T1 L4: Adaptive immunity Flashcards
What is the immunophenotype of a B-cell?
They express CD19 and CD20
What is the immunophenotype of T-cells?
They express CD3 and either CD4 (T helper) or CD8 (Cytotoxic T cell)
How do B-cells mature?
They are created in the bone marrow where they continue to differentiate by negative and positive differentiation
What is negative differentiation?
When self-antigens bind to the B or T-cell receptor which causes apoptosis of the cell
How do T-cells mature?
They are created in the bone marrow. The T-cell progenitor cells will then migrate to the thymus and continue to differentiate by positive and negative differentiation
How do T-cells mature?
They are created in the bone marrow and then the T-cell progenitor cells will migrate to the thymus and continue to differentiate by positive and negative differentiation
What are the antigens for B-cells?
B-cell receptor (BCR) or T-cell receptor
They can recognise native antigen present on micro-organisms
The recognise only specific antigens
What are the antigens for T-cells?
MHC-bound peptides
They need antigens that have been processed into peptides and presented
What do CD4 T-cells recognise?
MHC-II
What do CD-8 T-cells recognise?
MHC-I
Why do B-cells need T-cell to activate an immune response?
They can’t induce antibody production without it
They are thymus dependent
What are thymus dependent antigens?
Proteins that depend on Helper T-cells to induce antibody production
What are Thymus independent antigens?
Polysaccharides and lipids that don’t need Help T-cells to induce antibody production
What are some properties of T-cell independent responces?
- Involve simple, repetitive antigens, mostly IgM
- Modest affinity
- No memory
What are the 3 activation signals for B-cells?
- Binding to an antigen presenting cell
- Reinforcement following binding of CD40L on T-cell and CD40 on B-cell
- T-cell secretes cytokines that further signal to the B-cell
