Immuno Flashcards
Chemokine signaling? CXCL8?
- MAC produces IL-8
- Recruits neutrophils with CXCR1/2 (GPCRs); and basophils
- induces expression of proteins that help with cell entry
- induce lytic granule release
What pathway do cytokine activate?
JAK/STAT- JAK phosphorylates receptor –> STAT recruited, JAK phosphoryates STAT–> STAT dimerizes, goes to nucleus as TF
Defensins- types? and function of each?
part of innate immune system
Alpha defensin- neutrophils and paneth cells of intestine
Beta defensin- viral infection induces; prevents viral membrane fusion of non-infected cells
TLR types (5/10)? function?
Found on phagocytic cells and infected cells (induces IFNa/b) TLR4- recog LPS of gram neg bacteria TLR3- recog viral dsRNA TLR7/8- recog viral ssRNA TLR9- recog unmethylated CpG viral DNA
What cells work through respiratory bursts?
Phagocytic cells: MAC, DC, neutrophils
Role of mast cells?
Allergies/parasites
Histamine release
IgE binds via FcE receptor
Role of basophils
Rare, Allergic response
Cytokine release will impact T cell differentiation (IL-4)
Will bind IgE via FcE receptor
Eosinophils
Parasites
Cytotoxic cells?
NK and CD8+ T cells
% of each cell type
60% neutrophils
30% lymphocytes
<1% basophils
B cell function
Recognize free antigen w high specificity (antigen processing)
Received confirmation from T cell (B cell activation)
Proliferates and makes antibody (plasma)
Can also become memory cell
T cell function
CD4+
-Activation by APC presentation; highly specificity binding
-Express IL2 and IL2 receptor alpha –> proliferation and differentiation –> Th1,2,17,reg
CD8+: activation by infected cells; effector cells
How do T/B cells enter and leave lymph? Pathogens?
Naive T/B cells enter via bloodstream; leave via efferent lymphatics–> heart –> circulation
Pathogen enters with DC via afferent lymphatics
Complement enzymes are what kind of enzymes?
Serine proteases
How c3b opsonization –> phagocytosis?
CR1 on MAC binds c3b
Role of c3a and c5a
Recruit inflammatory cells (c5a help phagocytes adhere to endothelium and increase ability to phagocytosize)
Anaphylotoxins- contract smooth muscle, release histamine from basophil/mast cells, increase blood flow
Where does c3 come from?
Liver
Where is mannose found?
surface of fungi, bacteria, viruses
Describe lectin complement pathway complex? What does it do?
MASP (serine protease) + MBL (mannose binding lecctin)
Cleaves C4 and C2 to make classic C3 convertase (C2aC4b) (C4b embeds on pathogen surface)
How is classical pathway initiated?
CRP (c-reactive protein from liver acute phase response) or IgG/IgM (from Th1)
Bind PC of pathogen and C1; cleave C4 and C2 –> C2aC4b classic C3 convertase
How is alternative complement pathway inititated?
C3 spontaneous cleaves to iC3
Factor D cleaves Factor B –> iC3Bb (c3 convertase)
iC3Bb cleaves C3 –> C3a and C3b
Describe the convertases (4)
- iC3Bb- poor C3 convertase (alternative path)
- C3bBb- potent C3 convertase
- C3b2Bb- alternative C5 convertase (–> direct killing)
- C2aC4b- classic C3 convertase (classical and lectin path)
Review complement pathways
See notes
Cells in thymus? Function of each?
- Thymocytes- devo to T cells
- Epithelial cells (thymic stroma)- express MHC for positive selection; produces IL-7
- DC- negative selection (present self-peptide)
- MAC-clears dead lymphocytes
where do T cells devo?
Progenitor made in bone marrow
Differentiate/mature in thymus
what goes through VDJ rearrangement?
DJ pairs first!! then DJ-V
- beta chain of T cell- (first rearrangement);
Alpha chain goes to VJ pairing only - Heavy chain of B cell (first)
Light chain goes to VJ pairing only
Review T cell development
See notes
When does T cell express CD8/CD4?
After first chain rearrangement (beta)
“uncommittd double positive thymocyte”
Positive selection in T cell devo? in B cell devo?
T cell: select for T cells that can recognize MHC (off of stromal cells)
B cell devo: does not have positive selection
Differences between gamma chain and alpha/beta chain T cells?
Gamma chains do not require MHC presentation (positive selection); are mature after rearrangement
Gamma chains have less diverse receptors
what % comitted alpha/beta T cells will recognize MHC?
2%
When does T cell become single positive?
During positive selection; binding to MHCI–> CD8+, binding MCHII–> CD4+
Where does T cell positive selection occur?
cortex of thymus
Negative selection in T cell devo? In B cell devo?
T cell: DC presents self-antigen; strong binding –> apoptosis
B cell: same, remove cells that bind self
What is AIRE?
TF in thymus that promotes expression of all tissue types; negative selection during T cell devo
how does naive T cell enter lymph node?
CCR7 signaling
CCR7 from T cell binds CCL19/21 of stromal cell and DC of lymph tissue
where do B cells devo?
bone marrow
What is RAG1/RAG2?
involved in initiating rearrangement during B cell devo
What contributes to MHC diversity?
MHC-I: isotypes A, B, C, E, F, G (ABC are polymorphic)
(MHC-I has 3 heavy domain chains and 1 beta2 microglobulin)
MHC-II: isotypes DM, DO, DP, DQ, DR (PQR are polymorphic)
(MHC-II has alpha and beta chain only)
Genetics of HLA?
MHC diversity
Chromosome 6
2 alleles for each isotype (multiple isotypes of HLA make up a MHC) (ex. HLA-A1, A7, B….C…) then each serotype has additional heterogeneity)
hematopoiesis: where does it occur in each stage of devo?
first trimester, after first month: yolk sac
Second trimester: fetal liver/spleen
third trimester: bone marrow
EPO
erythropoietin (promote erythrocyte differentiation)
cytokine; type I short chain
