Normalization of Lavage Type 3 Procollagen Peptide Levels
No satisfactory reference component for normalization of lavage fluid proteins is currently available. Increased leakage of proteins from the capillaries to the alveoli is known to occur in sarcoidosis and this leakage can vary with disease stage and severity. In a situation of capillary-alveolar leakage, type 3 procollagen peptide (MW, 45,000) can pass from plasma to the alveoli. To ensure that the observed patient-to-patient variation in lavage type 3 procollagen peptide levels was not simply due to variation in capillary-alveolar leakage, type 3 procollagen peptide levels were normalized to lavage protein content. It is acknowledged that this method of normalization does not account for increased protein production within the lung, and thus, may lead to an underestimation of the local production of type 3 procollagen peptide in the lung. However, normalization to protein content ensures that the observed variations in lavage type 3 procollagen peptide levels reflect specific changes in type 3 collagen metabolism in the lung, rather than alterations in general protein metabolism. cfm-online-shop.com
Measurements of FVC, FEV,, and carbon monoxide single breath diffusion capacity (transfer factor, Dsb) were performed using a vitalograph spirometer and a PK Morgan transfer test model D. The percent predicted values for FVC, FEV,, and Dsb were calculated as described by Cotes et al, corrected for use with the Morgan transfer test instrument. Results were expressed as the percentage of predicted normal. Chest roentgenograms were graded according to the Siltzbach classification system. Sarcoidosis patients were followed for a minimum of 12 months following initial lavage and pulmonary function tests repeated.
Lavage fluid data are expressed as medians and absolute ranges. Nonparametric tests (the Wilcoxon rank sum test, Spearmans rank correlation test and the Kruskal-Wallis one way analysis of variance) were used for statistical analysis of fluid data. Pulmonary function data are expressed as means with standard deviations.