The immune system is the body’s defence mechanism – the army with which the body protects itself against disease-causing organisms such as viruses, bacteria or fungi, which are known as pathogens. The troops that make up this army are various types of white blood cells, which are produced in the bone marrow.
When working well, the immune system is constantly vigilant in order to protect us from infection, infestation and general invasion by bugs of all descriptions.
An invading pathogen has many obstacles to surmount in order to infect the body. Firstly, the pathogen must penetrate the external barrier of the skin, or survive the stomach acid if entering via the digestive tract. The nasal passages might seem a good potential entry route, but they secrete mucus that traps and then flushes away pathogenic matter. Saliva and tears both contain antibacterial enzymes, to neutralise pathogens that attempt to enter via the mouth or eyes.
Pathogens that make it past the salivary enzymes and stomach acid still have to contend with gastrointestinal mucus, which can trap and expel them. Additionally, the gut contains more than 70% of the body’s supply of immune cells, which seek out and destroy pathogens that have made it past the mouth and stomach. Any pathogenic matter that gets into the bloodstream from the digestive tract will have to travel through the liver, where more immune cells are on hand to deal with them.
If a pathogen gets past all these defences and manages to infect tissue cells, an immune response is triggered.
- The damaged cells call for help (by releasing chemicals such as TNF-α, that attract immune cells).
- Immune cells come along and identify the pathogen as bad/ unfriendly to the body and call up more troops that attack and hopefully kill the pathogen. Symptoms of this attack are a raised temperature, feeling tired and a little achy, slightly swollen lymph glands, and possibly a runny nose.
- The immune system can also make an antibody for that pathogen. An antibody is a bit like a customised pair of handcuffs, which attach to the baddie and make it easier for the alerted troops to spot and kill it. The antibody remains in the system, ready to use if that particular bug turns up again.
The immune system has two main ways of responding to an invader.
- Non-specific response – This is when T cells identify an invader and initiate an immune response that results in the pathogen being destroyed “on the spot”. This is random and the T cells have to “bump” into the invader.
- Specific response – This is when antibodies respond to the invading pathogen and is a process that involves the B cells. It is like a zooming device that will make the B cells get to the pathogen in record time.
- You don’t fall prey to every bug around
- You throw off infections quite easily
- You aren’t constantly itching or sneezing
- You generally feel well
If you have a fully functional immune system, then when you are exposed to a bug, you should kick it out quickly and symptoms such as a raised temperature will not last for long.
Weak immune function makes it harder to withstand infection by viruses, bacteria or fungi. You will be more susceptible to contracting colds, flu and cold sores. The immune system will take longer to detect and conquer the bug, so symptoms such as raised temperature, swollen glands, sore throat, coughs, catarrh, etc., will be present more frequently.
- Active immunity is gained by being previously exposed to the infective organism. An antibody is produced and then remains in the body ready to fight the same organism again.
- Passive immunity is transferred from mother to baby in a process that involves antibodies being passed to the baby in the womb and during the first few days of breastfeeding.
The immune system can be weakened by any combination of negative factors.
Existing on a bad diet, having a stressed lifestyle that causes you insufficient sleep and is not making you happy, and living in an area of high pollution such as a city, can be a perfect recipe for poor immune function.
People who work with the general public, in the health system or in schools often find that they become ill regularly until their immune system adjusts to the increased exposure to new “germs” or pathogens.
If you are falling prey to every bug that goes around, your immune system may not be detecting pathogens early enough to stop them before they cause trouble. Your T cells need to smarten up their act. If you have trouble throwing off a bug once it has hit you, your immune system may be incapable of launching an effective assault on the pathogen even after it has been detected. Your phagocytes need beefing up.
In certain circumstances, the immune system becomes confused and starts attacking the body’s own cells instead of bugs. This is known as an autoimmune condition.
When the immune system is confused and overworked, it may start reacting to things that are not a threat, over-responding to friendly antigens. This could give rise to allergies as the immune system becomes oversensitive and begins attacking randomly and “jumping at shadows”.
Histamine is often released by the immune system during allergic reactions and is responsible for the itch and redness that is observed. In allergic conditions, the immune system needs to be stabilized and desensitized.
There are many herbal remedies that work on the immune system. Some are unique in that no other form of (synthetic) medication is known to work in the same way.
An example is Echinacea, a herb that balances the immune system. Echinacea is known as an immunomodulator, strengthening the immune system when it is weak and working to balance immune function.