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Immunity
Adapted from Adlai E. Stevenson High School
Primary Function of the Immune
System
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Provides protection against disruption by
pathogens or toxins
Helps discriminate between “self” and
“nonself”
Pathogen - Definition:
– Any disease causing agent (microorganisms)
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Types:
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Bacteria
Viruses
Parasites
Fungi
The Defenses
Non-Specific
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Definition:
– Agents do not have to recognize a foreign invader
to fight it (work by preventing pathogen from
entering the body)
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Examples:
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Skin
Tears
Saliva
Sweat
Mucus
Macrophage
The Defenses
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Definition:
Specific
– Agents attacks only certain invaders, specialized
defense
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Types of Cells
– Helper T cells
• 1st line of specific defense
• Help recruit other immune cells & tell them to attack
certain invaders
– Killer T cells
• Can distinguish virus infected cells from uninfected cells
by the unique molecular signals on the infected cells
surface
– B cells
• Told by helper T cells to make antibodies to prevent
specific antigens from hurting the body…. “Memory”
Lymphocyte Function
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T cell response
– Attach to foreign
antigen bearing
cells and interact
directly
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B cell response
– Differentiate into
plasma cells
– Produce
antibodies
Cell Mediated
Immunity
Humoral
Immunity
Antibodies & Antigens
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Proteins
Can recognize
chemical signals
from another cell
(pathogen)
“Self”
Y shape
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Chemical signal on
the surface of a
pathogen
Cell Mediated Immunity
Cytotoxic T cells
Killer T cells recognize body cells infected with a virus; then
destroy those cells by drilling holes in their plasma
membranes.
Cell or Antibody Mediated Immunity
Helper T cells
Helper T cells start the immune response by activating B
or T cells.
T cells and cell-mediated immunity
Macrophage
Antigen-presenting cell
cytotoxic
T cell
suppressor
T cell
Helper T cell
Antigen-presenting cell
APC
B cell
Antibody Mediated Immunity
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B cells
– Activated when it
encounters an
antigen that fits its
antigen receptor
– Proliferates (colonial expansion)
• Plasma cells->antibodies
• Memory cells-->future
fights
Vaccines
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What is in the shot they give you?
– Dead or inactive (attenuated) pathogens
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How does it work?
– Cause B cells to make antibodies against
the foreign antigen
The Memory of Infection
Autoimmune Disorders
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“Auto” = self
Definition: a disease in
which the immune
system attacks the
tissue of the body;
cause is generally
unknown
Immune system
distinguishes “self”
from “non-self
Examples:
– multiple sclerosis (MS) T cells destroy myelin
sheath around neurons
Cold Virus, Rubella, & Strep
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Common Cold Virus
– Influenza; contagious viral
infection of the nose, throat and
lungs which often occurs in the
winter.
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Rubella virus
– German measles
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Streptococcus
bacterium
– Strep throat is an infection of
the pharynx caused by
streptococcus bacteria.
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Treatments:
– Strep Throat
• Antibiotics such as
penicillin or
erythromycin
– Rubella
• Vaccine
– Influenza