Prolonging the Lifespan of Neutrophils for Granulocyte Transfusion in Neutropenic Mice with Bacterial Pneumonia

Neutrophils act as the first line of defense in our innate immune system, executing essential antimicrobial functions to fight off pathogens. Neutropenia, which can occur due to defects in bone marrow granulopoiesis or treatments such as chemotherapy, significantly increases the risk of infections. To manage complications arising from neutropenia, standard treatments include granulocyte colony-stimulating factor (G-CSF) induction or granulocyte transfusion (GTX), along with standard antibiotic therapies. Here, we present a comprehensive method for inducing neutropenia in mice and using granulocyte transfusion to mitigate acute pneumonic inflammation. However, GTX faces challenges such as the short lifespan of neutrophils and the inability to freeze GTX products. We have previously developed a novel approach, CLON-G treatment, which combines the inhibition of multiple cell death pathways in neutrophils. This treatment extends the lifespan of neutrophils to over 5 days without compromising their essential functions. Our earlier findings suggest a promising strategy for enhancing the efficacy of GTX, improving neutropenia management, and strengthening immune responses against infections. Additionally, we describe a method for transfusing CLON-G-treated neutrophils to enhance host defenses against neutropenia-related complications, as demonstrated in an Escherichia coli-induced neutropenic pneumonia model.