The immune system's primary role is to defend the body against harmful substances, including bacteria, viruses, and toxins.

Autoimmunity occurs when the immune system mistakenly recognizes and attacks its own body's tissues, leading to tissue damage and dysfunction.

T cells, particularly cytotoxic T cells, play a crucial role in recognizing and eliminating infected or cancerous cells, as well as foreign invaders.

B cells are responsible for producing antibodies, which are proteins that recognize and bind to specific antigens, marking them for destruction.

Cytokines are small proteins that act as messengers between immune cells, coordinating their actions and regulating the immune response.

Immune tolerance breakdown occurs when the immune system fails to distinguish between self and non-self, leading to the recognition of self-antigens as foreign and the initiation of an autoimmune response.

Rheumatoid arthritis is an autoimmune disease that causes chronic inflammation and damage to the joints, leading to pain, stiffness, and deformity.

Lupus is an autoimmune disease that primarily affects connective tissue, leading to inflammation and damage to various organs and tissues throughout the body.

Multiple sclerosis is an autoimmune disease that affects the central nervous system, causing inflammation and damage to the myelin sheath surrounding nerve cells, leading to a variety of neurological symptoms.

Type 1 diabetes is an autoimmune disease in which the immune system mistakenly attacks and destroys pancreatic beta cells, leading to a deficiency of insulin and an inability to regulate blood sugar levels.

Graves' disease is an autoimmune disease that causes an overactive thyroid gland, leading to increased thyroid hormone production and symptoms such as weight loss, anxiety, and heart palpitations.

Celiac disease is an autoimmune disease triggered by gluten proteins found in wheat, barley, and rye. The immune system mistakenly attacks the lining of the small intestine when gluten is consumed, leading to inflammation and damage.

Addison's disease is an autoimmune disease that affects the adrenal glands, leading to a deficiency of hormones such as cortisol and aldosterone, resulting in fatigue, weight loss, and low blood pressure.

Myasthenia gravis is an autoimmune disease that affects the neuromuscular junctions, where nerves connect to muscles. The immune system mistakenly attacks these junctions, leading to muscle weakness and fatigue.

Pemphigus vulgaris is an autoimmune disease that causes blistering and sores on the skin and mucous membranes due to the immune system attacking proteins that hold skin cells together.