Innate Immunity -07 Flashcards
immunity
the ability of an organism to resist a particular infection or toxin by the action of specific antibodies or sensitized white blood cells; the immune system is principally concerned w/ the maintenance of homeostasis
Immunology
study of the immune system
what does the immune system protect us against?
pathogens, tumours, toxins, prions, allergens
what are the types of pathogens?
bacteria, virus, fungi, parasites
vaccination
introducing all or subunits of an “attenuated” or “inactivated” pathogen; cheapest way to reduce disease
what are the 3 levels of immunity?
intrinsic barriers, innate immunity (resident and induced defenses), adaptive immunity
intrinsic barriers
pre-formed barriers to prevent invasion; mechanical, chemical, physiological and microbiological
resident and induced defenses
complement, phagocytes, inflammation
complement defense
exist as precursor proteins throughout the body that get cleaved for activation; activated by anti-body-pathogen-binding/mannose-binding lectin/pathogens themselves and cause opsonization, membrane attack complex formation and inflammation
opsonization
an immune response in which the binding of antibodies to the surface of a microbe facilitates phagocytosis of the the microbe by a macrophage (“tagging”)
membrane attack complex (MAC)
molecular complex consisting of a set of complement proteins that forms a pore in the membrane of bacterial and transplanted cells, causing the cells to die by lysis
what are the types of phagocytes?
macrophages (resident in tissue), dendritic cells (resident in tissue), neutrophils
what are the phases in phagocytosis?
chemotaxis, adherence, ingestion, digestion, killing/elimination
how is inflammation initiated?
PRRs such as toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) expressed by microbes
what is the primary goal of inflammation?
to move the required components from the blood stream to the site of tissue injury (may also recruit additional cells from bone marrow), and it also serves to remove the injurious agent, stim. and assist the immune system and promote tissue healing
what are the three events that occur in inflammation?
vasodilation + increased vascular permeability, migration of leukocytes, tissue repair (healing)
what are the cardinal signs of inflammation?
rubor (redness), calor (heat), tumor (swelling), dolor (pain) and funcio laesa (loss of function)
rubor (redness)
vasodilation and increased blood flow
calor (heat)
more blood delivered and metabolically active immune cells that release heat
tumor (swelling)
plasma leaked out into tissue
dolor (pain)
tissue stretching detected by free nerve endings
leukocytosis
increase in the number of WBCs
where do blood cells originate?
bone marrow
what is the primary lineage of most innate immune cells?
myeloid lineage (w/ exception of the NK cell - lymphoid lineage)
what are the innate immune cells?
macrophages, neutrophils. dendritic cells, NK cells, granulocytes
macrophages
“sentinel cells” that phagocytose bacteria and dead cells, produce cytokines establishing the inflammatory response; more are recruited to sites of injury/infection when needed - they are also long-lived
neutrophils
found in very high quantities in the blood (60-70%), migrate to tissues during inflammation, are recruited by chemokines incl. IL-8, contain toxic granules that can kill invaders and MUST be regulated to prevent immunopathology - also short-lived and replenished by bone marrow
dendritic cells
antigen-presenting cells in the skin (Langerhans cells) that also differentiate from monocytes; bridge the gap b/w innate and adaptive immunity by activating T and B cells in lymph nodes and the splee
natural killer (NK) cells
kill virus infected cells w/ dangerous mutations by releasing cytotoxic granules (perforin, granzymes) causing cytolysis or undergo apoptosis
what are the types of granulocytes?
mast cells, eosinophils, basophils
mast cells
important in allergic rxns via histamine release, help battle parasite infection, implicated in allergies and found primarily in tissues
eosinophils
parasite infection and protection of mucosal surfaces (GI tract, lungs, genital tract)
basophils
also important in allergic reaction via histamine release, release heparin to reduce blood clotting and found primarily in blood
what is the innate response to extracellular bacteria?
phagocytosis by macrophages, releasing cytokines and chemokines to attract more monocytes and neutrophils; occurs in positive feedback until pathogen is cleared
what is the innate response to intracellular viruses?
infected cells produce anti-viral cytokines (interferons) and the following happens:
- temp. change (fever)
- decreased protein synthesis
- increased MHC expression
- recruitment of NK cells
- infected cells killed
- phagocytes clean up released virus and dead cell material
what happens if innate immunity fails?
the adaptive response will be activated
TLR 1
Peptidoglycan
TLR2
Peptidogylcan
TLR 3
double stranded RNA
TLR 4
LPS (NEG BACTERIA)
TLR 5
FLAGELLIN
TLR 9
Unmethylated CpG DNA
Compliments are activated by
antibody pathogen binding
lectin mannose binding
pathogens themselves
