Antibodies are Y-shaped proteins on the surface of B lymphocyte cells that are used by the immune system to fight pathogens. Peptide antibodies are specifically made by the body to combat the unusual forms of peptides made by diseased body cells or pathogens. The presence of certain types of peptides in cells causes peptide antibodies to be sent to eliminate them. Research scientists use peptide antibodies to detect and identify diseases such as rheumatoid arthritis.
Citrulline antibodies are peptide antibodies that are sent to attack the amino acid citrulline in circular or ring-shaped peptides. The amino acid citrulline normally is not found in the body. It is usually only made when the body converts the amino acid orthithine into arginine. The presence of lingering citrulline in peptides causes the formation of a citrulline antibody that is sent to eliminate it.
When someone is suffering from unusual joint inflammation or arthritis, his or her doctor may order a blood test that looks for citrulline antibodies. The citrulline antibody is often called the rheumatoid factor. This is because citrulline antibodies are present in up to 80 percent of people with rheumatoid arthritis, an autoimmune disease that attacks the joints of the body. The level of citrulline antibodies detected in the body tends to correlate to the severity of the disease.
B lymphocyte cells with Y-shaped antibodies are released into the blood stream or lymph fluids of the body in response to an antigenic stimulus. The antigenic stimulus can be a virus, parasite, bacteria, transplanted organ or other foreign agent. The top arms of the Y-shaped antibody bind to the antigenic stimulus and neutralize it or move it to a white blood cell known as a macrophage to be destroyed. In the case of peptide antibodies, the antibody binds to a specific peptide in a pathogen.
A vaccine for a virus is created by deactivating a pathogen and injecting it into a human body. B lymphocytes detect the deactivated antigens and send out antibodies until they learn which types of antibodies destroy the antigens. In essence, a vaccine protects a person from infection by teaching the antibodies how to detain and destroy a new type of microscopic pathogen.