Our immune system manufactures them when they are actually needed.
Our bodies rise to the occasion if there actually is one.
Yes. VDJ recombination provides for continuos production of cells that recognize specific molecular shapes and when encountered the cell proliferates greatly.
That’s the initial immune response. These cells once selected and amplified remain after the infection has been eradicated, at lower levels that are still critically high enough for ready amplification if they encounter the same antigen again.
The innate immune system is the body's first line of defense against germs entering the body. It responds in the same way to all germs and foreign substances, which is why it is sometimes referred to as the "nonspecific" immune system. It acts very quickly: For instance, it makes sure that bacteria that have entered the skin through a small wound are detected and destroyed on the spot within a few hours. The innate immune system has only limited power to stop germs from spreading, though.The innate and adaptive immune systems, July 30, 2020The adaptive immune system takes over if the innate immune system is not able to destroy the germs. It specifically targets the type of germ that is causing the infection. But to do that it first needs to identify the germ. This means that it is slower to respond than the innate immune system, but when it does it is more accurate. It also has the advantage of being able to "remember" germs, so the next time a known germ is encountered, the adaptive immune system can respond faster.
This memory is also the reason why there are some illnesses you can only get once in your life, because afterwards your body becomes “immune.” It may take a few days for the adaptive immune system to respond the first time it comes into contact with the germ, but the next time the body can react immediately. The second infection is then usually not even noticed, or is at least milder.