Amazing stuff! Why does the immune system respond so slow to an infection with TB?
"Tuberculosis kills about 1.5 million people worldwide each year. Among infectious diseases, it’s currently second only to COVID-19 as a cause of death. ...
there are many unanswered questions about the infection, including why it can linger in the body for months or years. Now, in a study conducted on monkeys ... researchers find that a key subset of infection-fighting immune cells only become fully active three months after the body first encounters Mtb, with a second subset of these cells emerging five months postinfection. The results suggest that a delayed adaptive immune response might be crucial to Mtb’s ability to establish a foothold in a host. ...
“That [the] TB immune response is unusual compared to other pathogens had been known for years, but people still don’t really understand why,” ...
Researchers have found that Mtb is equipped with an arsenal of tools that allow it to escape the immune response, often leading to latent TB with the formation of secondary granulomas that consist of infected macrophages surrounded by immune cells “guards.” The bacteria within those structures sometimes become reactivated months or years later if the immune system weakens due to immunosuppressive therapies or disease. ..."
there are many unanswered questions about the infection, including why it can linger in the body for months or years. Now, in a study conducted on monkeys ... researchers find that a key subset of infection-fighting immune cells only become fully active three months after the body first encounters Mtb, with a second subset of these cells emerging five months postinfection. The results suggest that a delayed adaptive immune response might be crucial to Mtb’s ability to establish a foothold in a host. ...
“That [the] TB immune response is unusual compared to other pathogens had been known for years, but people still don’t really understand why,” ...
Researchers have found that Mtb is equipped with an arsenal of tools that allow it to escape the immune response, often leading to latent TB with the formation of secondary granulomas that consist of infected macrophages surrounded by immune cells “guards.” The bacteria within those structures sometimes become reactivated months or years later if the immune system weakens due to immunosuppressive therapies or disease. ..."
From the abstract:
"Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is a global health concern, yearly resulting in 10 million new cases of active TB. Immunologic investigation of lung granulomas is essential for understanding host control of bacterial replication. Here, we identify and compare the pathological, cellular, and functional differences in granulomas at 4, 12, and 20 weeks post-infection in Chinese cynomolgus macaques. Original granulomas differ in transcription-factor expression within adaptive lymphocytes, with those at 12 weeks showing higher frequencies of CD8+T-bet+ T cells, while CD4+T-bet+ T cells increase at 20 weeks post-infection. The appearance of T-bet+ adaptive T cells at 12 and 20 weeks is coincident with a reduction in bacterial burden, suggesting their critical role in Mtb control. This study highlights the evolution of T cell responses within lung granulomas, suggesting that vaccines promoting the development and migration of T-bet+ T cells would enhance mycobacterial control."
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