Reaginic antibody in the lung lining fluid: Analysis of normal human bronchoalveolar lavage fluid IgE and comparison to immunoglobulins G and A

BAL has been used to recover the lung lining fluid from 43 normal volunteers. We have measured albumin and immunoglobulins G, A, and E in sera and concentrated lavage fluids obtained from these subjects and constructed ratios of immunoglobulin/albumin in serum and lavage in order to assess the relative contributions of serum transudation and of local synthesis to the presence of immunoglobulin in the airways. This analysis revealed that most IgA was locally synthesized in both smokers and nonsmokers. In all nonsmokers and 80% of smokers, the IgG/albumin ratio was equivalent to the same ratio in serum, reflecting passive transudation of immunoglobulin G from serum. However, 20% of smokers had lavage IgG/albumin ratios 〉2 S.D. above the mean for simultaneously obtained serum specimens, suggesting a significant contribution of local synthesis. By contrast, the mean serum IgE/albumin ratio significantly exceeded the mean lavage IgE/albumin ratio. Moreover the concentration of IgE in the lavage fluid correlated directly with the serum IgE concentration and with the presence of basophils in the lavage cell population, suggesting that the IgE detectable in the lung lining fluid came from serum transudation or was eluted from cells binding IgE in the airways.