The clinical role of BAL in pulmonary haemorrhages.

Several studies have shown the major value of BAL in the diagnosis of PAP [196-198]. On gross examination, the BAL fluid has a milky appearance. After gravity sedimentation a dense tan sediment can also be observed. On light microscopy, the analysis of recovered cells shows an increase in total cell count [199-1009) probably partially explained by the fact that, in these studies, the majority of patients were smokers. On cytocentrifuged slides stained by MGG, the striking feature is the finding of a variable amount of basophilic extracellular deposit mixed with enlarged foamy alveolar macrophages (AM), crystal clefts and cellular debris. This extracel-lular material as well as the cytoplasmic content of the AM show a pink PAS positive diastase resistant staining. It should be noted that this staining is weaker than that observed in transbronchial biopsy (fBB) or open lung biopsy due to the dilation induced by the BAL fluid. On electron microscopy the ultrastructural appearance is characteristic, with small lamellar bodies of wavy or regular periodicity, tubular myelin structures and myelin-like multilamellated structures with electron dense central region [101-102). Added to this extracellular material, ghost cells, AM and/or pneumocytes 11 are filled with intracellular bodies and empty vacuoles or grey lipid droplets. Different cellular profiles have been described. Some authors found an increase of lymphocytes compared to a control group with similar smoking habits [200) with an increased ratio of helper to suppressor T-cells. Others found a slight increase in neutrophils [203). Particularly in these latter cases, a careful search for pathogens has to be undertaken. In order to differentiate primary from secondary PAP, some authors have proposed an analysis of the alveolar material with specific antibodies against surfactant apoproteins. They have shown a significant difference in the quantity and repartition of the BAL 951 staining between primary and secondary forms [204). Biochemical analysis of the lavage fluid, in particular protein and lipid analysis, have been performed by many laboratories. In comparison with normal subjects, a higher protein and phospholipid concentration is always present, and qualitative abnormalities in phospholipid composition have been found [53, 205). Some authors have shown an impairment in AM function [199, 206). The value of BAL in comparison to other diagnostic procedures in PAP Few papers have compared the advantages of the different diagnostic procedures in PAP. However, in comparison with sputum analysis, transbronchial biopsy (TBB) or open lung biopsy, they have emphasized the major value …