<prompt> 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 -Antibody mediatedCell mediated hypersensitivityIg A mediated hypersensitivityIg E mediated hypersensitivity  <response>: 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 panikers 9th edition, pg no:350 p 