IGA, IGG AND IGM QUANTIFICATION IN BRONCHOALVEOLAR LAVAGE FLUIDS FROMALLERGIC RHINITICS, ALLERGIC ASTHMATICS, AND NORMAL SUBJECTS BY MONOCLONAL ANTIBODY-BASED IMMUNOENZYMETRIC ASSAYS

Recent reports have suggested that human secretory IgA (sIgA) may have a role in the mediation of atopic disease. We have studied the levels of sIgA, IgA, IgG and IgM in bronchoalveolar lavage (BAL) fluids coll ected from lungs of healthy non-allergic adults (n = 14), allergic sub jects with rhinitis (n = 15), and allergic asthmatics (n = 13), using a panel of monoclonal antibody-based immunoenzymetric assays (IEMAs). In contrast to commercially available immunodiffusion and nephelometri c assays, these IEMAs employ highly specific monoclonal antibodies and demonstrate required precision (intra-assay CVs < 17%), parallelism ( inter-dilutional CVs < 20%) at minimal detectable immunoglobulin level s in the ng/ml range, and excellent specificity with < 0.1% crossreact ivity for heterologous immunoglobulin isotypes. Using these assays, we have observed a significant correlation between sIgA levels and total IgA levels in BAL fluids from all the study patients (r = 0.94; p < 0 .01). The percentage of sIgA to total IgA was 84.0 +/- 2.2%. sIgA in B AC fluids from allergic rhinitics (18.0 +/- 2.5 mu g/ml) and allergic asthmatics (15.5 +/- 2.5 mu g/ml) were higher than those from nonaller gic subjects (10.2 +/- 1.9 mu g/ml). The only statistically significan t difference in sIgA levels was observed in BAL fluids from the rhinit ics and nonallergic groups (p = 0.03). Similar differences among the g roups were found for levels of total IgA in BAL fluid. There were no s ignificant differences in the levels of IgM and IgG in BAL fluids amon g the three groups of subjects. We conclude from these results that Ig A is the predominant immunoglobulin on the airway surface and that it appears to be produced locally.