Immune tolerance is the ability of the immune system to ignore harmless antigens while attacking harmful ones.
Why is immune tolerance important for the immune system?
It prevents the immune system from attacking the body's own healthy cells, reducing the risk of autoimmune diseases.
What can happen if immune tolerance fails?
The immune system may attack healthy, uninfected cells, leading to autoimmune diseases.
In the football analogy, what does the quarterback represent?
The quarterback represents the immune system.
According to the football analogy, what do the teammates and opponents represent?
Teammates represent harmless antigens, and opponents represent harmful antigens.
What are the two main types of immune tolerance mechanisms?
The two main types are central immune tolerance and peripheral immune tolerance.
Where does central immune tolerance occur for T cells and B cells?
Central immune tolerance occurs in the thymus for T cells and in the bone marrow for B cells.
What process is involved in central immune tolerance?
Central immune tolerance involves negative selection, which eliminates self-reacting T and B cells before they leave the primary lymphoid organs.
What is the main function of peripheral immune tolerance?
Peripheral immune tolerance eliminates or inactivates self-reacting T and B cells that escaped central tolerance, using both negative and positive selection.
What is negative selection in immune tolerance?
Negative selection is the process of eliminating immune cells that react to self or harmless antigens, usually through apoptosis.
What is positive selection in immune tolerance?
Positive selection promotes the survival of immune cells that can appropriately bind to MHC molecules.
What happens to T and B cells that bind to harmless antigens during negative selection?
They are eliminated through apoptosis to prevent them from attacking the body's own tissues.
Approximately what percentage of T and B cells survive both central and peripheral tolerance mechanisms?
Only about 5% of T and B cells survive; the remaining 95% undergo apoptosis.
What does it mean for a T or B cell to become anergic?
An anergic cell is unresponsive and eventually undergoes apoptosis, preventing it from causing harm.
Why are the T and B cells that survive tolerance mechanisms considered effective?
They are effective because they can target harmful antigens without attacking harmless or self-antigens.