Chapter 9 AI generated Flashcards
Describe the process of central tolerance induction in the thymus for T cells.
T cells enter the thymus from the bone marrow as immature cells, migrate to the cortex, rearrange TCR gene segments, undergo positive selection for MHC restriction and self-tolerance, become double-positive (DP) cells, and then proceed to negative selection in the medulla.
What is the role of cortical thymic epithelial cells in the thymus selection process?
Cortical thymic epithelial cells present MHC molecules loaded with peptides to immature T cells, testing them for MHC restriction and self-tolerance during positive selection.
Define positive selection in the context of thymic T cell development.
Positive selection is the process in the thymus where T cells that successfully recognize self MHC molecules and demonstrate self-tolerance are allowed to survive, while those that fail undergo apoptosis.
How do medullary thymic epithelial cells contribute to negative selection in the thymus?
Medullary thymic epithelial cells present self-antigens to T cells during negative selection, ensuring that T cells do not react against the body’s own antigens.
Describe the role of autophagy in the thymus selection process.
Autophagy is used by thymic epithelial cells to capture intracellular proteins and present them on MHC II molecules, expanding the range of self peptides presented to T cells for selection.
What is the significance of AIRE in thymic medullary epithelial cells?
AIRE drives the expression of tissue-specific antigens in medullary thymic epithelial cells, ensuring the presentation of a wide range of self-antigens to T cells during negative selection.
Describe the process of T selection in the thus.
In the thymus, T cells undergo positive selection (weak interaction), negative selection (strong interaction), or activation (strong interaction) based on their TCR engagement with MHC-peptide complexes.
What is the function of natural regulatory T cells (nTregs) in the immune system?
nTregs help suppress the activation of potentially self-reactive T cells by recognizing self antigens presented by APCs.
Define peripheral tolerance induction in the context of autoimmunity protection.
Peripheral tolerance induction ensures that T cells are anergized if they recognize self antigens without receiving co-stimulation, preventing them from causing harm.
How do B cells undergo tolerance induction in the bone marrow?
B cells in the bone marrow are tolerized by undergoing receptor editing if they recognize self antigens, and if unsuccessful, they undergo cell death.
Describe the role of NK cells in defending against viruses that downregulate MHC I molecules.
NK cells kill infected cells lacking MHC I molecules through a process known as ‘missing self,’ preventing viruses from evading immune detection.
What is the purpose of receptor editing in B cell development?
Receptor editing allows B cells to rearrange their receptors if they recognize self antigens during development in the bone marrow, providing them with another chance to avoid self-reactivity.
