If these were people then they would be ninja's. These are our warriors that track and kill anything that is in our body that shouldn't be. This is the Giant Microbes White Blood Cell Leukocyte and without these you would surely die very very young.
Any idea how many of these you have? Well, I can tell you because we have just Googled it, we have 25 trillion of these kung fu fighters. That is by far the largest army in any known world. Surprisingly these are made in the bone marrow and that is why when you hear of people needing a bone marrow transplant it is because the 25 trillion strong army has declined.
These carry out their duty day in and day out and we don't even know they are doing it. Ask yourself, when was the last time you thanked your white blood cells?
Well, here he (or she) is. In all of its Giant Microbe glory.