The body has a veritable army constantly on guard to keep us safe from microscopic threats from infections to cancer. Chief among these forces is the macrophage, a white blood cell that surveils tissues and consumes pathogens, debris, dead cells, and cancer. Macrophages have a delicate task.
It's crucial that they ignore healthy cells while on patrol, otherwise they could trigger an autoimmune response while performing their duties. Researchers at UC Santa Barbara sought to understand how these immune cells choose what and when to eat. A paper in describes how the team programmed macrophages to respond to light in order to investigate how encounters with cancer cells change the macrophages' appetite.
"We discovered that giving macrophages an appetizer makes them hungrier for their next meal," said senior author Meghan Morrissey, an assistant professor in the Department of Molecular, Cellular, and Developmental Biology. The results present a new way to increase the effectiveness of cancer immunotherapies that harness macrophages to combat the disease. It also offers a more complex account of trained immunity, a kind of memory exhibited in the innate immune system that scientists have only recently recognized.
Using light to control the cellular appetite While monitoring the body, macrophages scout for cells and debris tagged with the antibody IgG by other . These function as "eat me" signals to the macrophages, which detect them via Fc receptors (FcR) embedded in their cell me.