principles of immune response Flashcards
soluble mediators: define cytokines and complement and describe their pathways and functions
define cytokines
any small soluble protein mediator secreted by certain cells of the immune system that have an effect on other cells
in macrophages, what initiates a response release of cytokines
bacteria binding to macrophage receptor
what cells secrete cytokines in innate immunity
macrophages, mast cells, natural killer cells
what cells secrete cytokines in adaptive immunity
T and B lymphocytes, dendritic cells
what complement proteins activate mast cells
anaphylatoxins
what cytokine do natural killer cells secrete
interferon-y
3 features of mode of action of cytokines
generally act locally, biological effects at very low concentrations, short-lived
5 types of cytokines
interleukins, interferons, chemokines, growth factors, cytotoxic
what cells do interleukins communicate between
leukocytes
what effect do type 1 interferons have
anti-viral
what are chemokines involved in
chemotaxis
what 2 effects do growth factors have
proliferation, differentiation
what do cytotoxic cytokines induce
cell death, e.g. tumour necrosis factor (TNF)
cytokine mode of action
work by binding to specific receptors on target cells, causing specific gene activation; one cell produces a cocktail of cytokines; diagram
what is the major role of the complement system
complementing activity of specific antibody in lysing bacteria
how is the major role of the complement system performed
a protein cascade occurs where holes are rapidly punched in the microbial outer membrane, coated for phagocytosis (opsonisation) and the production of chemoattractants for cell recruitment
what is opsonisation
coating of microorganisms with proteins (opsonins) to facilitate phagocytosis; opsonins bind to antigen and phagocytes
how many (glyco)proteins are involved in the complement system
30 in serum and tissue
what forms the activated proteins
triggered enzyme cascade system
describe the triggered enzyme cascade system
inactive enzymes present as precursors in liver (humoral) → initial event rapidly amplified → parts of enzyme cleaved → rapidly amplified
4 functions of complement system
lysis (not phagocytosis), opsonisation, activation of inflammatory response, clearance of immune complexes
what are the 2 types of opsonin
antibodies, complement proteins
3 complement activation pathways
classical, lectin, alternative
describe classical complement activation pathway
antigen and antibody interaction (pro-inflammatory molecules)
