B Ready

What am I looking at?

This is a colored scanning electron microscopy image of a human B lymphocyte – a type of white blood cell that develops from stem cells in the bone marrow.

Click on the right arrow to see another image of a B cell.

Biology in the background

The human immune system is divided into two parts – the innate immune system and the adaptive immune system. The innate system is the first line of defense against disease and is composed of tissues and cells that directly block or destroy pathogens upon contact. The adaptive system is more complex and provides a lasting defense against specific pathogens. B cells, like the one seen here, are an important part of the adaptive immune system.

B cells recognize pathogens in the body and instead of destroying those pathogens themselves, they create antibodies, called antigens, that bind to specific targets on the surface of the pathogen. These antibodies act as a marker for other cells in the immune system to target the pathogen and either destroy it or prevent it from entering the cells they are aiming for. In addition, B cells have a “memory.” Once your adaptive immune system has encountered a specific pathogen and produced antibodies against it, the B cells can produce antibodies for that pathogen much more quickly and in greater numbers if they encounter it again. This process often heads off an infection before it can take hold.

This is the principle behind many vaccines. Vaccines introduce part of a pathogen, either mRNA coding for an antigen or a whole but inactive pathogen, into the body. This is recognized by the body’s B cells, which create antibodies and memory B cells. Then if the actual pathogen ever enters the body, the B cells are ready to produce adequate antibodies to prevent a severe infection.

In humans, B cells can reach about 10 micrometers across, or roughly 7.5 times smaller than the width of a human hair.

Technique

This image was created using electron microscopy.