Term
| What happens when a naive B cell encounters an antigen? |
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Definition
The cells proliferate (clonal expansion).
They then differentiate to generate a population of antibody secreting plasma cells and memory cells.
Some cells undergo affinity maturation, and some undergo class switching. |
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Term
| What is the antigen-independent phase of B cell development? |
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Definition
Maturation (happens in bone marrow).
Progenitor B cell has CD45r surface marker, it undergoes Ig-gene rearrangement and is turned into mature B cell. |
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Term
| What is the antigen-dependent phase of B cell development? |
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Definition
Activation and differentiation (happens in periphery)
Naive B cells come in contact with antigen, they either die, or become and activated B cell.
Activated B cells either undergo affinity maturation and become memory cells (which carry Ab on their surface), or undergo class switching and become plasma cells (secrete the Ab) |
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Term
| Where does antigen-dependent B cell development occur? |
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Definition
| Peripheral lymphoid organ. |
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Term
| Process of stem cell to B cell: |
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Definition
1. Lymphoid Stem Cell (BM)
2. Pro-B cell. (BM)
3. Pre-B cell. (BM)
4. Immature B cell. (BM)
5. Naive B cell. (Periphery)
6. Mature B cell. (Periphery) |
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Term
| Pro-B cells express what CD? |
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Definition
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Term
| What is required for a Pro-B cell to turn into a Pre-B cell? |
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Definition
Bone marrow stromal cells.
(And cytokines (IL-7) support the process) |
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Term
| How are heavy chains rearranged for Pro-B to Pre-B development? |
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Definition
| D-J joining, then V-DJ joining. Once this happens, the cell is classified as a Pre-B cells. |
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Term
| When Pro-B develops to Pre-B, what enzyme is expressed? |
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Definition
| TdT - terminal deoxyribonucleotidyl transferase. |
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Term
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Definition
| Catalyzes the insertion of N-nucleotides at the heavy chain coding joints. |
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Term
| What induces Pre-B cell maturation (from a Pro-B cell)? |
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Definition
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Term
| When a Pro-B cell is developing into a Pre-B cell, what stimulates IL-7 receptors? |
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Definition
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Term
| In the beginning of the Pro-B to Pre-B cell process, what does the Pro-B cell bind to? |
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Definition
| Stromal cell -- VLA-4 binds to VCAM-1. |
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Term
| What immunoglobulin is expressed on the surface of immature B cells? |
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Definition
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Term
| Description of a Naive B cell: |
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Definition
- Migrate out of the bone marrow.
- Quiescent - no dividing - G0
- Has not encountered antigen. |
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Term
| Description of mature B cell: |
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Definition
- Expression of IgM and IgD on surface.
- Cell division occurs. |
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Term
| Two types of B cell activation signals: |
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Definition
- With TI antigens.
- With TD antigens. |
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Term
| B cell signals with TI antigens: |
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Definition
| Signal 1 and Signal 2 both occur post-antigen binding without T helper cells. |
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Term
| B cell signals with TD antigens: |
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Definition
Signal 1: Antigen binding.
Signal 2: CD40 (B cell) binding to CD40L ligand (Th cell) |
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Term
| What 3 events occur in germinal centers? |
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Definition
- Affinity maturation.
- Class switching.
- Formation of plasma and memory cells. |
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Term
| When do germinal centers arise? |
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Definition
| 7-10 days after activation by TD antigen. |
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Term
| Class switching is dependent upon what? |
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Definition
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Term
| Affinity maturation requires what? |
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Definition
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Term
| Principle function of cell-mediated immunity: |
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Definition
| Response to intracellular pathogens, and cells expressing foreign antigens. |
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Term
| Antigen specific cells involved in cell-mediated immunity: |
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Definition
| Thelper-CD4 and Tcytotoxic-CD8. |
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Term
| Antigen non-specific cells involved in cell-mediated immunity: |
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Definition
| NK cells. Macrophages. Neutrophils. Eosinophils. |
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Term
| What are the primary events in CTL-mediated death? |
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Definition
- Conjugated formation.
- Membrane attack.
- CTL dissociation.
- Target cell destruction. |
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Term
| NK cells make up what percent of lymphocytes? |
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Definition
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Term
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Definition
Non-specific cytotoxicity.
No TCR/CD3.
Not MHC restricted.
No memory. |
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Term
| If a NK cell binds to a normal cell does it kill it? |
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Definition
| No because it expresses MHC class I - but it will kill a virus-infected cell, which does not express MHC class I. |
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Term
| What does ADCC stand for? |
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Definition
| Antibody-Dependent Cell-mediated Cytotoxicity. |
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Term
| What cells are involved in ADCC? |
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Definition
| NK cells. Macrophages. Neutrophils. |
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Term
| What do ADCC cells bind to? |
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Definition
| The Fc region of an antibody. |
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Term
| TCR gene expression is seen in what cells? |
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Definition
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Term
| What gene segments does Chromosome 14 posses? |
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Definition
Alpha-chain gene segments (V, J and C)
Delta-chain gene segments (V, D, J and C) |
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Term
| What gene segments does Chromosome 7 posses? |
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Definition
Beta-chain gene segments (V, D, J and C)
Gamma-chain gene segments (V, J and C) |
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Term
| Initial signal of T cell activation: |
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Definition
TCR-CD3 complex interacts with MHC-peptide complex.
Involvement of coreceptor.
- CD4 to MHC II
- CD8 to MHC I |
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Term
| Costimulatory signal of T cell activation: |
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Definition
| CD 28 to B7 (Th Cells/APCs) |
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Term
| Process of a stem cell development into T cells: |
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Definition
1. Hematopoietic stem cell (HSC) - Bone Marrow.
2. Common lymphoid precursor - Bone Marrow.
3. *Migration* - Blood.
4. T Cell Precursor - Thymus.
5. DN1 - Thymus.
6. DN2 - Thymus.
7. DN3 - Thymus.
8. DN4 - Thymus.
9. Double Positive (DP) - Thymus.
10. CD8+ or CD4+ - Thymus.
11. *Migration* - Blood.
12. CD8+ or CD4+ - Peripheral Tissues.
Alternative:
6. DN2 - Thymus.
7. Gamma-Delta T Cell - Thymus.
8. Gamma-Delta T Cell - Peripheral Tissues. |
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Term
| Thymic selection - Genetic rearrangement for generating TCR random or specific? |
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Definition
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Term
| Thymic selection processes (two) ensure that T cells have what two things? |
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Definition
Self-MHC restriction.
Self-tolerance. |
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Term
| Thymic Selection - Positive Selection Process: |
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Definition
- DP thymocytes interact with cortical epithelial cells
- Cells not capable of binding self-MHC die via apoptosis
- Cells that do bind become single positives(CD4 or CD8)
- Ensures self-MHC restriction |
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Term
| Thymic Selection - Negative Selection Process: |
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Definition
- Elimination of any CD4 or CD8 cells that have high affinity to self-MHC alone or to self MHC-self epitope complexes
- These cells are programmed to die (apoptosis)
- Ensures self-tolerance |
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Term
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Definition
- Bacterial or viral proteins capable of binding the TCR (V-beta domain) and MHC II.
- Induces non-specific T cell activation and proliferation leading to pathological effects. |
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Term
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Definition
- Inability of cells to proliferate in response to engagement with MHC-peptide complex.
- Due to absence of appropriate costimulatory signal or by CTLA-4. |
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Term
| Things that happen during T cell differentiation: |
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Definition
- It occurs in secondary lymphoid tissue.
- Activated cell becomes a blast cell.
- IL-2 levels are increased 100 times.
- Binds to IL-2 receptor on producing cell.
- Takesseveral days to occur.
- Effector cells and memory cells are produced. |
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