lecture 3 IMM.docx - lecture 3 – innate immunity : the...

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lecture 3 – innate immunity : the first line of defense toinfection pt. 2SOLUBLE MEDIATORS OF INNATE IMMUNITY(cytokines & complement)pathogen breaches barrier(using virulent factors)and thenreleases PAMPsdetected by PRRactivates signal transductionactivatesNFBcontrols the production of soluble mediators of innate immunity (e.g., cytokines)what are cytokines?CYTOKINE: a category ofSIGNALING MOLECULESthat (like hormones and neurotransmitters)are used extensively inCELLULAR COMMUNICATION; cytokinesgenerally enhance the ability ofour cells to get rid of an invading pathogen and promote healingfeatures of cytokines :diverse collection ofsoluble proteinsthatmodulate the behaviour of cellsat extremelysmall concentrationsact bothlocally(around the cell) andsystematically(recruited)have many biological activities ; changes the behaviour of cells in many different ways(PLEIOTROPIC EFFECTS)cytokines are soluble molecules of immunityproduction of cytokines is amain method of communicationbetween cellsimmune cells produce many different cytokines that can act on the same producing cellsor on other cells to alter their functiondepending on the type of infection, there are different pathways :
complement is another soluble mediator in innate immune responsesa complex network of plasma and cell surface proteinsoperates in a manner similar to the blood clotting cascadeone active factor activates an inactive factor which then activates another inactive factor:ZYMOGENSorPRO-ENZYME, an inactive enzyme precursor that requires abiochemicalchange to become activeallows for a huge amplificationtriggers for activating the first factor :omicrobial patters (PAMPs)oimmune complexes – complexes between antibody and non-self proteinsCOMPLEMENT: effector molecules of innate immunity(can be activated through 3 ways and results in 3 different pathways)COMPLEMENT EFFECTOR MECHANISMS1)the membrane attack complex or MAC(bacterial cell lysis)

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