What's the learning goal?
You will understand the role of the central and peripheral lymphoid tissues in generating and maintaining the adaptive immune system.
Central lymphoid tissues (name 2)
- bone marrow
Peripheral lymphoid tissue (name 4)
Unlike T-cells which migrate from bone marrow to thymus for development, B-cells
stay put and mature in the bone marrow
What cells are critical for B-cell development in bone marrow
stromal cells in bone marrow
Each lymphocyte recognizes
only 1 type of antigen, & if it proliferates, all subsequent lymphocytes will be a clone of the first one.
Adaptive immunity occurs if
the lymphocyte meets its corresponding antigen in the peripheral lymphoid tissue.
lymphocytes and lymph return to blood via
The final stages of development of immature B cells into mature B cells occur in
the peripheral lymphoid organs
Early stem cells reside in the ________ just below the inner cavity of the long bones, but then move toward ________ cells in the trabeculae
What maturation factors do stromal cells secrete, that promote B-cell development in the trabeculae?
Central Tolerance: immature B cells in the BM are tested for
reactivity to self antigens, or autoreactivity, and are eliminated if autoreactive.
4 possible fates of B-cells, during central tolerance screening?
1. No self-reaction - migrates to periphery
2. Multivalent self-molecule - apoptosis or receptor editing
3. Cross-linking receptors to soluble self-molecule: anergy
4. Low-affinity, non-cross linking: clonal ignorant (may cause auto-immunity)