Basic immunology concepts Flashcards
C3bBb3b
Alternative C5 convertase
Alternative C3 convertase
C3bBb
Stimulates bone marrow
IL-3
Which two cell types posses granulysin, granzyme and perforin? What are their respective functions?
NK and CD8+ cells
Perforin - forms holes
Granzyme - protease, induces apoptosis
Granulysin - antimicrobial, induces apoptosis
Inhibited by IL-4 and IL-10
TH1
C4b2b3b
Classic C5 convertase
What is the function of TH2 cells?
Induce class switching to IgE and recruit eosinophils
What is the function of Tregs?
Maintain immune tolerance by suppressing CD4+ and CD8+ effector function
Stimulates growth of B cells vs. stimulates differentiation of B cells
Growth = IL-4
Differentiation = IL-5
Signal transduction for T cells
CD3
What does EBV bind to infect its cell?
EBV binds CD21+ on B cells
(but remember the big cells = CD8+ cells)
Surface marker of neutrophils
CD15+
(also Reed-Sternberg cells)
What are the two complement inhibitors and what is their main function?
C1 esterase inhibitor and DAF
Prevent complement activation of self cells
Binds LPS
CD14+ of macrophages and monocytes
Stimulates T cells
IL-2
Where does positive seletion occur and what is its purpose?
Cortex
T cells capable of binding self-antigen are selected to survive
How can Tregs be identified?
CD3+, CD4+, CD25+, FOXP3 transcription factor
Alternative C5 convertase
C3bBb3b
Fever
IL-1, IL-6
TH2 cells develop under influence of which cytokine?
IL-4
C4b2b
Classical C3 convertase
Secreted by macrophages to activate NK cells and induce differentiation into TH1 cells
IL-12
What is the function of IF alpha and beta?
Released by virally-infected cells to prime neraby cells for infection
Which occurs first: + or - selection?
+
Binds Cd3
CD21+ of B cells
Which cytokines are released by TH2 cells?
!L-4. IL-5, !L-6, IL-10, IL-13
C3bBb
Alternative C3 convertase
CD4+ exposed to IL-12
TH1
Classical C3 convertase
C4b2b
What occurs when a virus enters a cell that has been primed by IF alpha +/- beta from a nearby cell?
The viral RNA polymerase activates RNase, which cleaves viral and host mRNA, and protein kinase, which prevents viral and host protein synthesis, effectively causing apoptosis of the cell to prevent viral spread
Activates osteoclasts
IL-1
All surface markers on NK cells
CD16, CD56
All surface markers on macrophages
CD14, CD40, B7, MHC class II, Fc and C3b receptor
CD15+
Neutrophils and Reed-Sternberg cells
Increases MHC expression and antigen presentation by all cells
IFgamma from TH1 cells
Tregs develop under influence of which cytokines?
TGFß
Mediates septic shock
TNFalpha
Where does negative selection occur and what is it’s purpose?
Medulla (M = N)
T cells with high affinity for self-antigen are selected to undergo apoptosis
FOXP3 transcription factor
Tregs
Promotes growth and differentiation of eosinophils
IL-5
(although IL-4 stimulates class switching to IgE)
What does LPS bind to stimulate immunity?
CD14 on macrophages/monocytes
(Remember: LPS is not a protein, so it is a thymus-indepedent antigen = T cells not involved)
CD14+
Macrophages and monocytes (binds LPS)
All surface markers on a killer T cell
CD8, CD3, CD28
Surface marker of macrophages and monocytes
CD14+
Describe the interaction between TH1 cells and macrophages
Macrophages release IL-12 which stimulates differentiation into TH1 cells, which in turn secrete IFgamma, which activates macrophages
Two roles of C3b
Opsonization
Clearing immune complexes
TH2 cell secretes IL-5. What happens to B cell?
Class switching to IgA
Activates production of acute phase reactants
IL-6
What is the signal for ADCC?
CD16 binds to Fc portion of IgG on cell to be killed; NK cell releases granzyme and perforin
What is the function of TH1 cells?
Activate macrophages and CD8+ cells
Two primary opsonins
IgG and C3b
TH17 cells develop under influence of which cytokines?
!L-6 and TGFß
CD19+/CD20+/CD21+
Mature B cell (see in CLL)
CD3+ CD4+ CD25+
Tregs
Which cytokine functions similarly to GM-CSF?
IL-3 (Activates bone marrow)
Cytokines secreted by macrophaes
IL-1, IL-6, IL-12, TNFalpha
Secretes IFgamma
TH1
Tdt+
Pre-B and pre-T cells (see in ALL)
TH1 develops under influence of which cytokine?
IL-12
CD4+ exposed to !L-6 and TGFß
TH17
Steps in the lectin complement pathway
MBL binds mannose on microbial surfaces –> activates a C1-like complex –> cleaves C4 into C4a and C4b –> C4b joins C2b from the classical pathway –> classical C3 convertase C4b2b formed –> cleaves C3 into C3a and C3b –> C3b joins to form classical C5 convertase C4b2b3b –> cleaves C5 into C5a which is a PMN recruiter and C5b –> C5b joins C6-9 to form MAC –> cytotoxicity and lysis
CD10+
Pre-B cell (see in ALL)
What happens after T cells undergo negative selection in the thymus?
They move to the bone marrow where CD4+ cells differentiate
What are the three signals needed for B cell activation and subsequent class switching?
- B cell receptor-mediated endocytosis of antigen with presentation on MHC class II recognized by TH cell
- CD40 on B cell binds CD40L on TH cell
- TH cell secretes cytokines that determine class switching
What is the function of each cytokine secreted by TH2 cells?
!L-4 = IgE and IgG class switching
IL-5 = IgA class switching
IL-6 = stimulates acute phase reactant production
IL-10 = inhibit TH1 differentiation
IL-13 = allergic and parasitic responses
Activates NK cells
IL-12
Causes vascular leak
TNFalpha
What two signals are needed for T cell activation?
- Antigen presentation by an APC (B cell, MØ, dendritic cell) on MHC class I or class II
- B7 on APC binds CD28+ on T cell = co-stimulatory signal
Which cytokines are released by TH1 cells?
IFgamma
Which cytokines inhibit differentiation into TH1 cells?
IL-4, IL-10 from TH2 cells
Surface markers of mature B cell
CD19+/CD20+/CD21+
TH2 cell secretes IL-4. What happens to B cell?
Class switching to IgE and IgG
Classic C5 convertase
C4b2b3b
Which cytokines are produced by Tregs?
IL-10 and TGFß (anti-inflammatory)
Steps in the classical complement pathway
C1 binds IgG or IgM Fc region –> C1 complex cleaves C2 into C2a and C2b –> C2b joins C4b from lectin pathway –> classical C3 convertase C4b2b formed –> cleaves C3 into C3a and C3b –> C3b joins to form classical C5 convertase C4b2b3b –> cleaves C5 into C5a and C5b –> C5b joins C6-9 to form MAC –> cytotoxicity, lysis
Steps in alternative complement pathway
Microbial surface or spontaneous activation causes C3 to cleave into C3a and C3b –> C3b joins with Bb (B is cleaved via D) –> alternative C3 converstase C3bBb is formed –> cleaves more C3 –> C3b joins C3 convertase to form C5 convertase C3bBb3b –> cleaves 5 into 5a which recruits PMNS and 5b –> 5b joins 6-9 –> MAC formed –> lysis, cytotoxicity
All cell surface markers on helper T cell
CD4, CD3, CD28, CD40L
All surface markers on B cells
CD19, CD20, CD21, CD40, Ig, MHC II, B7
Which two cytokines are secreted by all T cells?
IL-2 and IL-3
Inhibited by IFgamma
TH2
Activates adhesion molecule expression on endothelium
IL-1
CD4+ exposed to TGFß only
Tregs
CD4+ exposed to IL-4
TH2
Secretes IL-4, IL-5, IL-6, IL-10, IL-13
TH2
Secretes IL-10 and TGFß
Tregs
Surface marker when T cell enters thymus
CD4+CD8+
