Macrophages can adapt immune responses based on past infections

Researchers at the University of Chicago have discovered a new type of immune memory involving macrophages, which are a kind of white blood cell. This finding could lead to new treatments for infections and autoimmune diseases. Traditionally, antibodies were thought to be the main players in immune memory. They help the body remember past infections. However, the study found that macrophages also adapt their responses based on previous encounters with pathogens. This means they can become either more tolerant or more responsive during subsequent infections. The study’s authors used a high-tech approach to test how macrophages react to different bacterial and viral signals. They discovered that exposure to certain inflammatory signals could either "prime" macrophages to respond more aggressively or lead to "tolerance," making them less responsive to future threats. The researchers found that higher doses or prolonged exposure to pathogens generally increased tolerance. In addition, the team noticed that macrophages taken from mice with sepsis showed weaker immune reactions. This may explain why sepsis patients are prone to secondary infections. The researchers suggest that enhancing macrophage activity could help in treating sepsis. The scientists also developed a machine-learning model that predicts how macrophages will react based on their previous exposures. This breakthrough could have practical applications in understanding inflammatory responses. Current findings only cover a short time frame of about 12 hours, but scientists think that changes in macrophages may persist for days or weeks. More research will be needed to confirm this.