how the immune system works?

Have you ever wondered why we struggle with fever, runny nose or skin redness? 

These are natural immune responses by the body for healing to take place. For example, having a fever might be uncomfortable, yet it is needed to destroy the invader as well as boosting the functionality of our immune cells. 

Let's travel back in time....

In the 19th century, Louis Pasteur came up with The Germ Theory which proposed the idea of germs being the sole cause of diseases. In response, pasteurization, antibiotics, and vaccinations were born. Saint Antoine Bechamp went against this assumption and advocated The Cellular Theory. This theory suggests that if the body is compromised then diseases will develop. Bechamp's theory advocates that a strong immune function can be achieved through healthy food choices and lifestyle. Needless to say, I sympathise with Bechamp's theory:)

 

We are all born with some immunity. This is known as the inborn immunity and it is functioning just like an army. Protecting our land, day in and day out. Overtime the army may get overwhelmed and more serious illnesses come about. Immunity is a very complex defence mechanism! There is ongoing research still to identify all the immune cells we own. What we presently know is that there are 3 lines of defences. Each line is cleverly pre-programmed to think for itself. So some of them are programmed to react to SPECIFIC pathogens while others attack ANY potential (non-specific) invaders. 

 

Let me walk you through the 3 lines of defences. 

The first and second lines are non-specific. These defences do not develop immunological memory but strike at everything they see foreign. The third line has specificity and memory. 

 

FIRST LINE DEFENSE

SKIN

The very first organ that comes into contact with the world is the  SKIN. Shedding, sweating and sebum production are ways to remove bacteria and inhibit their growth. The skin has an acidic PH, functioning as a protection mechanism aginst harmful bacteria. The skin and large intestine share some similarities, they are both home to beneficial microorganisms. That's why you may have heard from your grandparents that showering too often is unhealthy. It really strips the skin of good bacteria.

 

Scientists have confirmed that we have 10 times more bacterial cells than human body cells. Yes! You heard that right, we cannot exist without them. Modern lifestyle alters the community of beneficial bacteria living on our skin and potentially even turn them into harmful ones.

 

MUCUS

Mouth, airways, stomach, intestines, anus, vulva, and the eyelids are all protected by mucus. It is a sticky fluid lining the body cavities. Its main purpose is to destroy bacteria and traps particles such as dust and dirt. 

 

SECOND LINE

This level is much more sophisticated. It made up of various protein complexes. Each protein complex equipped to deal with different things, for example, the regulation of iron levels. Tight control is necessary for iron metabolism as too much iron likely to promote microbial growth.

 

Inflammation (acute), fever and natural killer cells are all working at this level representing non-specificity.

  • What is inflammation? Natural immune response to heal and repair the body

  • What triggers inflammation? Physical injury, tissue damage, and infection. 

  • What happens during inflammation?

  • White blood cells attack foreign invaders or perceived foreign invaders. 

  • Where inflammation occurs? Anywhere, really.  

FEVER

Why do we have fever and why we shouldn’t suppress a mild fever? Fever is actually a sign our immune system is fighting off an infection. It inhibits the growth of microbes, it helps the white blood cells to do their job better, it makes anti-viral proteins to be more effective and generally speeds up recovery time. Suppressing it may result in the body's temperature to drop to a level that stops these defence mechanisms from happening.

There are guidelines as to when it is advisable to stop the fever: 

https://www.mayoclinic.org/diseases-conditions/fever/in-depth/fever/art-20050997

 

NATURAL KILLER CELLS

They are a type of white blood cells with no immunological memory. They attack anything they consider foreign rather than being selective about what to kill. They reside in the blood, lymph nodes, spleen and the bone marrow.

 

The initial response to injury and infection are taken care of by the first and second lines of defences.

 

THIRD LINE

This line refers to our acquired immunity. Made up of B and T lymphocytes. 

 

B lymphocytes originate from the bone marrow and also mature there. They produce antibodies that destroy the invaders. 

 

T lymphocytes are more diverse than B lymphocytes. They mature in the thymus gland, not in the bone marrow. Some of them simply assist in destroying the invaders while others release toxic substances to deactivate the intruders. Additionally, suppressor cells exist to turn off the immune response once no longer needed to prevent excessive reaction that may lead to auto-immunity.

 

SPECIFICITY, MEMORY and TOLERANCE describe both the T and B lymphocytes. 

 

What does this mean?

 

  • Specificity means the lymphocytes are equipped with unique receptors to target one type of invader. 

  • Memory is formed after the first date with a specific invader. Future exposures to the same invader will be dealt with much faster and more powerfully.

  • Tolerance refers to not having a go at our own body cells. The white blood cells can be over-enthusiastic at times; regulating them is vital.

 

Our body cells carry a board saying hey ‘I am self’. This board should be recognised by the patrolling lymphocytes. If that fails, autoimmune disorders develop. 

 

Before my studies, I thought that the immune system is a completely different entity from other body systems. Here is the thing, about 70% of the immune cells live in our gut. They called gut-associated lymphoid tissue. This is where most of the lymphocytes reside. The remaining ones are located in the lymph nodes.

© 2020 Anita Andor