How are antibodies produced in response to an infection?

Antibodies are produced by B lymphocytes in response to an infection, as part of the immune system's defence mechanism.

When a pathogen, such as a virus or bacteria, enters the body, it triggers an immune response. The pathogen contains specific proteins called antigens on its surface. These antigens are recognised as foreign by the immune system, which triggers the production of antibodies.

The production of antibodies is carried out by a type of white blood cell called a B lymphocyte. Each B lymphocyte is programmed to make one specific antibody. When a B lymphocyte encounters its matching antigen, it is stimulated to divide and produce many identical cells, known as a clone. These cloned cells then produce large amounts of the specific antibody that can recognise and bind to the antigen.

The antibodies produced are specific to the antigen of the pathogen that caused the infection. They work by binding to the antigens on the surface of the pathogen, which marks it for destruction by other immune cells. This process is known as opsonisation. Some of the antibodies can also neutralise the pathogen directly, by blocking the parts of the pathogen that cause damage.

In addition to producing antibodies, some of the B lymphocytes become memory cells. These cells remain in the body long after the infection has been cleared, and are able to respond quickly if the same pathogen infects the body again. They do this by rapidly producing large amounts of the specific antibody. This is the basis of immunity to future infections by the same pathogen.

The production of antibodies is a complex process that involves many different cells and molecules of the immune system. It is a key part of the body's defence against infection, and is the basis for the effectiveness of vaccines, which stimulate the production of antibodies to specific pathogens.