B and T Cell Co-operation NOT FINISHED Flashcards
What is the microscopic organisation of secondary lymphoid tissue essential for?
- bringing antigen-specific B and CD4 cells together to interact an produce high affinity antibody and develop memory
- other CD4 t helper subsets are primed here
Where are lymphocytes found in the body?
- main lymphoid organ is the spleen, 20% of lymphocytes, more in children
- MALT tissues or lymph nodes
To what do lymph provide a barrier?
- they form a barrier to the entry of organisms into the blood
It is important that we do not mount an immune response to commensal bacteria. How is this achieved?
subset of CD4 T cells that downregulate responses to communal bacteria, called regulatory T cells
- these also protect against autoimmunity
Why do we need Tregs if negative selection in the thymus gets rid of self-reactive cells?
- self-proteins can get modified by their environment and these can evoke an immune response
- ## Tregs abort immune responses to modified self
What areas is the spleen divided into?
red pulp and white pulp
What is the function of the red pulp?
red pulp = network of sinusoids where blood flow is slow, lined with macrophages (phagocytosis)
The efficiency of red pulp macrophage phagocytosis is vastly increased if the target is……
opsonised by antibody and complement
- this is where the white pulp comes in
What is the function of the white pulp?
- along with lymph nodes, white pulp allows B and T cells to collaborate to make antibodies
- B cells receive CD4 T cells, and then differentiate into plasma cells that produce antibody
- in primary responses these plasma cells move from white pulp to red pulp to opsonise pathogens for macrophages
When is a splenectomy used?
What are its consequences?
When autoantibodies are made: antibodies to RBC’s and platelets that cause anaemia and thrombocytopenia
- patients are susceptible to pneumococcal septicaemia
