Download Non-specific Immunity

Non-specific Immunity
“First Line” of Defense
• Physical barrier on all surfaces of body
exposed to external world
• What are they?
– Skin
– Mucous membranes—nasal, respiratory
– Lining of mouth
– Lining of gut
– Lining of vagina/urethra
– Surface of eye
Skin
Barrier
Membranes
How do barrier membranes keep
bacteria out?
• Chemical barrier—antibacterial secretions
• Cellular barrier—cells tightly packed and
sloughed off (10B skin cells/day=250 g./year)
• Physical barrier—thick, mucousy and sticky
secretions trap bacteria
• Resident microbes—have commensal or
mutualistic bacteria and fungi that are normally
present and out-compete potential pathogens
Second Line of Defense
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Phagocytosis
Inflammation
Complement
Fever
All work tightly with specific immunity
(coming next)
Phagocytosis
• Phagocytes move through blood and
lymph and into connective tissues (part of
inflammation response as cells and fluid
move out of capillaries into surround
aleolar tissues--diapedesis)
•Langerhans cells in skin
•Phagocytes in blood
•Microglial cells in CNS
Complement
• Group of free proteins in blood that
respond to antigen/antibody complex
(huh?—coming soon)
• Cascade of reactions eventually makes
MAC’s—membrane attack complex—that
bores hole in bacterial membrane
• Gram-negative bacteria more susceptible
Inflammation
• Response to tissue damage from any
source (burn, cut, pathogen, other??)
• Blood vessels dilate allowing for better
delivery of nutrients, O2, antibodies,
complement, immune cells
• Phagocytes (monocytes and neutrophils)
migrate out of capillaries--diapedesis
Fever
Trigger not completely understood
Muscular contraction and constriction of skin blood vessels cause core temperature to rise
• Pluses
• Inhibit microbial
growth
• Enhance immune cell
performance
• Speed tissue repair
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Minuses
Malaise
Body aches
chills
“Breaking” fever or “crisis of fever”:
• body begins to cool by sweating,
• “color returns” as blood vessels in skin open
• Indicates infection is overcome
Links to Specific Immunity
• Phagocytosis continues to be common way to
kill pathogenic cells in both specific and nonspecific response
• Inflammation works to allow both specific and
non-specific immune response to accelerate
• Fever also allows for better performance in
both specific and non-specific function
• Specific immune response and “antigen
presentation” further stimulates non-specific
actions like phagocytosis, complement.
Great review of “Body Defenses” or
Non-specific Immunity
http://fajerpc.magnet.fsu.edu/Education/2010/2010_INDEX.HTM