Chapter 4 Flashcards
Adaptive Immunity
Specific response
Memory of prior exposure
enhanced response to pathogen upon repeated exposure
Slower than innate, but longer lasting
Where do T cells mature
Thymus
T Cell Differentiation: Double Negative
Chemokines push T-cell precursors to thymus
Thymocytes lack CD4 and CD8 markers
Gene rearrangement codes beta chain for T-cell receptor (TCR)
Unique antigen binding site created
CD3/TCR complex
CD3/TCR Complex
The T-Cell receptor for antigen. The alpha and beta chains have a variable region that binds to a specific antigen
Two types of adaptive immunity and their related cells
Cell Mediated - T cells
Humoral- B cells and plasma cells
T Cell Differentiation: Double Positive
Thymocytes express CD4 and CD8
Positive Selection - survival if TCR recognizes MHC
Negative Selection - those that fail PS are destroyed by apoptosis
T-Cell Differentiation: Single Positive
Only the cells that are positive for CD4 and CD8
Negative selection - Thymocytes that bind to self antigens on thymic stromal cells undergo apoptosis
T-Cell Differentiation: Mature T cell
Survivors of the last 3 stages of differentiation (DN, DP, SP) exit the thymus and recirculate between the blood and lymphatics
CD4 T-cells
T helper and T regulatory
CD8 T Cells
Cytotoxic T cells
Where does B cell Differentiation take place?
Bone marrow
B Cell Differentiation: Pro-B cells
Rearrangement of genes that code for heavy and light chains of antibody molecules
Variable region of specificity
Cells must successfully rearrange one set of heavy-chain genes to move on to pre-B Cells
B cell Differentiation: Pre B Cell
Heavy u chains of IgM class accumulate in cytoplasm
B-Cell Differentiation:
Immature B Cells
Pre-BCR is replaced with functional BCR
B Cells that have receptors for self-antigens are deleted
Surface proteins: CD21, CD40, Class ii MHC
B-Cell Differentiation: Mature B cell
Do not react with self-antigens
Display appropriate surface markers
migrate to the spleen for further development
Cell Surface: IgM and IgD
