Antibodies

Antibodies (also known as immunoglobulins) are Y shaped molecules that attach to antigens. In doing so, they may deactivate the harmful molecule, bind with complement to destroy it, or usually just mark the cell, attracting other immune cells to deal with it.

Plasma cells

Antibodies are produced by plasma cells, which are formed from B lymphocytes.

Types

There are 5 main types of immunoglobulin:

Most important

These are the most important, and are remembered with the phrase "My Gosh". The M protein comes first, and then the G protein kicks off second.

• IgM - found on surface of B cells, and tends to do IgG's job in primary response, until enough IgG has built up in the area. Is the largest antibody, with a pentameric shape. Has a J chain. CD40 ligand deficiency results from lack of these.
• IgG - Provides the majority of antibody immunity, in 4 forms. Forms the secondary response. lack of this causes hypogammaglobulinaemia in infants.

Less important

• IgA - found in mucus, eg. gut or respiratory tract, and prevents pathogens taking over mucosal areas. Found in external secretions. Has a J chain.
• IgD - nearly always a protein on B lymphocytes rather than on its own.
• IgE - designed to deal with parasites, but also involved in allergy.