Lymph nodes
o Appendix
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Peyer's Patches (of GI tract)
Tonsils
Adenoids
Spleen
MALT (Mucosal-Associated Lymphoid Tissue)
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