45 Year old homeless man has chronic cough and cavitatory lesion of lungs. His sputum is positive for acid fast bacilli which of the following is the peripheral form of defense by which his body fights this infection -

Infection with the tubercle bacilli induces cell mediated immunity which manifests as delayed hypersensitivity and resistance to infection (immunity ). The only specific immune mechanism effective against tubercle bacilli is cell mediated type. The helper T cell gets activated, releasing cytokines such as interferon gamma, interleukin 1 and 2, toxic necrosis factor alpha that exes different biological effects. Reference : Anathanarayan & paniker's 9th edition, pg no:350 <\p>