B cells mature into plasma cells to make antibodies. Antibodies
are blood proteins also known as immunoglobulins. Antibodies attach
themselves to invading pathogens and make them easier for other
cells and complement to kill. Each antibody has a unique shape that
gives it the ability to stick to a certain pathogen. There are five
main types of antibodies:
IgM antibodies are the first to respond to an invading pathogen.
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 after IgM antibodies.
These antibodies are found in large quantities in plasma and work
in the blood and tissues of the body. They bind with destructive
pathogens so that the immune cells (for example macrophage) have
an easier time ingesting them. IgG antibodies can pass from a
mother to her unborn baby through the placenta.
IgA is produced along the surface linings of the lungs and
intestines and is predominant in body fluids such as tears, saliva,
and mucus. This antibody represents the first line of defence
against infection in the respiratory tract and intestines. IgA
also passes from mothers to newborns through breast milk.
IgE is normally present in trace amounts and is important in
allergic reactions.
IgD may be present on the surface of B cells.
Antibodies make pathogens easier to kill by alerting the immune
system that the germs need to be destroyed.
