Mechanism of reactive neutropenia (IMAGE) Hokkaido University Caption Under normal conditions (steady state) neutrophils regulate the gut microbiota. When the number of neutrophils drops (neutropenia), the composition of the gut microbiota changes, stimulating T cells to produce IL-17A. IL-17-A in turn stimulates the production of neutrophils in the bone marrow (reactive granulopoiesis). (Image: Daigo Hashimoto). Credit Daigo Hashimoto Usage Restrictions This image is copyrighted, but may be used to report on this press release if credited as instructed. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.