646
646
Cells Mediating Immune Defenses
Cytokines
Nonspecifi c Immune Defenses
Defenses at Body Surfaces
Infl
ammation
Interferons
Specifi c Immune Defenses
Overview
Lymphoid Organs and Lymphocyte
Origins
Functions of B Cells and T Cells
Lymphocyte Receptors
Antigen Presentation to T Cells
NK Cells
Development of Immune Tolerance
Antibody-Mediated Immune Responses:
Defenses Against Bacteria,
Extracellular Viruses, and Toxins
Defenses Against Virus-Infected Cells
and Cancer Cells
Systemic Manifestations of Infection
Factors That Alter the Body’s
Resistance to Infection
Acquired Immune Defi
ciency Syndrome
(AIDS)
Antibiotics
Harmful Immune Responses
Graft Rejection
Transfusion Reactions
Allergy (Hypersensitivity)
Autoimmune Disease
Excessive Infl
ammatory Responses
Additional Clinical Examples
Systemic Lupus Erythematosus
chapter
18
Defense
Mechanisms of
the Body
i
mmunology
is the study of the
physiological defenses by which
the body (the host) recognizes
itself from nonself (foreign matter).
In the process, it destroys or
neutralizes (renders harmless) foreign
matter, both living and nonliving.
In distinguishing self from nonself,
immune defenses (1) protect against
infection by
microbes
—viruses,
bacteria, fungi, and parasites;
(2) isolate or remove nonmicrobial
foreign substances; and (3) destroy
cancer cells that arise in the body,
a function known as
immune
surveillance.
Immune defenses, or immunity, can
be classifi ed into two categories:
nonspecifi c and specifi c, which
interact with each other.
Nonspecifi
c
immune defenses
protect against
foreign substances or cells without
having to recognize their specifi c
identities. The mechanisms of
protection used by these defenses
are not unique to the particular
foreign substance or cell.
Specifi
c
immune defenses
(also called
acquired immunity) depend upon
Human
immunodefi
ciency
viruses budding
from a T cell.
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