Skin Immune System

Skin Immune System: Everything You Need To Know


Our immune systems are made up of an expansive network of cells that function throughout the body to protect us from disease and harmful pathogens. Despite the role cells and systems play inside the body, the first line of defense is on the outside. Our skin is one of the most important parts of our immune systems, working to keep out bacteria and keep us healthy before they ever have the chance to make us sick.

Ultimately, the skin is a deeply intricate system that protects us from outside invaders. iwi life is here to help provide some insight into how the skin plays a key role in your immune system — and how you can help it function.

What Is the Skin?

Skin is the largest organ in the body, serving as a protective barrier against germs and the outside elements. Although we may often consider the skin to be everything we can see covering the outside of our body, it is a bit more complex.

The skin is made up of three different layers that each serve their own detailed functions. These are the epidermis, the dermis, and the hypodermis. Your skin is made up of approximately 19 million cellswhile serving as a home for nerve endings, blood vessels, and hair follicles. Altogether, the skin is anything but simple.

What Functions Does the Skin Serve?

Skin Immune System

The skin serves many functions, from regulating your body temperature to protecting your body from bacteria and other germs. Each of the following layers serves its own important functions:


The epidermis is the top layer of skin we can easily see and touch. The epidermis does the following:

  • Protects against outside bacteria, germs, sun, and heat.
  • Constantly creates new skin cells to replenish old skin cells shed daily.
  • Contains important immune cells that fight off potential infection
  • Provides skin color based on the amount of melanin in the body.


Underneath the epidermis, the dermis makes up the middle layer of the skin. The dermis serves even more functions than the layer above it, and it makes up 90% of the skin’s thickness. The following are key functions that the dermis handles:

  • Contains collagen and elastin, which are proteins that help make the skin strong and flexible.
  • Holds the roots of the hair follicles and grows hair.
  • Maintains nerve receptors that support your sense of touch, allowing you to feel temperature and texture, as well as pain.
  • Produces oil through oil glands that reside in the dermis.
  • Houses sweat glands that release sweat through pores in the skin to help regulate body temperature.
  • Transfers nutrients from blood vessels to the dermis to promote healthy skin.


The hypodermis is the fatty bottom layer of skin. The fat in the hypodermis is vital for supporting several of the body’s functions and is responsible for doing the following:

  • Provides a layer of cushion that protects muscles and bones from potential injury in a fall or accident.
  • Serves as a pathway for nerves and blood vessels reaching into the dermis.
  • Regulates body temperature in hot or cold environments.
  • Contains connective tissue that attaches the skin to the muscles and bones.

What Is the Immune System?

The immune system is a comprehensive network of cells, organs, and tissues that defends your body against potential infection by protecting against bacteria, viruses, and other invaders. The immune system is made up of white blood cells, lymph nodes, the spleen, the tonsils, the thymus, bone marrow, the stomach, and the skin. These components work together to prevent pathogens from entering the body and attacking them with immune cells if they do.

How Does the Skin Play a Role in the Immune System?

Skin Immune System

Altogether, the skin is a complicated, necessary organ. The biggest role that the skin plays for the body is acting as a shield against outside threats. However, this shield has a lot more going on underneath the surface, as the ways that the skin keeps out invaders involve some very complex processes.

Both the epidermis and dermis play a role in regulating immune function and preventing outside pathogens from entering the body. Each layer has its own types of cells that fight off potential infection.

Langerhans Cells

Langerhans cells act as some of the first responders to pathogens that reach the body by approaching the skin. The epidermis contains high levels of these cells, which activate in response to potential threats. Langerhans cells are a type of dendritic cell, which are immune cells that alert the immune system of the presence of harmful pathogens.

When a threat is detected, the immune system ignites cells like T cells and B cells which jump into action to stop and fight bacteria or viruses. Langerhans cells play a constant role in the body, consistently monitoring for threats and signaling to the body to produce an immune response if they arrive. 

These cells help prevent infection and play a key role in beginning the overall immune response. Unlike other dendritic cells, Langerhans cells do not move to the lymph nodes, instead signaling to other cells which make the journey.

Immune Cells

Langerhans cells are just part of the expansive range of cells in the skin. Both the dermis and the epidermis support all kinds of immune cells that work to fight off viruses and bacteria. Some of the most important cells that exist in the epidermis are the aforementioned Langerhans cells and T cells, which respond first to potential infection.

Keratinocytes and melanocytes are other, more abundant cells on the outermost portion of the skin. Melanocytes primarily produce melanin that influences skin color, while keratinocytes are crucial for maintaining the skin's strength, protecting against ultraviolet (UV) light from the sun, and catalyzing skin repair. Underneath the epidermis are even more vital immune cells.

The dermis contains a significantly larger number of immune cells, which include the following:

  • Dendritic cells
  • Mast cells
  • Basophils
  • Eosinophils
  • Neutrophils
  • Natural killer (NK) cells
  • Macrophages
  • B cells

Dendritic cells initiate the immune response by sharing information about the invading pathogen, specifically antigens, to other cells in the immune system so they can respond by producing antibodies. Basophils, eosinophils, and neutrophils are all white blood cells called granulocytes that are among the first cells to respond to an infection.

Mast cells are also blood cells, but they remain in tissues in the body rather than spending most of their time in the circulatory system. B cells are white blood cells that are responsible for producing antibodies. Natural killer cells start to kill unrecognizable cells even before the production of antibodies. Once the immune system recognizes a pathogen, macrophages act to destroy the threat. Macrophages surround, or “eat,” foreign cells and pathogens as part of the immune response.

Wound Healing

Wound healing is a crucial function of the skin’s immune system and is a strong example of the skin’s immune response capabilities. Since wounds allow easy entry for bacteria and pathogens, the skin and its cells rush to close and heal the wound as quickly as possible.The wound healing process involves four phases: hemostasis, inflammation, and remodeling. During these phases, the cells in the skin tissue work to close the wound and repair the skin barrier.

Immune cells are involved throughout the entire wound healing process to compensate for the breach in the barrier and quickly respond to threats. Blood clots around the wound to close the opening during the first phase. The second phase involves introducing immune cells to the area to defend against pathogens and prevent infection. These cells all function together to protect the entrance to the skin.

In the third stage, skin cells start to replace the clot along with key members of the skin immune system, like keratinocytes. Lastly, in the remodeling phase, many immune cells begin to exit the wound while macrophages help to remove scar tissue and Langerhans cells begin to take their place in the epidermis.

How Can You Support the Skin’s Immune System?

Skin Immune System

Your skin is a resilient and regenerative organ, able to withstand cuts, burns, and other damage while defending your body’s other organs against external threats. Despite the skin’s resilience, you should still take the proper steps to take care of it and maintain its strength.

Use Sunscreen

Ultraviolet (UV) rays from the sun damage your skin, especially during prolonged exposure. Radiation from the sun can cause keratinocytes to work overtime, alter immune cell response, and even suppress the production of important immune cells, like T cells. As a result, you should protect yourself against the sun to protect your system.

Any time you plan to spend an extended period of time in the sun, you should be sure to apply sunscreen with a sun protection factor (SPF) of at least 30. When spending several hours outside, you should reapply sunscreen every two hours for the most effective support.


Hydration is very important to the health of your skin. Dehydrated skin is not as resilient as moisturized skin, as dry skin is less flexible and can crack and allow pathogens to enter the body. These pathogens can lead to infection, which may show in redness or inflamed areas on the skin. Prevention is the best method for treating dry skin.

Consider applying a lotion after you shower to trap in hydration and rejuvenate your skin, at least daily. It is harder to maintain hydrated skin in dry climates and during the winter, so you should work extra hard to stay moisturized whenever you are up against these conditions and add to your moisturizing routine.

Obtain Crucial Nutrients

To support the skin’s function in the immune system, it is essential to receive a range of nutrients that support the skin barrier and maintin the development of necessary immune cells. Vitamins A, B3, C, and E are all vital for your skin. Vitamins A and C help support collagen production in your skin for strength and flexibility. Vitamin A is found in foods like carrots and squash, while vitamin C is found in green leafy vegetables, peppers, and citrus fruits.

Vitamin B3 is great for supporting hydrated skin, while vitamin E helps maintain hydrated skin and produces antioxidants that support healthy aging. Vitamin B3 is found in many plants and animal-based foods like red meat, poultry, brown rice, and nuts. Vitamin E is found in some plant-based oils, nuts, and seeds.

Other important nutrients for your skin are omega-3 fatty acids, which are polyunsaturated fats that help create the foundations of many cells in our body. These healthy fats can support hydrated skin and healthy skin cells, thus working to maintain a strong skin barrier.

The most popular source of omega-3 fatty acids is fatty fish, like salmon, trout, and tuna, but they can also be found abundantly in algae, the richest plant-based source. Algae may even provide the most efficient source of omega-3s. For example, iwi life’s algae-based Omega-3 supplement, with the addition of polar lipids, allows omega-3s to be absorbed by the body at a rate 1.7x better than omega-3s from other sources.

Support Your Skin’s Function

The skin is a crucial part of your immune system but also has many other vital functions, so you should push to support it at every level. If you have any concerns about the health of your skin, you should talk to your healthcare provider about seeing a dermatologist. At the same time, it always helps to get the vitamins and nutrients you need to help your body maintain strong and healthy skin.

At iwi life, we help you obtain vital nutrients to support the health of your body’s important systems, including your skin, all with the help of our algae-based supplements. Our omega-3 supplement is rich with nutrients that can help support the strength of your skin and promote healthy immune functioning.  


Skin: Layers, Structure and Function | Cleveland Clinic

The Dynamics of the Skin's Immune System | PubMed Central

Organization of the Skin Immune System and Compartmentalized Immune Responses in Infectious Diseases | Clinical Microbiology Reviews

How Langerhans Cells Protect You From Harm | VeryWell Health

Sunlight Effects on Immune System: Is There Something Else in addition to UV-Induced Immunosuppression? | Pub Med Central.

Essential Fatty Acids and Skin Health | Linus Pauling Institute

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