Understanding Your Body’s Defenders: A Simple Guide to Antibodies

*Disclaimer: This is a very simplified version of antibodies. Some topics in this article are more complex and require a deeper understanding of molecular processes. This is post is designed to enhance your critical thinking and provide the basics. Not just the cherry picked information provided by the media.

Once COVID-19 vaccines started rolling out, several complex topics garnered media attention. These included antibodies, natural vs artificial immunity, and immunity duration became a huge conversation. The immune system is an incredible creation and more complex than most people give it credit for. I still remember being so blown away at everything I learned in my first Immunology class as an undergrad. My hope is this post will provide you with a better understanding of your body’s defenses.

I decided Antibodies and immunity was the best place to start for the In Layman’s Terms section of this blog, because they are such a popular topic lately. We will cover antibody “anatomy”, the 5 types, and how they are triggered to respond. Further details on immunity specifically will be covered in a separate post.

Helpful Vocabulary:

  • Antibody: any of numerous Y-shaped protein molecules produced by B cells as a primary immune defense, each molecule and its clones having a unique binding site that can combine with the complementary site of a foreign antigen, as on a virus or bacterium, thereby disabling the antigen and signaling other immune defenses
  • B-cells: white blood cells that produce antibodies.
  • T-cells: any of several closely related lymphocytes, developed in the thymus, that circulate in the blood and lymph and orchestrate the immune system’s response to infected or malignant cells, either by lymphokine secretions or by direct contact.
  • Immunoglobulin: another name for antibodies, abbreviation Ig. Refers to the 5 types of antibodies: IgA, IgD, IgE, IgG, IgM.
  • Antigen: any substance, such as a protein, carbohydrate, virus, bacterium, that, on entering the body, can stimulate an immune response.
  • Binding site: a specific location on a molecule (such as an antibody) that attaches to another molecule (such as an antigen).
  • Variable region: portion of the antibody that is unique in each antibody type, that binds with a specific antigen.
  • Mast Cells: a large granular cell, common in connective tissue, that produces heparin, histamine, and serotonin.

Antibody Anatomy

Figure 1. Labeled diagram of an antibody. Light blue and light orange regions indicate the variable region.

The above image shows a labeled, basic diagram of an antibody. The antigen binding sites are where it attaches to an antigen (the invader). Notably, these sites are also the variable region (denoted by the lighter colors). This is what allows antibodies to be specific. All cells have receptors on their surface, but for an antibody to attack it, it must be specifically built for that receptor. When you get sick, your body sends the alarm for an intruder. If it’s a pathogen (antigen) encountered before, such as the flu, your immune system begins pumping out antibodies with binding sites specifically for the flu. In short, antibodies for strep throat are not effective against the flu and vice versa.

Different Antibody Types:

As mentioned previously, there are 5 different antibody variations in humans. Below is a table to provide the basics of each type.

AntibodyLocationFunction
IgASaliva, tears, mucus, breast milk and intestinal fluid.Protects against ingested and inhaled pathogens.
IgDFound on the surface of your B cells.Unclear, experts think that IgD supports B cell maturation and activation
IgEMainly in your skin, lungs and mucus membranesResponsible for allergic reactions, cause release of histamine by mast cells
IgGMainly in blood and tissue fluidsMost common antibody, making up approximately 70% to 75% of all immunoglobulins in your body. Helps protect your body from viral and bacterial infections.
IgMBlood and lymph systemFirst line of defense against infection, also aid in immune regulation
Table outlining each type of antibody and their function.

In addition to the antibodies, your body also utilizes B-lymphocytes (B-cells) and T-lymphocytes (T-cells) to manage an immune response. Typically, the B-cells will trigger production of the antibodies needed to attack a pathogen. T-cells are responsible for destroying your cells already infected by the pathogen. This can also apply to cancerous cells.

Triggering an Immune Response

When your body is invaded by a virus, bacteria, or other toxin it sets off an alarm based off the antigen on the surface of the invader. Essentially, your body is very sensitive to anything that has a “non-human” antigen on the surface. Of course, there are pathogens that can run around incognito but that will be a topic for another post. To keep it simple for this introduction, just think of the pathogens as a stranger breaking into your house. You would immediately call 911 for reinforcement and perhaps also reach for a self defense weapon. When the pathogen enters your body, your immune system begins pumping out antibodies specifically for that invader. If it is something you have been infected with before, your immune response will be much faster than if encountering a novel invader. Development of an immune response will be covered in the next installment of this series and will be linked here when available.

Resources:


Comments

Leave a Reply

Your email address will not be published. Required fields are marked *

Verified by MonsterInsights