Lymph node development Flashcards
Of what cells do lymph nodes arrive?
Stromal cells and Lymphoid Tissue Inducer (Lti) cells.
Which TNF receptors are essential for lymphoid organ formation?
Lymphotoxinα1β2 and LTβR
How do lymphoid organs form?
Lti cells express LTαβ on the cell surface, stromal cells have LTβR receptors and when activated the stromal cells make chemokines and adhesion molecules. Chemokines attract other cells, adhesion molecules helps cells stay at their place.
What is the function of CXCL13?
It regulates attraction of Lti cells to the forming lymphnodes.
How is Retinoic acid produced?
Retinol (vitamin A) is broken down bij RALDH, which is expressed in nerve fibers, into retinoic acid and binds receptors in nucleus and will turn into transcription factor.
What is the function of Retinoic acid?
It induces CXCL13 production and is important in cell differentiation and proliferation.
Which stromal cell subset is present in the B-cell follicles?
Follicular Dendritic Cells (FDC).
Which stromal cell subset is present in the T-cell areas?
Fibroblastic Reticular Cells (FRC).
Which stromal cell subsets can express self-antigens and are involved in control of autoreactivity?
Blood Endothelial Cells (BEC), Lymphatic Endothelial Cells (LEC) and Fibroblastic Reticular Cells (FRC).
How is central tolerance in the tymus regulated?
Negative selection by T-cells (high TCR affinity for self-antigen results in apoptosis) and regulation by Treg induction which produce IL-2 (lower TCR affinity for self-antigen).
Which cells express self-antigens in the thymus?
Medullary Thymic Epithelial Cells (mTECs).
How is peripheral tolerance in the lymph nodes regulated?
With low expression of self-antigen in MHC class I CD8 T cells will be deleted. expression of self-antigen In MHC class II results in CD4 T cells anergy, apoptosis or Treg maintenance specific for the self-antigens.
Which cells express self-antigens in the lymp nodes?
Lymph node stromal cells.
What is the function of MHCII on stromal cells?
lymph nodes stromal cells maintain Treg cells with MHCII; self-antigen presentation in MHCII by LN stromal cells converts Tn cells into Treg cells.
