Discovery of a mechanism of immunity suggests there
may be a better way to protect vulnerable children against Streptococcus pneumoniae infection. Researchers at Children's and Harvard School of Public Health have been studying how natural pneumococcal immunity develops, and now show that in addition to antibodies,
a group of T-cells known as TH17 cells block nasal
colonization, providing broader protection.
The research, led by Richard Malley, MD, of Children's Division of Infectious Diseases, shows that most adults and older children have TH17 cells that target
pneumococci, but that newborn babies do not,
suggesting pneumococcus exposure leads to the cells' production. Dr. Malley demonstrated this in mice and showed that the TH17 cells release IL-17, a cytokine that facilitates killing of pneumococcus in the nose, thereby shortening the duration of nasal carriage.
The findings, published in PLoS Pathogens on Sept. 19, may aid the development of novel pneumococcal vaccines. "We're now evaluating vaccine candidates and changing them so they induce this specific type of immunity," says Dr. Malley.
Dr. Malley's lab is developing an inexpensive whole-cell vaccine that elicits a robust TH17 response in mice. It will soon be manufactured for human testing. If effective, it would offer the advantage of broad protection against all strains, unlike the existing vaccine, Prevnar, which covers seven of the 91 known serotypes. "A vaccine that induces both protective antibodies and T-cell immunity may be a very effective way to protect against pneumococcal disease," says Dr. Malley.
More information: childrenshospital.org/malley