Final answer:
The primary infection of Mycobacterium tuberculosis is mainly controlled by the development of activated macrophages in the host, as the bacterium's protective mycolic acid coat allows it to resist other immune responses.
Step-by-step explanation:
The control of the primary infection of Mycobacterium tuberculosis is most likely the result of the development in the host of activated macrophages. This is because M. tuberculosis is able to evade the immune system using its waxy mycolic acid cell wall which makes it impervious to polar molecules, allowing it to grow slowly and survive inside macrophages. A TH1-mediated immune response later activates the macrophages, allowing them to overcome the bacterium's defenses and destroy it. Unlike other bacteria that can be neutralized by antibodies binding to their antigens, M. tuberculosis requires this cellular immune response for effective control. The importance of activated macrophages in controlling M. tuberculosis can also be evidenced by the tuberculin skin test, which detects a cellular immune response to the bacterium.