Indirect assessment of 4,4'-diphenylmethane diisocyanate (MDI) exposure by evaluation of specific humoral immune responses to MDI conjugated to human serum albumin.
BACKGROUND
A study of occupational asthma among workers exposed to 4,4'-Diphenylmethane Diisocyanate (MDI).


OBJECTIVE
To demonstrate if serum concentrations of MDI-specific IgG or IgE are sensitive biological markers of disease or of MDI exposure.


METHODS
The study group consisted of nine MDI-exposed workers and nine nonexposed workers. Air sampling for MDI and polymethylene polyphenyl isocyanate, occupational and medical histories, respiratory physical exams, pre- and postshift spirometry, and self-administered peak expiratory flow rates were performed. Serum specific IgE and IgG antibodies to an MDI-human serum albumin (HSA) conjugate were assayed by the radioallergosorbent test and the enzyme-linked immunosorbent assay, respectively, and compared to nine nonexposed laboratory controls.


RESULTS
No definitive cases of occupational asthma were documented. The mean level of MDI-specific IgG was significantly greater among exposed workers compared to nonexposed workers and laboratory controls (p = 0.04). Mean levels of TDI and HDI-specific IgG were also increased.


CONCLUSIONS
This study demonstrates that serum concentrations of MDI-specific IgG appear to be a moderately sensitive biological marker of MDI exposure, but not an indicator of occupational asthma. Workers with IgG antibodies specific for one diisocyanate-HSA conjugate exhibit cross-reactivity to antigens prepared with other diisocyanates.
Lushniak
B D
BD
Hazard Evaluations and Technical Assistance Branch, National Institute for Occupational Safety and Health, Cincinnati, OH, USA.
Reh
C M
CM
Bernstein
D I
DI
Gallagher
J S
JS
D000328:Adult; D000485:Allergens; D000917:Antibody Formation; D015415:Biomarkers; D003429:Cross Reactions; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007073:Immunoglobulin E; D007074:Immunoglobulin G; D017953:Isocyanates; D008297:Male; D016273:Occupational Exposure; D011852:Radioallergosorbent Test; D001559:Benzhydryl Compounds
D000485:Allergens; D015415:Biomarkers; D007073:Immunoglobulin E; D007074:Immunoglobulin G; D017953:Isocyanates; C005969:4,4'-diphenylmethane diisocyanate; D001559:Benzhydryl Compounds