Histogram showing the frequency distribution of serum GM-CSF autoantibody levels in healthy subjects (, n = 72), patients with PAP with active lung disease (■, n = 21), and patients with PAP in clinical remission of the lung disease (□, n = 2). Clinical remission was defined as formerly diagnosed patients with PAP who were currently presenting no respiratory insufficiency and had normal chest X-ray images. The range of serum GM-CSF autoantibody levels separating subjects with no or active lung disease from those without active disease is indicated (10.4-19 μg/mL, ▨).