There is the innate immune system, the body's first line of defense, which is 'always on', and does not use antibodies. It is the adaptive immune system that p

There is the innate immune system, the body's first line of defense, which is 'always on', and does not use antibodies. It is the adaptive immune system that produces antibodies for a specific antigen - I guess for very mild infections the innate immune response is sufficient, and the adaptive never gets triggered.