3/30/17 TEST #3 B cell-mediated immunity GERMAN Flashcards
If you can not form T cell immune synapses, which of the following immune functions would you anticipate to be disrupted? A) T cell activation B) B cell activation C) CD8 T cell targeting D) All of the above E) None of the above
- D) All of the above
- Because the B cell is activated by TFH cells and the others are T cells that need immune synapses to be activated
After you have positive selection with B cells what are the next three steps of B cells?
- Search for infection
- Finding infection
- Attacking infection
Where in the body to B cells find infection and become activated?
-Secondary lymphoid tissues
What two types of effector cells do B cells become?
- Memory Cells
- Plasma cells
B cells mature within and migrate through what types of tissues?
-Secondary lymphoid tissues
B cells are presented antigen where?
-In lymph nodes
What do the follicular dendritic cells and the macrophages do with intact antigens?
-Capture them and present them in the B cell areas in the lymphoid tissue
What does activation of B cells drive?
-Clonal expansion
-Class switching
-Somatic hypermutation
(These processes require T cells)
What presents antigen to B cells coming into the lymphoid tissue?
- Macrophages
- Follicular Dendritic cells
What are stromal cells involved in B cell development and activation?
-Follicular dendritic cells
Do follicular dendritic cells have phagocytic activity?
-No
How do follicular dendritic cells accumulate antigens?
-Via complement receptors
What are the two antigen types that can activate B cells?
- Thymus-dependent antigen
- Thymus-independent antigen
What three things are involved with thymus-dependent antigens to activate B cells?
- Protein
- Protein associated antigen
- TFH cell interaction required
What two things are involved with thymus-independent antigen to activate B cells?
- PRR-detected antigen
- Complement-bound antigen
What are three signals needed for B cell activation?
- Antibody Crosslinking
- Co-receptor signaling
- Cytokines
What does antibody crosslinking do for B cells?
-Activation
What does co-receptor signaling do for B cells?
-Survival and proliferation
What do cytokines do for B cells in activation?
- Differentiation
- Class switching
- SHM (Somatic Hypermutation)
What does crosslinking of B cells involve?
- B cell receptor
- Antigen
How does the B cell know that the antibody is bound to an antigen?
- You get clustering and aggregation
- Iga and Igbeta signaling
- ITAM phosphorylation and signal recruitment
How does the B cell ensure that the antigen is pathogenic?
- Co-receptors
What prevents anergy in B cells?
-Co-receptor signaling
What allows the B cell to distinguish between foreign or self antigen?
-Co-receptor signaling
If a B cell binds a pathogen but doesn’t bind a co-receptor signal what type of pathogen is it?
-Self antigen
What initiates clonal expansion for B cells?
-Co-receptor signaling
What are B cell co-receptor complex molecules?
- CR2
- CD19
- CD81
- Complement
What cells are the most common source of cytokines during B cell activation?
-TFH
What provides signals in the absence of T cell-mediated activation?
-Local cytokines
What does somatic hypermutation due for antibodies?
-Increase antibody speficficity
Once B cells are differentiated what do they become?
- Plasma cells
- Memory B cells
What drives B cells activation, proliferation, enhanced specificity, and differentiation into plasma and memory cells?
-TFH
TFH activation of B cells typically yields a larger population of what types of cels?
- Plasma cells
- Memory B cells
What does CD40 induce for B cells?
-Survival and proliferation
Where does isotype switching primarily occur at?
-Germinal centers
T/F B cells can present antigen to TFH cells
True
What type of antibody does the cognate pair form during the primary focus?
-IgM (To prevent pathogens from moving systemically)
When cognate pairs move to the secondary focus what do they form?
-Germinal centers
Does primary or secondary focus allow class switching and somatic hypermutation?
-Secondary focus
What do cognate pairs first form?
-Centroblasts
What do centroblasts create?
-Centrocytes
Do centroblasts or centrocytes do class switching?
-Centroblasts
Do centroblasts or centrocytes form the light zone in germinal centers?
-Centrocytes
T/F Both centroblasts and centrocytes can do somatic hypermutation
False
-Only centroblasts
What improves antibody specificity ?
-Class switching and Somatic hypermutation
What antibody regions changes in class switching?
-Fc region of heavy chain
T/F Class switching is cytokine induced
True
T/F Somatic hypermutation produces new epitope binding regions
True
What increases antibody affinity?
-Somatic Hypermutation
What do follicular dendritic cells select for?
-High-affinity centrocytes
What have centrocytes undergone?
-First round of somatic hypermutation
Only centrocytes that bind what can bind TFH cells?
-FDC (follicular dendritic cells)
What are FDC-bound centrocytes bound by?
-TFH cells
WHEN FDC bound centrocytes are bound by TFH cells you will get a survival signal and have the selection of centrocytes with the highest what?
-Antibody affinity
Once a B cell goes from a centrocyte it can become a plasma cell or a memory cells, once it becomes a plasma cell can it class switch?
-No
When you have a B cell activation it requires three signals, what are they?
- IgD antigen binding
- Co-receptor signaling
- Cytokine
Thymus independent activation of B cells leads to what type of cells?
-Plasma cells
What is the cognate pair?
-B and TFH cell
Where does the primary focus of the cognate pair occur ?
-Medulla to release IgM plasma cells
What step of B cell activation deals with FDC selection, Proliferation, and Differentiation?
-Centrocytes
What three antibodies deal with internal tissues?
- IgM
- IgG
- IgA
What antibody deals with mucosal surfaces?
-IgA
What antibody deals with parasite immunity?
-IgE
What antibody deals with B cell receptors?
-IgD
What type of receptors bind antibodies and provide adaptive specificity to innate cells?
-Fc Receptors
Fc receptors allow adaptive immunity to enhance what cells specificity and function?
-Innate immune cell
T/F Fc Receptors often require dimerization
True
What facilitates IgG transport into tissues?
-Fc Receptors
What does trancytosis of IgA protect?
-Mucosal surfaces
What do neutralizing antibodies prevent?
-Pathogen Establishment
What are two neutralizing antibodies?
- IgA
- IgG
What clears agglutinized antigens?
-Erythrocytes
What does opsonization lead to?
-Phagocytosis
What three cells does IgE make competent?
- Basophils
- Mast cells
- Eosinophils
What two antibodies initiate the complement classical pathway?
- IgM
- IgG
T/F Antibodies provide passive immunity during development
True
What antibody is involved in passive immunity during gestation?
-IgG
What antibody protects infant mucosal surfaces?
-IgA