Innate Immunity Flashcards
What are the two components of the innate immune system?
- cellular component
- humoral component
What are the two components of the adaptive immune system?
- humoral component
- cellular component
What is the difference between innate and adaptive immunity?
Innate immunity is not dependent on antigen, it is immediate, and does not leave any memory.
Adaptive immunity is antigen-specific, delayed in time, and leave memory.
What barriers does innate immunity use/provide?
- physical barriers (skin, mucus membrane)
- Humoral barriers (complement system)
- Cellular barriers (phagocytic system, NK cells)
What factors are involved in physical barriers of the innate immune system?
- Mechanical factors
- Chemical factors (fatty acids inhibit growth of bacteria, lysozyme and phospholipase in tears, saliva inhibit growth of infectious agents, low pH of sweat/gastric juices has antibacterial effects, surfactants such as opsonins in lungs enhance phagocytosis)
- Microbial factors
What are the mechanical factors of innate immunity?
- skin
- ciliary movement
- peristalic movement in GI tract washing effect of tears and saliva
- mucus layers in vagina, digestive tract and respiratory tract
What are the chemical factors of innate immunity?
- fatty acids inhibit growth of bacteria
- lysozyme and phospholipase in tears, saliva inhibit growth of infectious agents
- low pH of sweat/gastric juices has antibacterial effects
- surfactants such as opsonins in lungs enhance phagocytosis
What are microbial factors of innate immunity?
- Normal biota on skin and GI tract prevents infection by secreting inhibitory substances that prevent colonization and growth of infectious microorganisms.
What happens if the physical barriers of innate immunity are breached?
penetration of infectious agents and development of inflammation
What ar the most important humoral factors of innate immunity?
- complement system
- coagulative system
- Lactoferin and transferin
- Lysozyme
- Interferons
- Interleukin-1
What is the complement system?
a group of ~30 proteins found in serum that cooperate to prevent infection
What does activation of the coagulative system lead to?
- blood coagulation at the site of damage preventing entry to infectious agents
- some molecules of the system act as chemotactic factors, attracting other cells to the site of damage
- Beta-lysine is produced by platelets and has bactericidal effects against G+ bacteria
What does lactoferin and transferin do?
binds iron - bacteria cannot grow in the absence of iron
What does lysozyme do?
digests bacterial cell wall
What do interferons do?
inhibit infection and replication of viruses
What does interleukin-1 do?
responsible for increase in temperature during inflammation and induces acute phase proteins which are bactericidal
What are the cellular barriers of innate immunity?
- neutrophils
- Macrophages
- NK cells and LAK cells
- Eosinophils
What do neutrophils do?
belong to polymorphonuclear cells
- phagocytose microorganisms
What do macrophages do?
differentiate from monocytes and function as phagocytes
- ingest and kill microorganisms intracellularly
- may also phagocytose and kill infected cells
- may function as antigen presenting cells
- participate in wound healing
What do NK and LAK cells do?
kill infected or tumor cells
What do eosinophils do?
participate in eliminating parasites
Whata re the two vital cells of the phagocytic system?
Neutrofiles and macrophages
How are neutrofiles identified?
expression of CD66 on cell surface
What are the two types of granules stored by neutrofiles that store molecules required for the intracellular killing process?
- Azurophilic granules
- Secondary granules
What do azurophilic granules contain?
- defensins which kill bacteria
- proteolytic enzymes such as elastase, cathepsin G which degrade bacterial proteins
- Lysozyme which degrades the bacterial cell wall
- myeloperoxidase - required for the generation of bactericidal substances
What do secondary granules of neutrofiles contain?
- lysozyme
- lactoferin
- components of NADPH oxidase for production of toxic radicals
What are macrophages identified by?
the expression of CD14, CD11b, or F4/80
What are the lysosomes of macrophages used for?
they contain factors required for intracellular killing mechanisms
What do macrophages react to?
danger signals (SOS) generated at sites of pathogen entry
What are some danger signals that macrophages react to?
- N-formyl-methionine - secreted by bacteria
- Peptides of coagulative system
- complement system components
- cytokines secreted by tissue macrophages (at portals of entry)