CELLS AND MEDIATORS IN BRONCHOALVEOLAR LAVAGE OF ASTHMATIC-PATIENTS -THE EXAMPLE OF EOSINOPHILIC INFLAMMATION

Bronchoalveolar lavage (BAL) greatly improved our understanding of ast hma allowing to demonstrate the key role of inflammation in the pathog enesis of the disease. BAL is a safe procedure, even in severe patient s when properly performed. BAL samples large and small airways and alv eoli. Cells and mediators may be measured in BALF but they only repres ent an indirect estimation of the bronchial inflammation. Before perfo rming BAL, the clinical status of the patients should be ascertained a nd drugs taken may have to be withdrawn. BALF markers should follow so me requirements: (1) markers should be released by cells that are pert inent to airways inflammation (and reparation) in asthma, and, if poss ible they should be specific of a single cell type, (2) the enumeratio n of cells or titration of the marker or of its metabolites should be specific and sensitive, (3) if possible the titration should not be mo dified by the sampling procedure, (4) pilot studies should have demons trated that the cell is increased or the secretory product is released during challenge in asthmatic subjects, (5) studies in a large number of patients should have demonstrated that the levels of the marker ar e increased in chronic asthmatics, that these levels are correlated wi th the severity of the disease and are decreased during effective anti -inflammatory treatment, and (6) if possible the cell or marker should be specific to asthma (but at present there is no such cell or marker ). Eosinophils and granule secretory products follow most of these req uirements. BAL represents an important research tool to assess the eff ects of therapeutic interventions.