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Skin Immunity And Automatic Repairing Mechanisms

Imagine yourself walking into the doctor’s office to treat an open wound. You walk into the office and the front desk notifies the nurses and doctors you have arrived. You go back to start your vitals and wait to be checked by your doctor. What if I told you this same process happens with your skin when a foreign body comes into contact with an open wound?

This is the process of notifying your immune system that a foreign body has invaded and repair is needed. Deciding how to treat it is one of your skin’s main roles. During this process, there are many different types of cells that are crucial to how well your skin will heal an open wound and dispose of pathogens properly. This entire process is how your skin fights infections, heals traumas and micromanages every cell in your body to keep you healthy and keep you living! This process involves many different cells, multiple types of communications between them, and a lot of simultaneous actions.

2 Type Of Immune Activity

There are two types of immune activity processes in your skin; innate immunity and adaptive immunity. The type of situation we have to deal with will determine which of the immune systems will be notified. Innate immunity is your body’s way of understanding a new situation and coming up with a plan to attack and heal. Adaptive immunity is used to fight and heal occurrences that we have previously experienced. Your body is constantly taking notes of your daily experiences to make your immune system stronger, and in turn, a lot smarter.

Healing wounds and disposing of pathogenic material allows your body to study the events and produce a game plan to treat it in the future. This is similar to the medical chart your doctor keeps in their files of your medical history to determine if there is anything in your past that is worth relating back to. These two systems correlate with each other constantly, ensuring they remain synergized. Once a microbe enters your skin through the wound, specific cells are notified to start an attack on the pathogens. These cells are present in healing any damage done to the epidermis and dermis tissue.

The Immune System’s Call To Action

The first to start this process is your langerhans cells, which survey your epidermis and dermis tissues constantly. These cells send messages to your immune system that there is something foreign to the body. Think of these cells as the front desk receptionist; keeping everything organized and keeping the system up to date of new patients. Just like checking into your doctor’s office, your langerhans cells check every single organism into the system to keep track of who is allowed in and who should be removed.

These cells have multiple roles, such as telling your immune system when it needs to repair physical trauma, when a foreign body has made its way into your skin, or if your body is experiencing a new pathogen. Your langerhans cells send messages via antigens to your T lymphocytes (T-Cells), through your lymph vessels into your lymph nodes; that your immune system needs to address. This process is the first step of your immune system’s call to action.

Function of T-Cells

Your T-cells will then begin to transcribe the message sent from the langerhans cells to decide how to treat the situation. The antigen that your langerhans cells have sent, is similar to a sticky-note. It is attached to the microorganism that will tell your T-Cells that they need to figure out a solution to the problem. T-cells are white blood cells that are part of your immune system that help fight infections as well as release chemicals to stimulate skin repairing cells.

There are two types of T-Cells in your body that are both active in immune system stimulation. Natural killer T-cells, also known as cytotoxic T cells (or NK cells), physically fight an infection. Helper T-cells coordinate the attack on foreign invaders and secrete cytokines to further stimulate white blood cell production. Think of them as the different medical professionals in your doctors office, ensuring that you receive the correct treatment.

T-cells have a specific antigen that they can treat, which forces them to be very critical when fighting a foreign body. When killing a pathogen, your helper T-cells express stimulation of cytokines to alert all immune system cells that it’s time to fight! Your cytotoxic T-cells physically fight and kill the foreign invader.

B-Cells

Fighting with your T-cells is the B lymphocyte (B-cell), also located in your lymph vessels and lymph nodes. In response to the helper T-cell chemical command, B-cells will form plasma cells to duplicate into antibodies and mimic the antigen it is trying to fight. This allows the antibodies to trap the invader and grant cytotoxic T-cells the opportunity to kill. After the invader has been defeated, B-cells are responsible for the clean up of the left over cellular material that has been abandoned. The B-cells will then gather up all cellular material to allow protein eating Macrophages to literally eat away the mess, allowing the tissue repairing process to begin.

Wound Repair Begins

After removing harmful foreign bodies, the wound-repair system starts. This process is demonstrated by the physical inflammation of the wound, increasing platelet formation to create blood clots to prevent blood loss and the surrounding  affected area. This mechanism allows your epidermis and dermis tissues to create a temporary block for your open blood vessels to stop further exposure to the outside world. Once the blood clots have completed formation, it will result in what we know as a “scab”.  Your helper T-Cells stimulate repairing cells such as epidermal  growth factors, fibroblasts, and keratinocytes to involve themselves in creating new tissue.

Fibroblast cells and epidermal growth factors help reform the extracellular matrix, which encourages new tissue to grow. Macrophages will then allow specific cells such as myofibroblasts to fill in missing muscle tissue. By contracting, these myofibroblasts will encourage new tissue to form the closure of the wounded site. As time continues these macrophages will die and create new cells to continue to repair the area until it is complete. Formation of new skin cells such as keratinocytes, which are a main protein in skin and hair, will also encourage new skin cell growth in the epidermal layers. Keratinocytes will remove unhealthy cells of the scar tissue and replace them with newer cells, to create a healthy functioning barrier once again. 

Your skin is a very complex organ, which means it has millions of different cells to orchestrate a simple task, even as little as healing a small cut. Always ensure that you are protecting your skin and giving it proper nutrition to encourage these processes to move more swiftly and possibly, even more effectively!

Source Material

Dr. Biology. (2011, February 16). B-cells. ASU – Ask A Biologist. Retrieved April 1, 2021 from https://askabiologist.asu.edu/b-cell

Dr. Biology. (2011, February 16). T-cells. ASU – Ask A Biologist. Retrieved April 1, 2021 from https://askabiologist.asu.edu/t-cell

Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. Chapter 8, T Cell-Mediated Immunity. Available from: https://www.ncbi.nlm.nih.gov/books/NBK10762/

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