Final answer:
If the T cell receptor binds to self-antigens, apoptosis is initiated to eliminate potentially harmful cells. This process ensures that only T cells capable of recognizing foreign antigens, not the body's own tissues, survive.
Step-by-step explanation:
If the T cell receptor binds tightly, a signal is released that induces apoptosis. In other words, those cells that recognize self-antigens from one's own body are destroyed. This process is essential for the immune system to prevent attacking its own cells, which can lead to autoimmune diseases.
During T cell development, immature T cells undergo a selection process where they are tested for their ability to distinguish between self and non-self proteins. This occurs in the thymus through negative selection wherein T cells that tightly bind to self-antigens presented by professional antigen-presenting cells are induced to undergo apoptosis. Those that do not bind tightly to self-antigens survive to become mature T cells that can respond to foreign antigens.
Some T cells express either the CD4 or the CD8 receptor, but not both. T cells expressing the CD4 receptor become helper T cells (TH), while those with CD8 become cytotoxic T cells (Tc). These mature T cells play crucial roles in the immune response by targeting and destroying foreign pathogens.