WHITE BLOOD CELLS THAT HAVE AN AMAZING MEMORY
WHAT ARE B-CELLS?
A B-cell is a type of lymphocyte (white blood cell) that produces antibodies. An antibody is a protein found in the blood that fights the effects of an antigen. An antigen is just about any foreign substance that stimulates a response from your immune system. It may be a product or a part of a virus, fungi, bacteria, parasite, or harmful chemical. Generally speaking, when antigens gain access to your body, antibodies are produced to fight them. B-cells are an essential part of adaptive immunity, a subsystem of your immune system that develops over a lifetime. At the core of this subsystem are T-cells and B-cells. If you want to know more about T-cells, click here. We’ll give our attention to B-cells in this article.
Antibodies produced by B-cells or B lymphocytes eliminate antigens or the harmful microorganism connected with a certain antigen. They also have an amazing memory in that they remember and recognise specific antigens so the immune system can immediately launch a successful immune response if the harmful microorganism gains access to the body again in subsequent infections.
WHERE ARE B-CELLS PRODUCED AND LOCATED?
Before you are born, B-cells are produced and stored in your liver. After birth, your B-cells develop from stem cells found in the bone marrow. Bone marrow is the spongy tissue found inside your bones. The process in which stem cells develop into B-cells is called haematopoiesis. When the B-cells are fully developed, they travel to various parts of the lymphatic system, like the lymph nodes and spleen.
Some B-cells also travel to parts of your body that have mucosal linings. These parts include the nasal passages, bronchial airways, and colon. They migrate there to provide defence because these areas are easily triggered and attacked by antigens or harmful microorganisms.
WHAT ARE THE DIFFERENT KINDS OF B-CELLS?
Fully developed B-cells have two predominant kinds: memory cells and plasma cells. Both kinds are involved in protecting you against harmful microorganisms.
- Memory cells are B-cells that have the ability to remember the identity of certain antigens. These cells are vital when the body encounters the same antigen in the future, resulting in the immune system's ability to assemble and provide a defence quickly. They’re better termed as future defenders. The majority of vaccines are effective because they expose the immune system to antigens that memory cells remember. If an antigen or harmful microorganism gains access to the body, the body recalls the antigen and immediately prepares an attack against it.
- Plasma cells are B-cells that produce and release antibodies when antigens enter the body. They’re appropriately regarded as antibody factories. A single plasma cell is estimated to release hundreds to thousands of antibodies per second. Plasma cells are also called effector cells, effector B-cells or plasmacytes.
HOW DO B-CELLS DIFFER FROM T-CELLS?
Both B-cells and T-cells belong to a group of white blood cells that fight harmful microorganisms and some diseases. What sets them apart from each other are their respective roles in the adaptive immune response. B-cells produce and release antibodies when antigens are present in your body. The antibodies actually exert the action (eliminating the antigen) of B-cells and not the B-cells themselves directly. On the other hand, T-cells (cytotoxic or killer T-cells) directly attack the harmful microorganisms and the cells they have infected. Other types of T-cells help modulate the immune response.
HOW DO B-CELLS RESPOND TO AN ANTIGEN?
B-cell response to the presence of an antigen is best described together in part with the T-cell response. Below is a summary of an immune response that includes B-cells:
- A harmful microorganism with its antigen enters the body. Let’s say, for example, you’re starting to have a cold. The usual microorganism responsible for the common cold is a virus called the rhinovirus. On the surface of a rhinovirus is its antigen, made up of proteins. A special type of cell called an antigen-presenting cell (or APC for short) attaches itself to the antigen of a rhinovirus and breaks it down into smaller parts.
- The APC presents and binds these antigen parts to a large protein called the MHC-II or major histocompatibility-II complex.
- The MHC-II binds to helper T-cells. This binding activates T-cells (helper T-cells) that stimulate B-cells to participate in the immune response.
- The stimulated B-cells then make numerous copies or clones of themselves. Some of the clones become memory cells, and some become plasma cells.
- The plasma cells produce millions of tailor-made antibodies to eliminate the rhinovirus with its antigen. Memory cells remember the identity of that specific rhinovirus with its antigen for future reference. If the same antigen enters the body, these memory cells jump into action, skipping the antigen presentation. To put things into perspective, up to 170 distinct types of rhinoviruses are circulating worldwide. Each of these types has its unique antigen. Suppose you encounter the same antigen as before. In that case, your memory cells may protect your body from a longer duration of infection, or you may experience a decrease in the severity of your symptoms, or both. Sometimes, you may not experience symptoms because you have sufficient antibodies to protect your body.
- The antibodies attach themselves to the antigen of the rhinovirus and inhibit it from doing additional damage to the body.
Note: The process given above is an oversimplification of how B-cells participate in the immune response. In reality, there are much more complex processes that come into play. In addition, several factors also affect how B-cells act during the immune response.
Whenever you’re sick or have an infection, your white blood cells, including your B-cells and T-cells, increase in numbers to help fight the infection or disease. B-cells, in particular, indirectly fight the infection by producing antibodies. B-cells also protect from future infections. If you want to take good care of your B-cells, focus your efforts on keeping your immune system healthy as a whole. Click here for our recommendations on how to do that.
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