The National Institutes of Health recently awarded $2.2 million to Alissa Rothchild, assistant professor in the Department of Veterinary and Animal Sciences at the University of Massachusetts Amherst and an expert in tuberculosis (TB) immunology, to study the very first cells that respond to Mycobacterium tuberculosis (Mtb), the bacteria causing TB. How those initial cells, known as alveolar macrophages, or AMs, respond to the bacteria is not entirely known, though Rothchild and her lab have shown in a previous study that AMs don't respond to Mtb infection the way other macrophages do.

Instead of mounting a strong inflammatory response, AMs turn on a cell-protective program that favors their survival over robust activation. Studies from the Rothchild lab and others have shown that AMs also have the capacity to be reprogrammed to mount a more robust response under different conditions. Rothchild and her colleagues will be spending the next five years trying to do just this.

To understand how Mtb infects the body, it's useful to first think about immunity. And when we think of immunity, we typically think of the adaptive immune system, which is when prior exposure to a pathogen -; either from a previous infection or from vaccination -; teaches the immune system what to guard against. While the adaptive immune system is very effective, it is not the body's first responder -; that is the job of the innate immune system and its ranks of macrophages.

Macrophages are the firstline d.