Therapeutic effectiveness of rituximab in a patient with unresponsive autoimmune pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare lung disease characterised by the accumulation of lung surfactant in the alveoli. In most cases it is an autoimmune disease with antibodies directed against the growth factor granulocyte-macrophage colony stimulating factor (GM-CSF). Standard of care consists of whole lung lavages in symptomatic patients. An alternative treatment is GM-CSF injections. The case history is reported of a patient with PAP and severe dyspnoea and hypoxaemia. Whole lung lavages and GMCSF initially resulted in partial remission. However, the patient's condition deteriorated and her saturation during rest with high-flow oxygen treatment was 85%. The patient was treated with an anti-CD20 antibody rituximab which resulted in dramatic improvement. Room air saturation increased to 98% with exercise and she no longer required supplemental oxygen. The diffusion capacity for carbon monoxide increased from 27% to 48% of predicted and the chest x-rays improved. Rituximab may be useful in the treatment of patients with unresponsive PAP.