The basis for INSIGHT-AM came from previous work conducted by our PRINCIPLE research group (Paediatric, Respiratory and INtensive Care Immunity and PuLmonary Epithelium group), and by the desire to address a gap within the relevant literature. Most of our group's work involves innate immunity, and immune dysfunction, often within the context of respiratory or critical illness. We have previously used Sargramostim (recombinant human GM-CSF) as an injectable medication for carefully selected groups of critically ill individuals with immune dysfunction. We are now exploring its effects on a key immune cell of the lung called the Alveolar Macrophage (AM) with the longer term goals of developing clinical trials that may help treat or prevent pneumonia and respiratory infections in the most vulnerable individuals, and to support the antimicrobial stewardship programme by developing interventions that can reduce our over-dependence on antibiotics.