Thymic selection

Thymic selection is a process in the immune system that produces T cells. It occurs in the thymus, an organ located in the chest, which is responsible for the production of T cells, a type of white blood cell. Thymic selection is a crucial part of the immune response, as it ensures that the body produces T cells that can recognize and respond to foreign substances, while eliminating those that might attack the body's own cells.

Process

Thymic selection involves two main stages: positive selection and negative selection.

Positive selection occurs first. During this stage, immature T cells, or thymocytes, that are capable of recognizing Major Histocompatibility Complex (MHC) molecules are selected for survival. MHC molecules are proteins found on the surface of all body cells and are crucial for the immune response. Thymocytes that cannot recognize MHC molecules are eliminated through a process called apoptosis, or programmed cell death.

Following positive selection, thymocytes undergo negative selection. In this stage, thymocytes that strongly react with the body's own proteins, or self-antigens, are eliminated. This process ensures that T cells do not attack the body's own cells, preventing autoimmune diseases.

Significance

Thymic selection is crucial for the proper functioning of the immune system. By ensuring that T cells can recognize foreign substances and eliminating those that might attack the body's own cells, thymic selection helps to maintain the body's immune balance and prevent autoimmune diseases.

See also

• Immune system
• T cell
• Thymus
• Major Histocompatibility Complex
• Autoimmune diseases