Non-specific Immunity
Dec 17, 2015
“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
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
• Phagocytosis
• Inflammation
• Complement
• Fever
• All work tightly with specific immunity (coming next)
• 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)
Phagocytosis
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
• Pluses• Inhibit microbial
growth• Enhance immune cell
performance• Speed tissue repair
• Minuses• Malaise• Body aches• chills
Trigger not completely understoodMuscular contraction and constriction of skin blood vessels cause core temperature to rise
“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 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.
Great review of “Body Defenses” or Non-specific Immunity
http://fajerpc.magnet.fsu.edu/Education/2010/2010_INDEX.HTM