Absence of IgG antibodies to TDI‐HSA in a radioimmunological study

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Abstract
Sera of ninety‐one workers with respiratory symptoms related to occupational exposure to toluene diisocyanate (TDI) were tested by a solid phase radioimmunoassay using polyvinyl plates, in an attempt to demonstrate specific IgG antibodies to a conjugate of TDI with human serum albumin (TDI‐HSA). Different conjugates were prepared. In our radioimmunoassay a TDI‐HSA 1600 (1600 μg TDI/ mg HSA), obtained at alkaline pH with borate buffer, was used; this conjugate was immunologically reactive and did not contain protein macro‐aggregates. No difference in percent of binding of radiolabelled anti‐human IgG to TDI‐HSA coated on plastic plates was found between exposed workers (asthmatic and non‐asthmatic) and fifteen normal subjects. This may suggest that either TDI‐induced bronchial asthma is not mediated by IgG antibodies, or TDI‐HSA conjugate is unsuitable to be detected by anti‐isocyanate IgG.