In the July 2 issue of the Journal of Clinical Investigation, Adrian Martineau, Robert Wilkinson, and colleagues from the Wellcome Trust Center for Research in Clinical Tropical Medicine in London report that the activity of white blood cells known as neutrophils is one reason why some individuals exposed to the infectious bacterium Mycobacterium tuberculosis resist developing evidence of tuberculosis (TB) infection for longer than their peers.
The authors studied 189 adults in London that had been in contact with TB and evaluated them for evidence of TB infection. They found that the risk of TB infection was inversely associated with the number of peripheral blood neutrophils in exposed individuals.
The ability of whole blood that lacked neutrophils to restrict the growth of M. tuberculosis was impaired 3-fold. The authors went on to show that the neutrophil peptides cathelicidin LL-37 and lipocalin-2 restricted growth of the organism. Together, the data indicate that neutrophils substantially contribute to the innate resistance of an individual to M. tuberculosis infection, and this activity is associated with neutrophil antimicrobial peptides. Further work to identify how these antimicrobial peptides are regulated may facilitate prevention and treatment of TB.
TITLE: Neutrophil-mediated innate immune resistance to mycobacteria