innate immunity Flashcards
1
Q
physical and physiological barriers of the innate immune system
A
- intact skin and mucous membranes
- ciliated cells in the respiratory tract (ciliary elevator)
- hydrolytic enzymes in secretions (like saliva)
- low pH (skin, stomach, vagina)
- fluid flow (in bladder and heart)
- defensins (GI and respiratory tracts)
- normal flora occupies receptors and prevents pathogen colonizations
2
Q
WBCs of innate immunity
A
- neutrophils
- monocytes and MΦ
- basophils and mast cells
- NK cells
- eosinophils
3
Q
neutrophil function (aka granulocytes, PMNs, bands)
A
- mobilize quickly from the bone marrow to blood/tissue
- phagocytose and kill micro-organisms
- release cytokines
- do not present antigen on MHC class II
- major cell of acute inflammatory response
4
Q
monocyte and macrophage function
A
- monocytes in blood; macrophages in tissues
- recognize patterns on pathogens and release cytokines
- phagocytose
- APCs (MHC class II)
5
Q
basophil and mast cell function
A
- basophils in blood; mast cells in tissues
- express TLRs that recognize bacteria and virus patterns
- activated by tissue damage, C3a and C5a complement, and IgE binding
- rapidly release mediators of inflammation (histamine)
6
Q
NK cell function
A
- recognize absence of MHC class I (tumor cells and infected cells lack MHC class I)
- contain and secrete cytotoxic granules to directly kill infected cells
- don’t express antigen specific receptors
7
Q
complement function
A
- plasma proteins that augment (complement) inflammation)
- directly lyse cells
- opsonization
8
Q
why must complement be activated and what are the 3 pathways for activation?
A
- complement circulates as inactive precursors => must generate C3 convertase to cleave C3 into active subparts
- pathways: classic, alternate, lectin
9
Q
classic pathway
A
C1 binds constant fragment of antigen bound IgG or IgM
10
Q
alternative pathway
A
microbial products directly activate complement
11
Q
lectin pathway
A
mannose-binding lectin binds carbohydrate antigens on the surface of micro-organisms (such as encapsulated bugs)
12
Q
what complement proteins are made after activation of C3 convertase?
A
- C3 => C3a and C3b
- C3b => C5
- C5 => C5b and C5a
13
Q
how do bacterial capsules help bugs evade immunity?
A
prevent complement activation and decrease C3b (opsonin) binding
14
Q
defensins
A
- highly cationic peptides
- create pores in bacterial membranes
- GI tract = alpha; respiratory tract = beta
15
Q
interferons (alpha and beta)
A
- antiviral proteins
- bind to cell and induce anti-viral state (inhibit replication)
- produced by lymphocytes and mΦ
