What Are Antibodies? Types and Functions

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Ever thought of what your body uses in identifying disease pathogens and destroying them? It’s nothing else but antibodies.

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Everyone knows that their bodies fight off diseases but not everyone knows how the body does it. If you are wondering how your immune protects your body, then read this post to the end to find out how.

Table of Contents

What Are Antibodies?

Antibodies are blood proteins produced in response to specific antigens. Your body uses antibodies to fight off antigen and invaders.

Antibodies work by combining with foreign invaders and disease pathogens like viruses, bacteria, and fungi chemically. They also combine with foreign substances in the blood.

They bind like lock and key to the foreign invaders. Antibodies serve as the search battalion of the immune system search and destroy team.

Antibodies are also called immunoglobulins and they travel through the bloodstream. They are also found in bodily fluids. Your immune system makes use of these to identify and fight off threats to your body.

Their main job is to find an enemy and mark it for destruction.

What Are Antigens?

Antigens are foreign intruders, microbes, or any substance your body recognizes as foreign. Once your immune system locates them, it creates an immune response.

Examples of antigens are incompatible blood cell types, pollen, viruses, bacteria, etc.

How Do Antibodies Work?

Antibodies first and foremost recognize antigens by identifying antigenic determinants. These are specific areas on the surface of antigens.

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Once your antibodies recognize these antigenic determinants, it will bind to the determinants and tag it as an intruder. It will label it for destruction so that your other immune cells can see it and destroy it.

Each antibody can only attack for one antigen because it is fitted with special receptors that can bind only to that antigen. For example, the antibody your body makes to destroy the chickenpox virus and only attack a chicken pox virus and no other microbe.

How Are Antibodies Produced?

The B Cells (B lymphocytes, a special kind of white blood cells produced in the stem cells of the bone marrow) produce antibodies.

The presence of a particular antigen activates B cells and they develop into plasma cells.

These plasma cells create antigens specific to certain antigens. They produce the antibodies critical to the part of the immune system called the humoral immune system.

This part of the immune system depends on the circulation of antibodies in body fluids to function. It needs antibodies in blood serums to identify these invaders and fight them off.

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When a new antigen enters the body and your body is not familiar with it or has never encountered it before, it takes a while before your body acts.

Your body can take up to 2 weeks for the plasma cells to produce enough antibodies for this new antigen in order to counteract it.

Once your body has the infection under control, it reduces the production of the antibodies and a little sample of the antibody remains in your bloodstream and continues circulating.

If this particular antigen should attack again, your antibody response will be faster, quicker, and more forceful.

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How Do Antibodies Work?

Your immune system is triggered when an antigen enters your body. Chemical signals are sent and the different parts of your immune system are alerted and called for action.

Then the first thing that happens is that the B cells meet the invaders and create antibodies to match the antigens. After creating the antibodies, they stick to the invader and make it for attack.

The T cells (thymus cells) are the next to act. They attack the antigen which the B cells have marked.

After the antigen has been destroyed, the phagocytes, the cleanup crew comes along. These large cells consume the dead invaders and eat the leftovers of the infection.

Isn’t the human body amazing? Little wonder that Holy Book says we are fearfully and wonderfully made.

How Do Antibodies Look?

An antibody or immunoglobulin is a Y-shaped molecule with 2 short polypeptide chains called the light chains. It also has 2 longer polypeptide chains Heavy chains.

The 2 light chains are identical to each other and the 2 heavy chains are also identical to each other. At the ends of both the light and heavy chains (in the areas that form the arms of the Y-shaped structures) are found the regions known as the antigen-binding sites.

This antigen-binding site is the area of the antibody that recognizes specific antigenic determinants and bind to the antigens. Different antibodies recognize different antigens, hence, each antigen-binding site is different for different antibodies.

This area of the antigens that are different is known as the variable region. While the stems of the Y-shaped molecule formed by the longer region of the heavy chain is called the constant region.

5 Types of Antibodies

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There are 5 main types of antibodies and each have a unique role they play in your immune response. They have different structures of heavy chains in their molecules.

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1. Immunoglobulin G (IgG)

These are the most plentiful antibodies in circulation. They have the ability to cross the blood vessels and even the placenta to provide protection to a growing fetus.

It works by tagging a pathogen so that other immune cells or proteins can recognize it and attack it or it triggers your body to release toxins to directly destroy the pathogen/microbe.

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IgG is implicated in autoimmune diseases as it triggers an undesirable immune response and cause the immune system to attack its own cells, tissues, or organs.

The heavy chain type in this antibody is a gamma chain. This type accounts for 75% of all antibodies in your body.

2. Immunoglobulin M (IgM)

These are the most massive antibodies and one of the first recruited by the immune system in fighting infections.

They contain 5 Y-shaped sections. Each section has 2 light chains and 2 heavy chains. Each Y-shaped section is also attached to a J chain, a joining unit.

IgM antibodies play a very important role in immune response. They are the initial respondents to new antigens in the body. Their population explodes when your body is confronted with an infectious organism.

Invaders are destroyed as IgA takes over. This antibody is produced by B cells and it works by binding to a pathogen and spurring other antibodies and immune cells to attack the pathogen.

A subclass of IgM B cells called the “memory B cells” remembers every pathogen your body has destroyed. If you are to get exposed to the same pathogen again, these memory B cells will remember and help your body attack more quickly and fiercer.

The type of heavy chain in this antibody is a mu chain.

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3. Immunoglobulin A (IgA)

This type of antibody is found mainly in body fluids like mucus, saliva, tears, breast milk, and sweat. It is also found in mucosal tissues like the intestines, vagina, and mouth.

The main function of this antibody is to prevent antigens from infecting your cells and entering your circulatory system. It is produced by the B cells and secreted from a thin layer within the mucosal tissues.

This thin layer is called the lamina propria. IgA makes up 15% of all antibodies found in the human body and it is one of the first lines of defense against infection.

It works by binding to pathogens and tags them for destruction. It prevents them from sticking to the epithelium which lines your body tissues.

IgA has been implicated with hypersensitive reactions in people with autoimmune disorders like Celiac disease. The type of heavy chain in this molecule is an alpha chain.

4. Immunoglobulin D (IgD)

The role of this antibody is not yet known but it is highly important in the early stages of immune responses.

It is located on the surface membrane of B cells that are matured to instigate immune response when needed. It does not circulate like other antibodies. The heavy chain in this antibody is the delta chain.

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IgD is a signaling antibody and incites the release of IgM and other front-line antibodies to fight off diseases and infections. it accounts for 0.25% of all antibodies in humans.

This is the least understood antibody but we know it plays an important role in kick-starting immune response. Very little is known about its role and how it works in other parts of the immune system.

5. Immunoglobulin E (IgE)

This antibody is present mostly in mucus and saliva. It is involved in allergic responses to antigens in the mucosal membranes, skin, and lungs. The heavy chain in this antibody is an epsilon chain.

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IgE is produced by B cells secreted by the lymph nodes or other lymphoid tissues near the area of the allergen. This antibody works by binding to an allergen.

When it does this, it triggers a cascade of events. Some subclass of the white blood cells like the basophils and mast cells are released to break open and release histamine into the bloodstream.

Histamine is responsible for the allergy symptoms. IgE protects your body from parasitic infections and even parasitic worms like helminths (tapeworms).

There are a few subclasses of immunoglobulins in humans. The differences in these subclasses are based on small differences in the heavy chain units of antibodies in the same class.

The light chains found in antibodies are in 2 forms, the kappa and the lambda chains.

What Is Active And Passive Immunity?

Your body develops immunity when it is resistant to a specific disease and there are 2 ways your body develops immunity: active immunity and passive immunity.

Active immunity is gotten from your own immune system and it has a long lasting effect. Sometimes, it lasts for one’s entire life. Active immunity has more advantages than passive immunity.

There are two ways of getting active immunity. The first is natural immunity in which a person who survives a disease or an infection develops antibodies to that disease.

In this case, your body produces antibodies through when you get exposed to the disease.

The second way to get active immunity is when you receive a vaccine of a killed or weakened of the disease. This is known is known as vaccine-induced immunity.

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Passive immunity is gotten by receiving antibodies to a disease.

A lot of people need to know how their bodies and immune systems works, it will help people appreciate their bodies and support them with right diet and healthy lifestyles.

We hope this post answers all the questions you have about antibodies and your immune system.

Sources;

  1. Antibodies Britannica,
  2. Types of antibodies Frontiers, Nature, SD, MDPI, Frontiers, SD, SD, SD, NCBI, SD,
  3. Functions of antibodies JACI, NCBI, NCBI, NCBI,
Antibodies
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Faith Ebiojo David
I am a Biochemist and Naturopath, I love writing and educating people on health and wellness matters.
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