Bronchoalveolar lavage has been widely used to sample the lower respiratory tract. Most of the material recovered with this technique represents alveolar contents. A number of modifications have been suggested in order to obtain samples relatively enriched for bronchial material. In order to be able to use a standard technique for bronchoalveolar lavage to sample both airways and "routine" alveolar material, a simple modification of the technique as described by Reynolds and Newball was used: five sequential 20-ml aliquots were infused into the lower respiratory tract, and each aliquot was immediately aspirated. The return from the first aliquot was processed separately from the return from the subsequent four aliquots. These last four aliquots were pooled. Analysis of the first aliquot revealed it to be enriched for ciliated epithelial cells when compared with the subsequent aliquots. There were also differences in inflammatory cell composition with the bronchial sample containing relatively more neutrophils and relatively less lymphocytes. Aspiration during transoral bronchoscopy was documented by quantifying salivary amylase in the bronchial and alveolar lavage fluids. It was estimated, however, that the aspiration was not of quantitative significance in the vast majority of subjects studied. Finally, with the technique of fractional processing of bronchoalveolar lavage samples, it was possible to compare the protein concentrations in bronchial and alveolar lavages. Most prominent among the differences was a marked relative enrichment in the bronchial samples for immunoglobulin A. The technique of fractional processing of bronchoalveolar lavage samples provides a simple means to obtain samples enriched for bronchial and alveolar components. This should facilitate analysis of lower respiratory tract specimens in airway disease.

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The nature of the procoagulant activity of normal bronchoalveolar fluid was examined both qualitatively and quantitatively. Unconcentrated, cell-free lavage freshly obtained from normal volunteers clotted normal plasma in a mean of 84 +/- 20 s. The procoagulant activity was initiated by Factor VII-tissue factor complexes as judged by differential activity in various plasmas genetically deficient in single clotting factors, by neutralization of the procoagulant activity with antibodies to either Factor VII or tissue factor, and by a Factor X activation assay. Preincubation of the lavage with calcium was required to demonstrate Factor VII activity in unconcentrated samples. The cell-free fluid contained about 8,500 thromboplastin units/mg protein, equivalent to a third of the thromboplastin standard and indicating high amounts of cofactor. Quantitation of Factor VII was estimated by functional analysis in coagulation and amidolytic assays with reference to dilutions of normal plasma of known Factor VII concentration. When lavage and diluted plasma were adjusted to yield equivalent amidolytic activities, the average ratio of the Factor VII-clotting activity of the alveolar fluid relative to plasma Factor VII was 19 +/- 7, suggesting the presence of Factor VIIa in lavage. In contrast to previous reports with serum or activated plasma, immunoblots of concentrated lavage revealed only single-chain Factor VII, and 125I-Factor VII added to the fluid was not converted to 125I-Factor VIIa, suggesting a unique control mechanism in the lung compartment which differs from plasma. When equivalent Factor VII amidolytic activities in diluted plasma and cell-free lavage were compared, the rates of Factor Xa formation were very similar.(ABSTRACT TRUNCATED AT 250 WORDS)

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