Antibody - Any of a large variety of proteins normally present in the body or produced in response to an antigen which it neutralizes, thus producing an immune response
Antigen - Any substance (as a toxin or enzyme) that stimulates an immune response in the body (especially the production of antibodies)
(Definitions taken from WordWeb)
Antibodies respond to antigens, latching onto them, destroying them, and in turn the body excretes them both as waste, removing them from the body.
Antibodies that are formed in people that were infected by an illness, but recovered, are taken and through a process in a laboratory are made into vaccines, providing the same immunity to the illness that the original host had. One popular vaccine that everyone knows about is the "flu-shot".
Light Chains are part of the protein sequence that make up these antibodies that the human body relies on to stave off infections. When the proteins are overproduced, the immune system is compromised, because the antibodies can no longer function properly.
What results is what is called "Light Chain Deposition Disease" or LCDD.
LCDD is characterized by deposition of monoclonal, amorphous light chains. Sites of light-chain deposition include the kidney, liver, heart, small intestine, spleen, skin, nervous system, and bone marrow. (1)
The sites that are affected by LCDD can cease to function properly, and can slowly cease to function altogether.
