Stress can interact with immune cells and regulate how they respond to allergens, causing physical symptoms and disease, a study has found. Published in the Journal of Leukocyte Biology, the study showed how a stress receptor, known as corticotropin-releasing factor (CRF1) can send signals to certain immune cells, called mast cells, and control how they defend the body. For the study, researchers from the Michigan State University (MSU) in the US compared the histamine responses of mice to two types of stress conditions - psychological and allergic - where the immune system becomes overworked. One group of mice was considered "normal" with CRF1 receptors on their mast cells and the other group had cells that lacked CRF1. "While the 'normal' mice exposed to stress exhibited high histamine levels and disease, the mice without CRF1 had low histamine levels, less disease and were protected against both types of stress," said Adam Moeser, from MSU. "This tells us that CRF1 is critically involved in some diseases initiated by these stressors," Moeser said. The CRF1-deficient mice exposed to allergic stress had a 54 per cent reduction in disease, while those mice who experienced psychological stress had a 63 per cent decrease. The results could change the way everyday disorders such as asthma and the debilitating gastrointestinal symptoms of irritable bowel syndrome are treated. "This work is a critical step forward in decoding how stress makes us sick and provides a new target pathway in the mast cell for therapies to improve the quality of life of people suffering from common stress-related diseases," said Moeser.