Presence of specific IgG antibodies in blood sera of 23 subjects suffering from isocyanate alveolitis. Note that all but five subjects show significant levels of such antibodies. The diisocyanates toluylene disocyanate (TDI), methylene diphenyl diisocyanate (MDI) and hexamethylene diisocyanate (HDI) bound to human serum albumin (HSA) were used for immune absorbent assay (CAP immunoanalysis) as described. For methodological details see Baur , Budnik et al. . Specific IgG antibodies in blood sera from a patient suffering from humidifier lung due to exposure to contaminated humidifier water (Figure 1C). Shown is ELISA assay with anti IgG antibodies recognising dose specific reaction to various concentrations of workplace related humidifier water antigens. The negative and positive controls show lab intern positive and negative samples from patients with strong signal (positive reaction) and pool serum from healthy subjects without contact with humidifier aerosols (negative control, unspecific binding).