Antibodies
Antibodies are substances produced by the immune system to find and mark antigens, so that other substances can attack and kill them.

Antigens
Harmful substances, such as bacteria, viruses, toxins, cancer cells, blood or tissues from another person or species, that can cause disease or infection.

Autoimmune disease
Any one of more than eighty diseases caused by the immune system mistakenly attacking the body's own healthy cells, tissues, organs, and systems.   Among the autoimmune diseases are:

Autoimmune hemolytic anemia
An autoimmune disease in which antibodies attack and kill red blood cells.

Crohn's disease
An autoimmune gastrointestinal disease whose symptoms include persistent diarrhea, abdominal pain, fever, and general fatigue.

Grave's Disease
A thyroid condition that causes the gland to produce too much thyroid hormone.

Guillain-Barre Syndrome
An autoimmune illness that causes severe nerve damage. Two-thirds of all cases occur after a viral infection.

Hashimoto's Thryoiditis
An autoimmune disease, much more common in women than men, that affects the thyroid gland.

Inflammatory Bowel Disease
This term encompasses two small intestine disorders: Crohn's disease and ulcerative colitis.

Insulin-Dependent (Type 1) Diabetes
This disease causes the pancreas to produce too little insulin; it is more common in children and younger adults.

Multiple Sclerosis (MS)
A debilitating autoimmune disease that attacks the central nervous system leading to numbness, weakness, tingling, or even paralysis in one or more limbs.

Myasthenia Gravis
A chronic autoimmune disorder that leads to gradual muscle weakness; it often appears first in the face.

Psoriasis
A common skin disease caused by a speeding up of skin cell production, so that thick, scaly patches appear on the skin.

Rheumatoid Arthritis
This is the second most common form of arthritis (after osteoarthritis).  The immune system attacks and inflames the tissues of the joints, which creates pain, inflammation, swelling, and redness in joints.
 
Sjögren's Syndrome (Sjögren's disease)
This chronic but slowly progressing condition is an inability to produce tears or saliva. 

Systemic Lupus Erythematosus (SLE)
This is an inflammation of the body's connective tissues and can strike every organ.

Systemic Sclerosis (Scleroderma)
In this disease, immune cells create scar tissue in the skin, internal organs, and small blood vessels.

Ulcerative colitis
An inflammatory bowel disease whose symptoms include bloody diarrhea, pain, urgent bowel movements, joint pains, and skin lesions.

Vasculitis Syndromes
This term refers to a large group of diseases involving inflammation of and damage to blood vessels of any size, kind, or location.

COX-2 inhibitors
A type of non-steroidal anti-inflammatory drugs (NSAIDs) that have proven very effective in relieving pain; they do not cause gastrointestinal problems but have been associated with increasing the risk for heart attack and stroke.

CRP test
A blood test that measures the amount of C-reactive protein in the blood; a higher level of it suggests the presence of inflammation but does not tell where the inflammation is or what's causing it.

Immune cells
Various types of white blood cells that are part of the immune system and have specialized roles in the system's fight against infection and disease.

Immune system
The immune system is the body's natural defense system against infection and disease.  It consists of many organs and cells that have various specialized functions within the overall fight against antigens.

Infection
The disease state and symptoms caused by various harmful substances, such as bacteria and viruses, that have invaded the body.

Inflammation
One of the immune system's responses to the presence of antigens, caused by the antigen-fighting chemicals the system produces; inflammation is part of the disease fighting process but is characterized by with swelling, redness, warmth, and pain.

NSAIDs
Non-steroidal anti-inflammatory drugs, including non-prescription and prescription medicines, that combat pain and other symptoms of inflammation; prolonged use of them can cause gastrointestinal problems, such as ulcers.