Purinergic Signaling: A Common Path in the Macrophage Response against and .

Immune responses are essential for the protection of the host against external dangers or infections and are normally efficient in the clearance of invading microbes. However, some intracellular pathogens have developed strategies to replicate and survive within host cells resulting in latent infection associated with strong inflammation. This excessive response can cause cell and tissue damage and lead to the release of the intracellular content, in particular the nucleotide pool, into the extracellular space.

Ecto-5'-Nucleotidase (CD73) Deficiency in Mycobacterium tuberculosis-Infected Mice Enhances Neutrophil Recruitment.

The immune system needs safeguards that prevent collateral tissue damage mediated by the immune system while enabling an effective response against a pathogen. The purinergic pathway is one such mechanism and finely modulates inflammation by sensing nucleotides in the environment. Extracellular ATP is considered to be a danger signal leading to a proinflammatory response, whereas adenosine is immunosuppressive.

Extracellular adenosine triphosphate affects the response of human macrophages infected with Mycobacterium tuberculosis.

Granulomas are the hallmark of Mycobacterium tuberculosis infection. As the host fails to control the bacteria, the center of the granuloma exhibits necrosis resulting from the dying of infected macrophages. The release of the intracellular pool of nucleotides into the surrounding medium may modulate the response of newly infected macrophages, although this has never been investigated.