Transcript Non-specific Immunity

Immunity—non-specific/innate
• Overview of immune response
• First line of defense—barriers
• Second line of defense
– Phagocytosis
– Inflammation
– Complement
– Fever
• Relationship to specific immune response
or Third line of defense
Immune Response—Overview
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
• First line of Defense—physical
barrier
• Second Line of Defense
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Phagocytosis
Inflammation
Complement
Fever
All work tightly with specific immunity
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
Minuses
• Inhibit microbial growth
• Enhance immune cell
performance
• Speed tissue repair
• 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 from innate (2nd line) to specific/adaptive (3rd line) Immunity
• Phagocytosis continues to be common way to kill pathogenic cells in both
specific and non-specific 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.
Links from innate (2nd line) to specific/adaptive (3rd line) Immunity