Question

Self tolerance in T lymphocytes is initially induced mainly within the thymus in fetal and perinatal life by a process of clonal selection (negative selection) and deletion of self-reactive immature T cells, presumably initiated by reaction of their receptors with self antigen complexed with self MHC molecules. Most of thymic T cells die within the thymus, reflecting negative selection by a natural process of programmed cell death called apoptosis. What mediates apoptosis of self-reactive T cells in the perinatal thymus?

Fas
CEA
AFP
MAGE
Ras

Answer 1

During negative selection in the thymus, apoptosis is used to eliminate self-reactive T cells that bind with self-antigens, ensuring the survival of only those T cells that recognize foreign antigens presented by MHC molecules, thereby maintaining immune self-tolerance and preventing autoimmune diseases.

Step-by-step explanation:

Understanding Apoptosis of Self-Reactive T Cells in the Thymus

Apoptosis, or programmed cell death, mediates the elimination of self-reactive T cells during the negative selection process in the thymus.

This mechanism ensures that only T cells which can bind to MHC molecules with foreign antigens presented on their clefts survive, preventing autoimmunity.

Self-reactive T cells that react with self-antigen presented by antigen-presenting cells (APCs) undergo apoptosis.

This process is part of what is referred to as central tolerance, a critical step in the development of a functional immune system that avoids attacking the body's own tissues.

In summary, negative selection in the thymus filters out T cells that are reactive to self-antigens, utilizing apoptosis to prevent the potential development of autoimmune diseases.

These self-reactive T cells are deleted in a natural process of programmed cell death, ensuring immune self-tolerance.