No matter, who we are, where we live, or what we do, whether we will live a healthy or a debilitated life depends solely on the health of our immune system. The system that protects our body and helps us be to be healthy.
We might have different priorities in our life but for our immune system there is only priority come what may protect the body and that's the reason it is the last system in the body to switch-off.
The immune system works through a combination of multi-celled, interrelated, and interdependent activity, the cytokine environment, which determines how immune cells respond. Without a properly functioning immune system, you’re susceptible to disease. A more fully functional immune system will aid the body in eliminating almost any disease.
Cytokines are easily damaged in today’s environment. Cytokines are damaged or destroyed through a number of ways and without them, your immune system can’t respond or doesn’t respond properly, as is the case with autoimmune diseases. 
The Immune system is a very effective system and a more powerful system than you can imagine. It’s the reason you can live in a world that has always had tiny foreign things; bacteria, viruses, parasites, yeast, etc. trying to use our body as a new “home”. Add to this a number of other problems the immune system has to contend with and you’ve got one busy system overwhelmed with work. 
If You Get Sick Your Immune System Doesn’t Care What Name You Call It
If those threats in the form of infections or inflammations are successful, you get sick. If not, you might not notice, or hardly notice that a battle has been waged and you won – which actually goes on constantly. If you do get sick (and your immune system doesn’t care what name you call your illness) you expect to recover. And you do, as long as your immune system has the brains and brawn to do the job. Your immune system keeps you healthy. 
Each Kind of Cell Has A Specific Job To Do
The immune system is spread out over your entire body. It’s not an organ or any kind of stationary mass. It has many different kinds of cells, each with its own job to do. These cells come from your bone marrow. Some cells get special training to understand their job and they get this in the thymus gland. Some are “born” knowing what to do. The cells make a choice about what kind of immune cell they’re going to be when they “grow up” however no one seems to have a “for sure” idea about how they do that. There are many other associated immune factors as well. It’s a complicated system and one that the most advanced researchers still don’t fully understand. 
An Interdependent System
There are lots of different immune cells and they’re dependent on one another to work because they have different jobs to do. Some immune cells kill viruses and cancer cells directly like Natural Killer cells. They know what to do and they just do it, if all is well. Others, like T-cells, are even more deadly in their power but are slower to react and need help in identifying who and where in your body the problem might be. They need other special cells that “help” them like B-cells for instance. The Macrophage is another cell. It’s very good at killing bacteria and cleans up any kind of “garbage” it comes across. It’s a good “siren” for danger as well. If there’s not something serious going on, it spends a lot of time just ambling through your body gobbling up whatever “foreign thing” it bumps into.  
Cells Must Communicate And They Do It With Cytokines
Since the immune system is made up of lots of different kinds of cells spread out all over, and, since they depend on each other, they absolutely must communicate. And they do.  They communicate with things called cytokines. They’re also called communication or messenger molecules. These are little hormone-like proteins. They tell immune cells to grow in number, they tell them where the action is, and they tell them when the enemy has been destroyed among other things. 
“Pathways” of communication are made between immune system cells. If it can, each kind of immune cell generates a certain specific cytokine(s). 
Without Cytokines Your Immune System Is Deaf, Dumb, And Blind
These cytokines are pretty important because the immune system can’t respond without them and the choice made by immune cells depends on them.  Your immune system might not know anything was going on, or what to do about it if it did, or would respond incorrectly. 
You may have heard of interleukins or interferons? They’re cytokines; communication molecules. Your immune cells could be as happy as can be but without those cytokines giving direction your immune cells are clueless. How, and if, the immune system responds depends on the cytokine “environment”. 
Immune Systems Weaken With Age But You’re Still Making Lots Of Immune Cells So What’s The Problem?
You’ve probably heard that the immune system weakens as you age. However, we produce the same amount of immune cells (in bone marrow) when we’re very old as we did when we were young. Barring damage to your bone marrow (chemotherapy for instance), it’s likely you’re still producing immune cells in good numbers! 
If that’s true, then why cancer, and viral infections, and bacterial infections, and autoimmune disease and chemical intolerance, and the seemingly hundreds of diseases chronically plaguing people today? And why does your immune system weaken as you age if you’re still producing immune cells in good numbers? There have to be other reasons.  
Reasons for Poor Immune Function: Drains And Stressors
Those “other reasons” are related to the times we live in. Each of these potential problem areas can affect hundreds of functions and many organs in your body, but they also affect the immune system.  They can destroy cells and wipe out cytokines (communication). They are stressors and drain on immune function. Stressors and Burdens are,
- Poor nutrition 
- Poor digestion 
- Lack of essential fatty acids
- Stress
- Hormone imbalance
- Free radicals 
- EBV, CMV, and HIV 
- Antibiotic overuse
- Radiation 
Stop The Revolving Door Of Immune System Damage
Paying attention to these “Stressors and Burdens” can’t in and of itself replace cytokines but it can help stop the revolving door of immune support. 
A Dysfunctional Immune System Will Eventually Get A Name
You won’t know your immune system isn’t working because the immune system doesn’t have any nerves (pain) to tell you something’s wrong. The symptoms you’ll get will be the result of whatever illness your immune systems’ lack of function finally becomes. 
This Drug, That Drug And This Other Drug
Conventional medicine says if you have this “label” or symptom, take this drug. Or more likely, this drug, that drug, and this other drug. Sometimes it’s necessary. Drugs stimulate or depress one activity in your body. That’s what they’re supposed to do. Unfortunately, other activities get stimulated or depressed unintentionally and those are called side effects. Antibiotics have their own issues, as do antivirals.
Supporting Immune Function Will Support Just About Everything
Everything in your body is interrelated. The idea behind health “naturally” is to raise your entire level of functioning by supplying those things your body needs.