Information Technology Reference
In-Depth Information
Chapter 1
Immunology Basics
In medicine, historically, the term “immunity” refers to the condition in which
an organism can resist diseases, more specifi cally infectious diseases. However, a
broader defi nition of immunity is the reaction to foreign substances (pathogens),
which includes primary and secondary immune responses.
Mammals have developed a robust defense system called the
immune system
to deal with foreign and potentially dangerous pathogens. h e immune system
consists of a set of organs, cells, and molecules; and their coordinated response in
the presence of a pathogen is known as the
immune response
. In a broader sense, the
physiological function of the immune system is to defend an organism against all
kinds of harmful substances such as fungi, bacteria, parasites, viruses, and other
protozoa. However, noninfectious external substances can also generate immune
responses (Abbas and Lichtman, 2005).
In general, antigens are capable of inducing an immune response as they are
assumed to be harmful nonself invaders in the body. h e ability of an antigen to
induce an immune response probably depends on four main factors: foreignness,
molecular size, chemical composition and heterogeneity, and susceptibility to anti-
gen processing and antigen presentation.
h e biological immune system (BIS) has the ability to detect foreign substances,
and to respond adequately. It is inherently distributed and fault-tolerant, and exhib-
its a complex behavior while interacting with all its constituents. One of the main
capabilities of the immune system is to distinguish own body cells from foreign
substances, which is called
self/nonself discrimination
. In general, the BIS is capable
of recognizing the dangerous elements and deciding an appropriate response while
tolerating self-molecules and ignoring many harmless substances.
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