A study published on September 12th by the journal Immunity ties together two emerging areas of HIV vaccine research. In recent years, scientists have discovered that a small proportion of chronically infected individuals develop antibody responses capable of broadly neutralizing a diverse array HIV isolates. These antibody responses typically take years to develop, and are not present at sufficient titers to offer noticeable benefit to the infected individuals they are isolated from, but there is reason to believe that if they could be induced by a vaccine they could protect uninfected people against HIV acquisition. A potential complement to this line of investigation has been the discovery of T follicular helper cells (Tfh), a specialized CD4 T cell subset that plays a critical role in providing help to B cells, thereby facilitating antibody production. Researchers have posited that Tfh may have an important role in the generation of broadly neutralizing antibodies against HIV, but direct evidence has been lacking.
In the Immunity paper, Michela Locci and colleagues report that there is a circulating population of Tfh that can be identified using a combination of surface markers, and that in a large cohort of HIV-positive individuals the frequency of these cells correlated with the development of broadly neutralizing antibodies against HIV. The data suggest that inducing this type of Tfh response should be a goal for vaccines aiming to create neutralizing antibodies against HIV (or potentially any other pathogen).
In a helpful example of kismet, the September 13th issue of the journal Science featured an article by Jon Cohen describing progress in discovering broadly neutralizing antibodies to HIV, along with a review on the same topic and a podcast interview with the senior author of the review, Michel Nussenzweig.
Richard Jefferys is the coordinator of the Michael Palm HIV Basic Science, Vaccines & Prevention Project Weblog at the Treatment Action Group (TAG). The original blog post may be viewed here.