What are B-Cells in Your Immune System?

How B-Lymphocytes Work in Your Immune System

B-cells. Science Picture Co Collection Mix: Subjects/Getty Images

Definition of B-Cells

B-cell is another name for B-lymphocytes, a type of white blood cell that has a large role in protecting your body from infection by producing antibodies. Without B-cells and antibodies, your body could not fight off bacteria and viruses very effectively and you would not have long-lasting immunity after recovering from an infection or having an immunization.

B-cells, like other white blood cells, are created in the bone marrow from stem cells.

After maturation, B-cells are present in your blood and in your lymph nodes.

Thre are two main types of lymphocytes, T-cells, and B-cells. When you have a CBC blood test done, the number and percentage of lymphocytes are reported, but there is no differentiation as to which are T-cells and which are B-cells.

What Do B-Cells Do in a Healthy Body?

The main job of B-cells is to fight infection by producing antibodies. B-cells get activated when an infection occurs and they produce molecules called antibodies that attach to the surface of the infectious agent. These antibodies either kill the infection-causing organism or make it prone to attack by other white blood cells. They play a major role in the immune system, which guards the body against infection.

How Do B-Cells Give Us Immunity?

A young B-cell, called a naive B-cell, circulates in the bloodstream, usually ending up in the spleen or lymph nodes.

It gets activated by an antigen, which can be any substance the body thinks is foreign, such as a piece of a virus. T-cells are often involved in this process. The B-cell begins to make antibodies to that substance and it transforms into a plasma B-cell.

Each plasma B-cell makes antibodies to only one antigen, they are very specific.

Luckily, there are millions of them in our body so we can fight many different types of infection. Throughout the life of a B-cell, it makes these antibodies. They settle down mostly in the spleen and lymph nodes to pump out antibodies.

Some of the activated B-cells become memory B-cells, which have very long lives in the bone marrow, lymph nodes and spleen. They remember the antigen they are specific for and are ready to respond quickly if they see it again. These are the cells that give us long-lasting immunity to different invaders.

When you get immunized, the vaccine contains antigens that stimulate the B-cells to produce antibodies that will then attack the virus or bacteria you are being immunized against. This mimics what is happening in your body when you are infected with that germ but without the risks of the disease caused by the germ. Because B-cells have long memories, they can produce antibodies against those germs for months and years, giving you a period of immunity.

Disorders of B-Lymphocytes

Sometimes B-cells produce antibodies to elements of our own cells, autoantibodies, and this can result in autoimmune diseases such as rheumatoid arthritis, lupus, multiple sclerosis and type 1 diabetes.

These are cases of our immune system attacking our healthy tissues to produce a disease.

B-cells may be malignantly transformed in chronic lymphocytic leukemia, acute lymphoblastic leukemia, and lymphoma.


B Cells and Antibodies, Molecular Biology of the Cell. 4th edition.Copyright 2002, Bruce Alberts,, et. al.

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