The immune system is not something that sits at a specific place in the body; I cannot point to it or put my hand on it like I would on a sore tummy.
In a generally healthy body, not one like mine, the immune system is a well organised team of different cell types employed to destroy viruses and bacteria which try to attack the body from outside.
Imagine your body as a quiet little town of friendly neighbours where everybody knows each other. Obviously, sometimes it can get a bit noisy and restless when the virus gang or the bacteria boys come into town. That’s when the sheriff, the big helper cell, rings the alarm bells to call the posse. And everybody knows what to do: the phagocytes shoot without asking and clear away the dead bodies. They quickly put up wanted posters to warn the whole town about the attackers, while the good citizens start repairing the damage. The sheriff instructs his courageous team of killer cells to search all over town for any intruders trying to hide. Another group of the sheriff’s team, the plasma cells are also active right from the start, firing off a canon of powerful antibodies. So that the next time the gang comes into town, they get marked right away and are easy to eliminate. But sometimes the cowboys in the posse are a bit unruly and things get out of hand. That’s when the deputy steps in, the regulator cell. He calms everybody down. Usually, that is.
But there are also bad days, when the cowboys and the sheriff had too much to drink and start to run riot in town. And sometimes even the best deputy has enough of it and slinks away while all hell breaks loose.
My liver has started to complain, the lab work points to some unruly behaviour. The sheriff must be drunk again.