How does immune system work? Every second, million bacteria, virus, and fungus try to make a home for them. So our body develops a complex and tiny army as a protection, guard, memory, troops, weapon factory, and communication tool to protect us from death.

How does the Immune System Protect our Body?

To make it easy, we have 12 different immune system jobs. For instance, to kill bacteria, to communicate, etc. and there are 20 different cells and 2 proteins. These cells have 4 different jobs, let’s have a look at the picture. This is the interaction among the immune system. Now, let’s make it simple.

12 different immune system jobs

12 different immune system jobs
Picure: kurzgesagt

For instance, in a sunny day, suddenly a rusty nail hit your skin. The first immune system is skin. The nearest bacteria have an opportunity to get inside the body through the wound. They starts to use our body resources, and multiply every 20 minutes.

At first, they fly under the radar of immune system, but when those bacteria reached high number of  population, they change their behavior and damage our body by changing the environment around them. The immune system work very hard to stop them as fast as possible.

High number of bacteria alarms the body immune system

High number of bacteria alarms the body immune system
Picture: Kurzgesagt

Macrophages Role

First of all, our guard cells (macrophages) interfered. Macro phage is a big cell which guard every small part of our body. Sometime they can handle the attacks, it is because they can eat and destroy 100 bacteria. They eat the bacteria and trap them inside the membrane. The bacteria will break down into a small enzyme and be killed.

Macrophage first role

Macrophage first role
Picture: Kurzgesagt

Meanwhile, they initiate inflammation by sending fluid into the war so that the war is easier. In this condition, you will see a mild inflammation. When the macrophages fight too long they will call back up by sending messenger proteins that can tell the location and urgency.

Neutrophil Roles

Neutrophil is the strongest, they even can kill the healthy cells while they produce barriers that catch and kill the bacteria. They are very deadly, they can evolve to suicide after fighting. After 5 days, to prevent more damages, if the neutrophil cannot stop the invasion, the brain of immune system join the battle (Dendritic Cells)

Dendritic Cells

The dendritic cell is activated by the army signal and start collecting sample from the pieces of bacteria on the outer layer of dendritic cell. Now, the dendritic cell makes a crucial decision.

Dendritic Cell

Should it call antivirus or anti-bacteria army to kill the infected cells?
Picture: Kurzgesagt

In this case, anti-bacteria army is needed then travels from the closest lymph node for a day. There, millions of T- Cells and Killer Cells are waiting to be activated. When T cell is produced, they will pass the complex and complicated process, only ¼ are surviving. The surviving cells will have specific setup.

Memory Helper T Cell and Memory B Cell

Memmory Helper T Cell and Memmory B Cell

Memmory Helper T Cell and Memmory B Cell
Picture: Kurzgesagt

Dendritic cells will come to take T-cell with specific setup. It is looking for T-cell that can join the sample part of the enemy. While it is match, the chain reaction is about to happened. T-cell is activated, and multiplies thousand times. Some becomes T-memory cell that remain in lymph node, and make our body strong toward the recent bacteria. Some are going to the battlefield to help. And the third group will travel to the center of lymph node to activate powerful weapon factory.

Chain reaction of Dendritic Cell

Chain reaction of Dendritic Cell
Picture: Kurzgesat

Just like T-cells, B-cells have a specific setup. When specific B-cell and T-cell met, hell breaks loose! The B-cell multiplies rapidly and star to produce millions of little weapon. They works so hard so that they can die because of exhaustion very fast. Here T-cell plays important role, they stimulate exhausted B-cell and say, “Don’t die yet! We still need you, be strong and keep going!”

Small Weapon (Antibodies)

New T-cell will let B-cell die if the infection is over, so the body will not waste source of energy in our body. But, what was B-cell produced? You have heard them of course: Antibody, little proteins that are designed to bind specific bacteria. There are different antibody classes with different functions.

Antibody Classes

Antibody Classes
Picture: Kurzgesagt

T-cell informs plasma cells about what class of antibody is needed to end the invasion. Millions of them flood blood steam and travel around the body. Meanwhile the site of infection are getting worse, the guard and attacking cells fight hard, some are die in a process. T-cell helps them by ordering them to be more aggressive and stay alive longer. But without help, they cannot kill the bacteria.

The Second Body Protection

Now a second immune system is arrived. Trillions of antibodies flooded the battlefield and paralyzed the enemies by making them helpless and kill them. They also make the bacteria as an easy target. Then macrophages eat bacteria with antibody attached.

Now the balance shifts, in a team effort, the infection is wiped out. At this point millions of body cells have already died, the losses are quickly replenished. Most immune cells are now useless and without the constant signals they commit suicide, so as not to waste any resources.

But some stay behind: the memory cells. If this enemy is encountered ever again in the future, they will be ready for it and probably kill it before we even notice.

In Summary

This was a very simplified explanation of parts of the immune system at work. Can you imagine how complex this systems is, even at this level, when we ignore so many players all the chemistry.

Life is awfully complicated, but if we take the time to understand it, we will encounter endless wonders and great beauty.

Hold up! You also can watch the video source of Kurzgesagt, or you can read a related to immune system problem article: