Components of the Immune System Flashcards
where do all immune cells come from?
hematopoeitic stem cells
what do hematopoeitic stem cells do?
differentiate into myeloid progenitor cells and lymphoid progenitor cells
what do myeloid progenitor cells become? (5)
- granulocytes
- monocytes
- macrophages
- platelets
- erythrocytes
what do lymphoid progenitor cells become? (3)
- lymphocytes
- dendritic cells
- natural killer cells
what do granulocytes contain?
cytoplasmic granules
what happens to granulocytes when they come into contact with antigen?
the contents of their cytoplasmic granules are released and will perform different functions based on cell type
what are the 4 granulocytes? which of those 4 is NOT a white blood cell?
- neutrophils
- eosinophils
- basophils
- mast cells- NOT white blood cells
where are neutrophils found?
circulate in bloodstream for a short period of time (less than 10 hours) and then migrate into tissues, where they live up to 10 days and then die
what is the function of neutrophils?
- perform phagocytosis of antigen
2. secrete contents of granules which will attract other immune cells to site of infection
what is the most abundant of white blood cells, making up over 50% of circulating WBCs?
neutrophils
why are neutrophils the first responders in an infection?
they are already in the tissues at time of infection
do birds have neutrophils? if no, what do they have instead?
not neutrophils; have heterophils which are the same as neutrophils; just stain differently
what are eosinophils specialized for?
to fight of multi-cellular parasites
what is the function of eosinophils?
release cytoplasmic granules in response to multicellular parasites (like worms)
how do eosinophils begin their function?
they bind to PAMPs on worms to recognize antigen and then release granules to kill
are eosinophils common?
no; they only make up 2-4% of circulating WBCs
how do basophils work?
by binding to antigen-antibody complexes and releasing granules
what do basophils have receptors for?
antibodies
what is the major protein in the granules of basophils?
histamine
what does histamine from basophils do? (basophil function)
- makes blood vessel walls more permeable to allow recruitment of more immune cells to site of infection
- combat parasitic infections
what is the least common WBC, making up less than 1% of circulating WBCs?
basophils
what are basophils characterized by on a slide?
purple-staining granules
what is a side effect of histamine release?
allergy symptoms
what is the function of Mast Cells? (they’re copycats)
bind to antigen-antibody complexes and release histamine from cytoplasmic granules (copying basophils); also involved with parasitic infections
where are mast cells found?
in tissues! not circulation bc they are not a WBC!!
what are antigen-presenting cells (APCs)?
cells of innate immune response that bridge the gap between innate and adaptive immune response and activate T lymphocytes
are monocytes themselves APCs?
no; they mature into APCs
where are monocytes found?
travel in the bloodstream and then migrate into tissues to mature into macrophages
what do monocytes mature into? do they do much for immunity as monocytes?
macrophages; no
what are the 2 functions of macrophages?
- perform phagocytosis
2. process antigen and present it on cell surface (becoming APCs)
how do macrophages perform their function?
by binding to antibody-antigen complexes, enhancing phagocytosis
what is opsonization?
tagging an antigen for further elimination
what do antibodies serve as?
opsonins that mark antigen for immune cells
what are the 2 types of macrophages?
- tissue-specific macrophages
2. inflammatory macropages
what are tissue-specific macrophages?
long-term residents in tissues throughout the body that are NOT derived from monocytes
give 3 examples of tissue-specific macrophages
- osteoclasts
- microglia
- Kupffer cells
what are inflammatory macrophages?
derived from monocytes, enter tissue in response to infection
what are the 2 APCs?
- macrophages
2. dendritic cells
what are the 3 functions of dendritic cells?
- perform phagocytosis
- receptor-mediated endocytosis and pinocytosis
- process antigen and present on cell surface (becoming APCs)
where are dendritic cells found?
in tissues, NOT the bloodstream
what are the 3 major types of agranulocytes in the immune system?
- helper T cells
- cytotoxic T cells
- B lymphocytes
how are lymphocytes distinguished since they all look the same?
based on the proteins expressed on the cell surface
how are the surface proteins of lymphocytes named?
based on cluster of differentiation (CD) nomenclature
what is the CD nomenclature of helper T cells and what is their function?
- CD4+
2. activate other immune cells
what is the CD nomenclature of cytotoxic T cells and what is their function?
- CD8+
2. kill virally-infected cells
what do ALL T cells have? what is the function and result of that function?
a T Cell Receptor (TCR) that recognize antigen; are antigen specific and their binding action to antigen leads to clonal selection
what surface protein to B cells have?
B Cell Receptor (BCR)
what is BCR? function and result of that function?
B cell receptor; a non-soluble antibody attached to B cell surface that is antigen specific and its binding action to antigen results in clonal selection
what are plasma cells?
activated B cells!
do plasma cells have BCRs?
nope
what do plasma cells do?
secrete antibody that binds antigen for opsonization
are NK cells antigen specific?
nope; they are part of innate immunity
what do NK cells do?
attack and kill abnormal cells
what super cool thing can NK cells do that mimics adaptive immunity?
they can bind free antibody and coat themselves in pathogen-specific antibody so that when that antibody binds antigen, NK cells release cytotoxic material to kill the pathogen
what are primary lymphoid organs?
locations where immune cells develop and mature
what are the 3 primary lymphoid organs and what happens in each?
- Bone Marrow: B lymphocyte development in mammals
- Bursa of Fabricius: B lymphocyte development in BIRDS
- Thymus: T cell development in all animals
where is the Bursa of Fabricius located?
right off the cloaca
what happens to the Bursa of Fabricius after 6 months of age and what does this mean for birds?
it begins regressing so eventually birds have no way to replenish B lymphocyte supply
what are seconday lymphoid organs?
locations where the adaptive (lymphocyte) immune response is initiated
where is the innate immune response always inititated?
at the site of infection
what are the 3 secondary lymphoid organs?
- Lymph nodes
- spleen
- Mucosa-associated lymphoid tissue (MALT)
what happens in lymph nodes?
lymphocytes encounter antigen from local tissues
what happensin the spleen?
lymphocytes encounter antigen from the bloodstream
what happens in the MALTs?
activation of immune response at site of antigen entry
give 4 MALTs and their locations
- GALT: gastrointestinal
- NALT: nasal
- BALT: bronchi
- SALT: skin
what are tertiary lymphoid organs?
the site of infection; lymphocytes travel to this area to fight off infection
