Transcript Nonspecific Immunity

Nonspecific Immunity
What is non specific immunity?
• Protects regardless of pathogen
• Includes first and second line of defense
– We’ll discuss third line in another lecture!
First line of defense
What is the first line of defense?
• Physical barriers
• Chemical barriers
• Normal Microbiota
What are physical barriers?
• Skin
– Epidermis
• Many cells packed
tightly
• Keratin
• Arid
• Benign microbes
• sloughing
– Dermis
• Infections most likely
from
– Subcutaneous
staphylococci
What are chemical barriers?
• Lysozyme
• Mucous
membranes
• Lacrimal
apparatus
• Saliva
• Mucociliary
escalator
• Epiglottis
• Urine
• Vaginal
secretions
• Lactic acid
mantle
Normal Microbiota
• Microbial antagonism/competitive
exclusion: Normal microbiota compete
with pathogens.
–
–
–
–
Candida albicans
E.coli
Salmonella
Shigella
Second line of defense
What constitutes the second line of defense?
• Phagocytosis
• Inflammation
• Complement
• Interferons
What are phagocytes?
• Literally means
___________
• All are
leukocytes
• Neutrophils
• Leukocytes
• Monocytes
– Macrophages
• Eosinophils
• Basophils
How do phagocytes work?
• Adherence
• Phagosome
• Phagolysosome
Does phagocytosis always work?
• Nope!
• Adherence inhibition
– Streptococcus pyogenes M
protein
– Capsules also
• H pylori, Streptococcus
pneumoniae
• Ingested but still alive
– Staphylococcus
leukocidins
– Streptococcus streptolysin
Staphylococcus
Does phagocytosis always work?
• Mycobacterium tuberculosis, HIV,
Chlamydia, Plasmodium
– Prevents fusion and acidification of enzymes
– Multiply within phagocyte
Chlamydia inclusion on pap smear cell
How do leukocytes get to a wound?
• Diapedesis
• Chemotaxis
What about
inflammation?
•
•
•
•
Pain
Redness
Swelling
Heat
• Acute
inflammation
– Boil: S. aureus
• Chronic
inflammation
– M. tuberculosis
What is fever?
• Pyrogens
– Exogenous
• Some viruses, endotoxins
– Endogenous
• Interleukin I
• Inhibits pathogens
• Reduces iron availability
• Stimulates immune response
The Complement System
• Serum proteins
activated in a
cascade.
Figure 16.9
Effects of Complement Activation
• Opsonization or
immune
adherence:
Enhanced
phagocytosis.
• Membrane attack
complex:
Cytolysis.
• Attract
phagocytes.
Figure 16.10
Effects of Complement Activation
Figure 16.11
What happens
with complement?
– 20 subunits
– Cascade
reaction
– Classic
pathway
• Binding to
mannan
stimulates
– Animation
What happens
with complement?
– 20 subunits
– Cascade
reaction
– Lectin
pathway
• Binding to
mannan
stimulates
– Animation
What are interferons?
• Antiviral
– Induce antiviral protein production
– Causes neutrophils and macrophages to phagocytize bacteria.
– animation