Immunology Flashcards
name physical barriers in which pathogens can breach
lungs, GI tract, reproductive tract, skin
where do T-lymphocytes mature?
thymus
what 3 cells leave the blood and take long-term residency in tissues?
dendritic cells, macrophages and mast cells
where do B and T lymphocytes spend most of their life?
secondary lymph organs
name the 5 secondary lymph organs
peyers patches, appendix, spleen, lymph nodes, tonsil
name the WBCs in the adaptive immune system
B and T lymphocytes
(other WBCs all innate)
what do B and T lymphocytes produce in the adaptive immune response?
B - antibodies
T - effector T cells
what are the 3 ways complement can be activated and how does each one work?
classic - antigen/antibody complexes
MB-lectin - lectin binding to pathogen surfaces
alternate - pathogen surfaces
what 3 things occur after complement activation?
inflammatory cell recruitment
opsonisation of pathogens
killing of pathogens
what is complement?
a cascade of proteins in serum
what is the mechanism pathway of innate immunity?
infection -> recognition by performed nonspecific effectors -> infectious agent removal
what is the mechanism pathway of the early induced response?
infection -> recruitment of effector cells -> recognition activation of effector cells -> infectious agent removal
what is the mechanism pathway of the adaptive response?
infection -> transport antigen to lymphoid organs -> recognition by naive B/T cells -> production of effector cells -> infectious agent removal
describe the characteristics of neutrophils
short lived (6-12 hours)
first line of defense
phagocytose pathogens
release soluble mediators
what do 1st degree granules in neutrophils contain?
bactericidal enzymes (lysozyme, neutral proteases, acid hydrolases, myeloperoxidase)
what do 2nd degree granules in neutrophils contain?
lysozyme, collagenase, lactoferrin, cathepsin B
what are the 4 steps to innate cells migrating to infection sites?
rolling adhesion, tight binding, diapedesis, migration
how do macrophages act on pathogens?
they reorganise their actin cytoskeleton to engulf bacteria digested in the cell
what are pseudopodia?
macrophage extentions that engulf apoptotic cells
describe the characteristics of macrophages
developed in tissues from precursors
active phagocytic cells
activated by inflammation
long lived
where is the antigen concentrated when arriving via lymph?
lymph nodes
describe the humoral adaptive immune response
antibody (from B cells) mediated extracellular attack
describe the cell mediated adaptive immune response
T cell coordinated intracellular attack
where do B cells mature?
bone marrow
what are B cell receptors?
an antibody (surface immunoglobulin)
what are the 5 stages of the adaptive immune response?
antigen recognition, lymphocyte activation, antigen elimination, contraction (homeostasis), memory
explain the structure of an antibody
bivalent monomer: 4 polypeptide chains (2 light, 2 heavy)
antigen binding fragment (Fab)
crystalline fragment (Fc) - binds cells/complement
what are the 6 functions of antibodies?
agglunitation
opsonisation
neutralisation
cytotoxicity
inflammation
complement activation
(ICONAC)
explain agglutination
enhances phagocytosis and reduces number of infectious units to be dealt with
explain opsonisation
coating of antigen with antibody to enhance phagocytosis
explain antibody neutralisation
blocks adhestion of bacteria and viruses to mucosa
blocks active site of toxin
explain antibody-dependant cell-mediated cytotoxicity
antibodies attached to target cell
non specific immune system cells come and destroy it
explain antibody inflammation
cell disruption by complement, which attracts phagocytic/defensive immune cells
what do helper T cells do in cell mediated immunity?
help B cells
help cytotoxic T cells
direct innate responses
explain the structure and subdivision of T cells in relation to CD(number)’s
T cell receptor on surface, CD3 identifies cells
further subdivided by expression of one of 2 surface molecules: CD4 or CD8
what do CD4 T helper cells do?
recognised antigen presented in MHC 2 on antigen-presenting cells surface and ‘help’ them
what do CD8 cytotoxic T cells do?
recognise antigen presented in MHC 1 on many cell types and can be induced to kill
name 3 signals T cells need for activation
antigen presented in context of MHC
surface molecule costimulation
soluble molecules (cytokines)