Earliest feature of TB:-

(C.) - Ingestion of mycobacterium tuberculosis inside the lung will cause stimulation in the no. of lymphocytes, that will cause lymphocytosis First cell in the lung which will be affected by myco. TB infection is alveolar macrophage Transmission of myco. TB - cough & sneeze (droplet infection) (A.) - TB infection is characterized by type 4 hypersensitivity reaction Type 4 hypersensitivity reaction- granuloma formation - LANGHAN's CELL (B.) - Langerhan's cell - giant cell found in the skin. (D.) - type of necrosis seen in TB is CASEOUS NECROSIS.