Have you ever noticed the connection between your immune system and your gut? Do you get sick often and have allergies or gut issues?
When conceptualizing immune function, it can be broken down into two parts. The innate immune system, the one we are born with and the adaptive immune system, the one the learns and gets smarter over time
You can think of the innate immune system as a set of instinctual immune responses and the adaptive immune system as a set of learned responses.
It’s much like our makeup of behavior. The innate immune system is a bit like a hand grenade, imagine the soldier holding the pin ready to release quickly and indiscriminately targeting anything in the area when time is of the utmost importance. Like when you have an open wound, there is no time to survey the land, the critical goal is to keep you alive and preserve your health. The innate immune system is triggered to quickly keep the area clean or rid it of infection. In the case of an open wound the body is exposed and the innate immune system instinctively knows that the area must be protected even if a few bystander healthy cells are injured in the process.
White blood cells are part of the innate immune system. Since this system is located alongside a physical barrier it takes a broad approach to defense that is not super strong because there are other mechanisms in place to keep out unwanted intruders such as acid and enzymes in the gut. Think of the innate immune system as an antibacterial hand wash generally cleaning out the area weeding out many of the bad guys.
Also, there are three major types of innate immune responses:
Phagocytes, or pathogen-eating cells
Natural killer cells
The innate immune system is key when it comes to allowing the body to act fast. Inflammatory cells kill invading pathogens by raising the body temperature to burn them off. Blood flow is increased, and a fever may occur all as a way to protect the body by becoming too hot to trot. Inflammation is a response that helps protect the body against unfriendly bacteria and supports tissue repair.
Similar to fight or flight inflammation is a necessary response that only becomes problematic when it goes on for too long or the reaction is too strong. Why would this happen? Well, for example, if you are eating a food that creates an immune reaction inflammation will occur to protect you from being irritated. It can also happen to protect you from harmful bacteria, makes sense, right?
For a long time, the common wisdom was that children should be put on antibiotics or medication to bring a fever down but now we are starting to understand the wisdom of letting a fever run its course and how a fever can be a sign of the body doing its job well.
Another way our body fights invaders is with Phagocytes. These are like little Pac man that go around gobbling up pathogens.
The third way the innate immune system works is by creating what are called natural killer cells. These cells target any cells that’s been overtaken by a virus or infection. When it is too late and the cell has already gone over to the dark side, the natural killer cells essentially pull the plug and kill off the cell to help restore the body. This is what is referred to as a changed body. It was once a normal cell but now that is has become infected for the good of the whole it is no longer safe to keep this changed cell around.
If this first round of defense isn’t successful about 4 to 7 days later the body unleashes it’s second round of attacks, the adaptive immune system. You can think of these defenders of the body as the sharp shooters that can target specific pathogens or cells. The adaptive immune system is smart, it has a memory of cells that have created a previous offense in the past, like a database of information. When a familiar threat is experienced the body can look in its storage for the perfect antidote or antibody to ward off that offender. The adaptive immune system knows its enemies’ weak points and uses that to formulate its strategy, cool right?
This is why it can be slower than the innate immune system, it’s calculated and if there is no memory stored it takes the body a while to figure out what to do. But previous offenders watch out, it’s got your number.
These memory cells are the reason that some illnesses like chicken pox tend to happen only once. Vaccines also work on this system. In a vaccine an active virus or bacteria that may cause illness are introduced so that the body is warned and can properly fight off infections when they are faced with them in the future.
In summary, we laid the groundwork by going over the two parts of the immune system. These are the innate and the adaptive immune systems. The innate system is the first responder beyond the gut wall, and it works to quickly protect the body by killing off whatever is around it. The next and smarter line of defense is the adaptive immune system which strategically uses its memory of past invaders to form its plan of attack.
Did you know that healthy bacteria can impact the immune system as well? In Part III we'll uncover that in addition to helping us digest even more of our food while also synthesizing vitamins, the bacteria in our gut are constantly communicating with the immune system by sending chemical signals that help determine what pathogenic bacteria have gotten out of line, or grown out of control. Stay tuned....