B-Cell

What are B cells?

B cells are a type of lymphocyte that are responsible for the humoral immunity component of the adaptive immune system. These white blood cells produce antibodies, which play a key part in immunity. Each B cell contains a single round nucleus.

Lymphocytes account for about 25% of white blood cells, and B cells represent approximately 10% of total lymphocytes.

Where do B cells originate? Where do B cells mature?

B cells both originate from and mature in the bone marrow, which is the soft fatty tissue inside bones.

What is the major function of B cells?

B cells produce antibodies, or Y-shaped chromosomes that are created by the immune system to stop foreign substances from harming the body. B cells have B cell receptors (BCRs) on their surface, which they use to bind to a specific protein.

Once the B cells bind to this protein, called an antigen, they release antibodies that stick to the antigen and prevent it from harming the body. Then, the B cells secrete cytokines to attract other immune cells. They also present the antigens to T cells, which they recognize using their T cell receptors (TCRs). The T cells destroy the antigens.

How are B cells activated?

When infectious agents, such as bacteria, enter the body, pieces of their machinery can be visible on the surface of their cells. These pieces are called antigens, and B cells activate when they encounter and recognize antigens.

B cells have B cell receptors (BCRs) on their surface, and these BCRs bind to specific antigens. Once the cell binds to the antigens, activation begins.

How do B cells recognize antigens?

B cells recognize infectious agents by the shape of the antigens on their surfaces. The cells descended from a single B cell produce the same antibodies and remember the invader and antigens that led to their formation. This memory means that B cells produce the antibodies that counteracted the original antigen, protecting the immune system from a second attack.

What is B cell isolation?

B cell isolation is the separation of B cells from other cell populations. B cells are identified by their surface markers, CD19 and CD20.

Activated B cells become plasma cells and produce large amounts of antibodies. These activated B cells can be identified using the CD138 marker.

The same isolation methods used for T cell isolation can be used for B cell isolation.

What are the methods of B cell isolation?

There are a few different approaches to B cell isolation.

One method is selection. Positive selection is when B cells are targeted by the removal mechanism and retained for downstream analysis. On the other hand, negative selection is when other cell types are removed to leave the B cells untouched.

B cell depletion is another approach, where a single cell type—in this case, B cells—is removed from a biological sample.

What is the difference between B cells and T cells?

There are two types of lymphocytes: B cells and T cells. They are both critical parts of the immune response and are interconnected, because T cells are required to activate B cells.

While both B cells and T cells are involved in triggering the immune response, the main difference between the two is that T cells can only recognize viral antigens on the outside of infected cells and B cells can only identify the surface antigens of the infectious agents themselves.

What diseases affect B cells?

An unusually high B cell count can indicate several issues in the human body:

  • Multiple myeloma
  • DiGeorge syndrome
  • Chronic lymphocytic leukemia
  • Blood cancer

A low B cell count could be a sign of acute lymphoblastic leukemia or a disease that weakens the immune system, such as HIV. Additionally, lymphocytopenia (also known as lymphopenia) can be caused by a low lymphocyte count.

Is it possible to isolate DNA from B cells?

Yes. DNA is encased in the nucleus of cells, and B cells have nuclei.