Lecture 12 - B Lymphocytes II

Which cell is better at activating T-cells, B-cells or DCs?

B-cells have been shown to be better at activating T-cells than DCs

Mice models with no B-cells results in what?

Reduction in CD4+ T-cell activation

• Less antigen-specific CD4 T-cell expansion

Chimeric mice models with B-cells which have no APC function resulted in what?

Chimeric mice produced lower T-cell responses when stimulated.

• This is due to the lack of B-cell APC function

What happens if you remove CD80/86 (co-stimulatory molecules) from B-cells?

Was shown that these B-cells have no ability to activate T-cells

• And because of this, no T-cells could be activated

Anti-CD20 therapy was shown to be effective at treating RA. Why is this?

Anti-CD20 only kills B-cells and NOT plasma cells.

• This means anti-CD20 essentially removes APC B-cells

• This prevents activation of T-cells which causes a reduction in autoimmune responses

How do B-cells get antigens to present to T-cells?

B-cells are able to extract antigens off surfaces.

• Done via formation of an immune synapse with ‘antigen displaying’ cells

What are ‘antigen displaying’ cells?

Cell which can display antigens for B-cells to extract.

• These are NOT the same as APCs

Which types of cells can ‘display’ antigen to B-cells?

Both macrophages and DCs can display intact antigen on their surface

What does a B-cell do once it finds an antigen to process on a surface?

B-cell spreads out across the surface to collect antigens

• It rearranges its cytoskeleton in order to do this

How do B-cells differ from APCs?

• B-cells lead to more IFN-gamma production from activated T-cells

• B-cells produce a distinct cytokine profile when activated by different PRRs

  • These can have an effect on T-cell differentiation 

Why does removing B-cells ability to produce IL-6 reduce severity of MS?

Only IL-6 can now come from DCs

This means fewer Th17 cells and so less IL-17

• So a reduction in severity 

Fewer B-cells present in the body also seemed to cause worse severity of MS. Why is this?

Lack of B-cell derived IL-10 production which prevents recovery

• These B-cells are called B regulatory (Breg) cells.

What type of B-cell produces IL-10 to ‘turn off’ T-cell responses?

Breg cells

Which type of cell are Bregs derived from?

T2 B-cells

• Make IL-10