Lecture 4 part 1- Adaptive immunity Flashcards
Describe the response initiated by innate immunity?
• Rapid response • PRR- germline-encoded • CD14 and mannose and scavenger Increased cytokine direct response-phagocytosis antimicrobial activity
Describe the adaptive response?
Slow recognition
initially low affinity for receptors- gene rearrangement and clonal expansion
Response- T and B cells with receptor encoded by fully rearranged genes
Memory
What is adaptive immunity orchestrated by?
Lymphocytes
what does the T cell all originate from?
Lymphoid progenitor
What are the four cells that are derived from lymphoid progenitor?
B-lymphocyte
Plasma cell
T lymphocyte
NK cell
Describe the T-Cell differentiation?
T-Cell precursor- Bone marrow
CD4+ and CD8+ - Thymus cortex- site of positive selection
CD4+ and CD8+- Thymus- Medulla site of negative selection
What does CD4+ form and where?
T- Helper cell
What does T-Helper cell form?
Th1
Th2
Th17
Treg
What does CD8+ form and where?
Cytotoxic T-cell
Both B cell and T cell development is guided by what and where?
stromal cells for B cell in the bone marrow
T-cell development compartmentalised- cortex and medulla of the thymus
Compare the production of B cell and T cells?
B cells are produced throughout life in the bone marrow
T cells are produced in the thymus which involutes at the end of puberty
Other than thymus, what other places generate new T cells?
Liver and intestine
How are the diverse repertoires of antigen receptors generated?
Genetic rearrangement
Describe the B cell stages of development?
1st step- the emergence of a pro-B cell
-Undergone genetic rearrangement of its diversity (D) and joining (J) segments.
2nd step: Differentiation to pre-B cells (large then small) and the
-First expression of a pre B cell receptor on the cell surface.
-Immature B cells then undergo a process of positive and negative selection – only those B cells that are positively selected and avoid negative selection are finally released into the peripheral blood.
Failure at either of these steps: apoptosis
Describe the T cell stages of development?
T cell precursors migrate to the thymus where they undergo four different stages of Double negative differentiation.(DN)
At DN stages CD4 nor CD8 are expressed
DN4 cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for CD4 and CD8. These cells, like immature B cells, undergo both positive and negative selection before being released into the peripheral blood as either CD4 or CD8 T cells.
