When an outside pathogen enters our bodies, our immune system responds with its army of white blood cells and antibodies. But who sends out the marching orders to this network?
A certain kind of immune cell called a dendritic cell sends out the initial call, scientists and engineers have learned. But many in the field have debated just how these cells do this. Do they all send out signals simultaneously? Or does a smaller group reach a consensus and then tell the others what to do, like social media influencers?
To find out, Assoc. Prof. Aaron Esser-Kahn and his team in the Pritzker School of Molecular Engineering (PME) at the University of Chicago isolated these dendritic cells in a mouse model and found that a small subset act as “first responders,” gathering information and signaling to other cells to respond.
They also found out just how important these cells are to immune response. When the signaling ability of these first responders is removed, the whole communication network collapses, and the immune system does not respond at all. “These first responder cells aren’t just influencers—they have a level of control that hasn’t been appreciated before,” Esser-Kahn said.
The results, which could have implications for vaccine design and autoimmune disease therapy, were published in Cell Reports.
First responders emerge from dendritic cell population
Esser-Kahn and his group began to study this phenomenon after they noticed an interesting result while researching vaccine adjuvants, ingredients added to vaccines to elicit a stronger immune response. They found that a large amount of these adjuvants ended up in a small percentage of dendritic cells.
Esser-Kahn’s team studied the cells and found signature proteins on their surface, allowing the team to easily identify and isolate the cells for more direct study.
What the team found surprised them. These dendritic cells weren’t like the others. A small subset—about 5 percent—had taken on new characteristics that allowed them to identify the invader—in this case, a vaccine administered by the team—and begin alerting other cells. These abilities only lasted for a short time, about 30 minutes.