Modelling the human immune response mechanisms to Mycobacterium tuberculosis infection in the lungs

This work elaborates on the erects of cytotoxic lymphocytes (CTLs) and other immune mechanisms indetermining whether a TB-infected individual will develop active or latent TB. It answers one intriguing question: why do individuals infected with Mycobacterium tuberculosis (Mtb) experienced different clinical outcomes? In addressing this question, we have developed a model that captures the effects of CTLs and the combined erects of CD4+ helper T cells (Th1 and Th2) immuneresponse mechanisms to TB infection. The occurrence of active or latent infection is shown to depend on a number of factors that include effector function and levels of CTLs. We use the model to predict disease progression scenarios, including primary, latency or clearance. Model analysis shows that occurrence of active disease is much attributed to the Mtb pathogen ability to persist outside the intracellular environment and that high levels of CTLs result in latent TB, while low levels of CTLs result in active TB. This is attributed to the CTLs' ability to directly kill infected macrophages and the bacteria inside the infected macrophages. The study suggests directions for further basic studies and potential new treatment strategies.