Immunopathogenesis of tuberculosis. The M. tuberculosis infection begins with the inhalation of airdrops that contain numerous bacilli that are phagocytosed. The initial stages of infection are directed by cells responsible for innate immunity, and the recruitment of inflammatory cells leads to the formation of an early granuloma. Antigen-presenting cells migrate to nearby lymph nodes and activate lymphocytes that return to the lung and generate the mature granulomas. The immune system contains the primary infection in almost 90% of patients, who will develop latent tuberculosis.