Nitrocellulose-based RAST to detect IgE antibodies in workers hypersensitive to diphenylmethane-4,4'-diisocyanate

RAST was performed using both nitrocellulose (NC) and paper discs to compare these solid supports for ability to detect IgE antibodies in sera from two patients with hypersensitivity to the industrial chemical, diphenylmethane-4,4'-diisocyanate (MDI). NC disc had distinct advantages in ease of coupling the hapten-conjugate antigen to discs, and in use of lesser amounts of antigen. With regard to sensitivity, NC discs were better able to distinguish the positive sera from 34 control sera including those with elevated levels of total IgE. In both RAST systems, inhibition studies indicated high specificity of antibodies for MDI, with no reactivity detected toward the serum albumin portion of the MDI-HSA conjugate antigen. However, only in the NC RAST did antibodies from both patients react with p-tolyl isocyanate inhibitor. Based on the above results, NC discs displayed several advantages in RAST and are recommended for routine serological assay of isocyanate-specific antibodies.