Lymphoid tissues Flashcards
What are the hallmarks of adaptive immunity
Specificity - unique T and B cells Memory - rapid expansion
What is somatic hypermutation
Where activation-induced cytidine deaminase makes random mutations which results in an antibody being able to better bind to the target
What are examples of T cell receptors
TCRA and TCRB which encode for heterodimeric TCRap
What are the primary lymphoid organs
Blood marrow Thymus Foetal liver
Where is the bone marrow production restricted to
Flat bones Long bones
Diagram of bone marrow
Where is the final maturation of B cell occurs
Periphary
Where is the thymus located
Above the heart
White highly structured tissue
Highly organised
How do T cells undergo development
Positive selection - Can see MHC on surrounding cells
Negative selection - Large signal from the TCR from own antigens, undergoes apoptosis
How does thymus develop with age
Output declines
Replaced by fat tissue
Declining ability to generate immune response
Secondary lymphoid organs
Mature lymphocytes interact with other antigens
Spleen
Lymph nodes
Appendix
Mucosal associated GI
Lymphoid tissue
Some lymphoid tissue locations
Generally highly organised structures
Normally discrete organs
Structure of lymph nodes
Have a tough capsule
Surrounded by specialised fatty deposits
Cortex - outer layer - b cell area and follicle area
Paracortex - middle layer - T cells and dentritic cells
Structure of the spleen
Why is lymphatic systems strong in external areas
To drain and take away the antigen to prime it for immune response
What are the lymphoid tissues in gut called
Peyer’s patches
Contains high number B cells
What is the germinal centre
Anatomically restricted site where B cells undergo mutation and selection
Structure of tonsils
How do antigens get to the T and B cells
Drainage absorbed into the lymph
Where do naive T cells go
Recirculate once every 24 hrs
What are some new immunotherapies
CAR-T
Ipilmumab
Nivolumab
anti-CTLA4
anti-PD1
How to naive T cells get into the lymph nodes
How do the antigen get transferred ot the secondary lymphoid tissues
Uptake by antigen presenting cells - dendrites
Migrate towards T and B cells
Some of the antigen molecules will be in the blood
What is the definition of antigen presentation
Display of peptides in the major histocompatibility complex 1 or 2 proteins such that the T cells can attempt to bind them
What does the conduit system do
It increases the chances that a T cell and dentrite cell will meet up
