Susceptibility to Mycobacterium tuberculosis infection is not influenced by a pre-existing helminth infection

Mycobacterium tuberculosis is currently responsible for 8 million new cases of tuberculosis world-wide and 1.7 million deaths annually. The WHO estimates that 1.5 billion people in tuberculosis-endemic countries are also infected with helminths. The impact of helminths-infection on susceptibility to tuberculosis is incompletely understood, though. We have shown that T helper (Th) 2-associated induction of arginase-1 activity in macrophages subverts efficient elimination of M. tuberculosis. This indicated a role for alternatively activated macrophages (AAMs) in undermining protective anti-tuberculosis effector me…