Fighting Infection Flashcards
what is the innate immune system
common set of responses turned on my most microbial agents
t-cells and b-cells are part of the innate immune system, also macrophages and granulocytes
what is the adaptive immune system
individual response to specific antigen exposure
capable of change during response ‘adaptation’
what are the four components of the innate immune system
physical barriers (epithelial surfaces), cellular components (phagocytes and NK cells), cpmplement system and mediators of inflammation, cytokines
what is the purpose of physical barriers in the innate immune system
secrete antimicrobial substances (defnesins), secretion by cytokines, epithelia also contain lymphocytes and mast cells, peritoneal lymphocytes secrete antibodies against LPS
what is the purpose of cellular components in the innate immune system
neutrophils, macrophages and dendritic cells to phagocytose or present antigens to pathogens
what are neutrophils
larged mulitlobed nuclei with many organelles,
phagocytosis, reactive oxygen and nitrogen species, antimicrobial peptides
what are macrophages
large rounded nucleus, many organelles,
phagocytosis, inflammatory mediators, antigen presentation, reactive oxygen and nitrogen species, cytokines, complement proteins
what are dendritic cells
large cells with small nucleus:cytoplasm ratio, membrane protrusions
antigen presentation, costimulatory signals, reactive oxygen species, interferon, cytokines
what structures on microbes are not present in mammalian cells
mannose receptors, receptors for opsonins, toll-like receptors, 7TM alpha helical receptors
what is the result when pathogens bind to receptors on innate cells
phagocytosis of pathogen by macrophages or neutrophils, killing of infected cell by NK cells, presentation to T cells by APCs (dendritic cells)
what are toll-like recptors
similar to drosophila toll rec
found on most cells of innate immune system
respond to variety microbial markers
result in upregulation of inflammatory gene expression
what are lipopolysaccharides
endotoxins, product of gram negative bacterial cell wall, stimulates innate immune system, pathogenic- induces local and systemic inflammation, potent activator of macrophages inducting cytokine release and reactive oxygen (superoxide) bursts, systemic inflammatory response syndrome (SIRS) - fever, neutrophilia, septic shock
what is phagocytosis
mediated by neutrophils and macrophages, neutrophils are the most number WBCs and first on the scen
microbe binds to cell surface receptors and is endocytosed, phagosome fuses with lysosomes containing degrading enzymes - lysosome, collagenase and elastase
reactive oxygen species - superoxide, hydrogen peroxide, nitric oxide
what are the steps of phagocytosis
bacterium attaches to pseudopodia, becomes ingested which forms a phagosome, phagosome fuses with lysosome, lysosomal enzymes digest captured material, digestion products are released from cell
what is the complement system
cascade of plasma proteins, activated by microbes resulting in their destruction, zymogens (gain enzymatic activity by clevage)
leads to opsonisation and phagocytosis
