When B cells encounter disease-causing substances, they respond by maturing into plasma cells which produce antibodies. Antibodies are highly specialized proteins in the blood also known as immunoglobulins. Antibodies attach themselves
to foreign invaders and mark them for destruction.
There are five main types of antibodies:
- IgM antibodies are the first to respond. They offer important protection during the early days of infection. These antibodies tend to stay in the bloodstream where they aid in killing bacteria.
- IgG antibodies are the next to respond. These antibodies are formed in large quantities and work in the blood and tissues of the body. They bind to pathogens so that the immune cells have an easier time destroying them. IgG
antibodies can pass from a mother to her unborn baby through the placenta.
- IgA antibodies are secreted in body fluids such as tears, saliva, and mucus. They protect against infection in the respiratory tract and intestines. These antibodies can pass from mothers to newborns through breast milk.
- IgE antibodies are normally present in trace amounts and are important in allergic reactions.
- IgD antibodies may be present on the surface of B cells but their function is not fully understood at this time.
Antibodies make pathogens easier to kill by alerting the immune system that the germs need to be destroyed.