Scientists accelerate immune response to tuberculosis

WASHINGTON, Dec. 22 (UPI) -- Researchers have found that by activating certain immune pathways they can accelerate the immune response to tuberculosis.

There were an estimated 10.4 million new TB cases worldwide in 2015, according to the World Health Organization.

A recent study by scientists at Washington University in St. Louis, Mo., worked to created a improved TB vaccine for adults.

A TB vaccine called bacille Calmette-Guerin, or BCG, is currently used in countries with high instances of TB to prevent severe forms in children. In adults, however, the vaccine is very variable at providing immunity against pulmonary TB and often shows false positives on skin tests.

Using laboratory mice, scientists found that during an infection with the TB bacterium Mycobacterium tuberculosis, immune system cells, called T cells, are slow to develop in the lungs and attack the disease, allowing the infection to develop despite vaccination.

For this study, scientists examined whether the delay in immune response could be prevented by activating certain immune pathways using dendritic cells. They did this by establishing that T cells from vaccinated mice were able to respond well to TB bacteria, then they introduced dendritic cells that present molecules from diseased cells to disease-fighting T cells prompting the T cells to attack.

Researchers used the dendritic cells that had already been "primed" by exposure to TB bacteria into the lungs of vaccinated mice, and exposed the mice to different strains of Mycobacterium tuberculosis. In doing this, the researchers found that the vaccinated mice that received activated dendritic cells at the time of infection achieved near-sterilizing levels of immunity against TB.

The technique used in mice may be difficult to replicate in humans because activated dendritic cells need to be applied at the time of infection, which is hard to determine in humans.

The results of the study have led to a better understanding of the components of TB immunity and could shape the direction of TB vaccine research in the future.

The study was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, and was published in Nature Communications.