Quantitative Analysis of Longitudinal Response to Aerosolized Granulocyte-Macrophage Colony-Stimulating Factor in Two Adolescents With Autoimmune Pulmonary Alveolar Proteinosis

BackgroundAutoimmune pulmonary alveolar proteinosis (APAP) is characterized by autoantibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF) in blood and tissues, resulting in alveolar surfactant protein accumulation. Patients with APAP present with ground-glass opacities (GGOs) and interlobular septal thickening on thin-slice chest CT scans. Aerosolized GM-CSF therapy (aeroGM-SCF) has qualitatively improved the clinical condition of patients with APAP. This report details quantitative chest CT responses to aeroGM-CSF.MethodsTwo adolescent patients (aged 16 and 19 years) with APAP were treated with aeroGM-CSF. Clinical parameters, including pulmonary function tests and chest CT scans, were obtained before and after aeroGM-CSF therapy. To evaluate the effect of the therapy, serial chest CT scans were analyzed using a novel approach permitting quantitative assessment of improvement in GGOs, lung weight, and gas volume.ResultsIn association with GM-CSF treatment, nutritional status and pulmonary function improved. Quantitative analysis of the CT scans demonstrated reduction in GGOs and lung weight, concomitant with an increase in airspace volume and lung inflation. The findings were consistent with a qualitative reduction in GGOs on chest CT imaging.ConclusionsQuantitative analysis of CT holds promise as a sensitive diagnostic tool permitting longitudinal and objective analysis of the therapeutic response to aeroGM-CSF in patients with APAP.