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Immunology
BIT 120
Chapters 11
Immunity
Ability of body to defend against infectious agents, foreign cells, abnormal cells
Antigen: foreign substance/molecule which elicits an
response
 from virus, bacteria, mold, cancer, pollen
immune
Antibody protein found in blood attacks to one
particular kind of
antigen and counters its
effect specifically binds to antigens and
marks them for destruction
Non-Specific Immunity:
First Line of Defense
Does NOT distinguish between one invader and another
1. Skin
2. LYSOZYME in sweat, saliva, tears
enzyme which breaks bacterial cell wall
3. mucous membranes line digestive and respiratory tract
4. acid in stomach
5. hair, cilia in respiratory tract
Non-specific Immunity:
Second Line of Defense
FIGURE 11.1 BLOOD CELLS
1.Inflammatory reaction (Fig 11.5)
•injury
•injured cells release histamine
•Dilation of capillaries (increases blood flow)
•Increases permeability of caps
•Allows: Macrophages move to tissue to eat invader
Effects: Redness, heat, swelling, pain
Anti-inflammatory drugs- aspirin, ibuprofen
Non-specific Immunity:
Second Line of Defense
2.Interferon
released by virally infected cells
interferes with viral production of neighboring cells
3. Phagocytes (engulf microorganisms)
A. Macrophages
B. Neutrophils
releases chemicals
4. Natural killer cells
cause infected cells to lyse PERFORIN
cancer cells
Macrophages
Specific Immunity:
Third Line of Defense
•Comes into play when non-specific can’t do the job.
•Specific for particular virus or bacteria
Explain about not getting same sickness twice.
10E6 antigens in lifetime
KEY FEATURES
Lymphocytes (type of white blood cells)
B cells
T cells
T
L
Y
M
P
H
O
C
Y
T
E
Lymphocytes originate
in Bone Marrow
B Lymphocytes
•circulate in blood and lymph
•secretes antibodies
•only responds to free antigen
•defends against bacteria and virus
•
T lymphocytes
circulate in blood an lymph
attacks body’s cells that have been
infected with bacteria and virus
only responds to antigen on
body’s cells (needs APC)
also defends agst protozoans
fungi, cancer
T cell Mediated Immunity
Types of T Cells
Helper
Cytotoxic
Memory
•Microbe is ingested by macrophage
Foreign protein is displayed on surface
Helper T cells recognize foreign protein with their receptor
1. make more helper T cells
2. stimulate growth of cytotoxic T cells (which lyse
cells with perforin)
3. activate B cells to make antibodies
•Memory T cells
Antibody-Mediated Immunity
Humoral Response
1. B cell coated with its antibody (Immunoglobulin)
Antigen binds to Ab of one ‘clone’
2. CLONAL SELECTION
B cells becomes activated and divides/differentiates into
•plasma cells which produce antibodies
•Memory cells
Secondary immune response is stronger and longer
THIS SELECTION CAN ALSO BE STIMULATED BY HELPER T CELLS INTERACTING WITH B
CELLS (Fig 11.9)
3. Free Antibodies bind to antigen and cause phagocytosis and cell lysis
Antibody
Fig 42.6
FIG 42.11
Macrophages and E. coli
Allergies
Hypersensitivities to substances that are not harmful to body –
•pollen
•animal hair
Caused by IgE on mast cells
When antigen binds to antibody,
histamine is released from mast cell
Histamine causes cold-like symptoms
•nasal irritation
•tears
•blood vessels dilate
Anaphylactic Shock
Extremely sensitive to allergen
Mast cells release histamine
Blood vessels dilate
Precipitous drop in Blood Pressure (SHOCK)
Possibly fatal
Treatment
Epinephrine
Increases blood pressure
Autoimmune Diseases
Body doesn’t distinguish between self and non-self correctly
lupus
insulin-dependent diabetes
rheumatoid arthritis
multiple sclerosis
Immunodeficiency Diseases
•SCID severe combined immunodeficiency
no B or T cells
TREATMENT Gene therapy
•AIDS
•Stress
Exams vs vacation research
decreased interferon levels and
decreased natural killer cells