This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
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 - 
Select and explain. 
A. Antibody mediated, B. Cell mediated hypersensitivity, C. Ig A mediated hypersensitivity, D. Ig E mediated hypersensitivity
B: Cell mediated hypersensitivity
Answer: B: Cell mediated hypersensitivity 
Explanation: 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>