Figure 4

Semiquantitative estimation of the lavage protein content by measurement of its absorption at 405 nm for each 500 ml or 1000 ml portion lavage fluid fro all PAP patients (J01 – J04, A01 – A06) and the patient with cholesterol pneumonitis. a: Relationship of protein concentration and absorption at 405 nm of lung lavage fluid. There was a significant correlation between protein concentration assessed in the lavage with the Bradford assay and the absorption directly measured in the photometer. b: Zoom in on the relationship of protein concentration and absorption at 405 nm of lung lavage fluid. The maximum value of protein concentrations observed in the healthy comparison children is indicated by a dotted horizontal line. With an OD value of less than 0.038, more than 90% of the subjects with PAP had a protein concentration in their lung effluent, that was below of the healthy subjects, i.e. a protein concentration of 100 μg/ml or less. c: Bland-Altman Plot for comparison of the two methods, i.e. direct measurement of the OD of the lavage aliquot and the corresponding protein concentration, assessed by the protein assay. d: Receiver Operator Curve analysis of a cut off of of a protein concentration of 100 μg/ml. The area under the curve quantifies the overall ability of the test to discriminate those individuals with the disease, i.e. increased lavage protein concentration, and those without the disease. An area of larger than 90% (here 91%) indicates an accurate test.