TOLUENE DIISOCYANATE PROTEIN ADDUCTS IN THE BRONCHOALVEOLAR LAVAGE OF GUINEA-PIGS EXPOSED TO VAPORS OF THE CHEMICAL

To investigate the process of toluene diisocyanate (TDI) sensitization, studies were conducted to identify TDI-protein adducts in the bronchoalveolar lavage (BAL) fluid of guinea pigs exposed to a sensitizing atmosphere of the commercially used 4:1 mixture of 2,4- and 2,6-TDI. Animals were exposed to 2 ppm TDI for 3h. Immediately thereafter lungs were lavaged. TDI-modified proteins in the lavage fluid were identified by immunologic staining with a highly sensitive and specific rabbit antiserum raised to a TDI-keyhole limpet hemocyanin (TDI-KLH) conjugate. The sensitivity Of the antiserum was demonstrated by its ability to identify TDI-guinea pig serum albumin (GSA) adducts with as few as 0.7 mol of TDI/mol of protein. The antiserum did not react with GSA not with a GSA adducted with another aromatic diisocyanate, diphenyl-methane 4,4'-diisocyanate, TDI-protein adducts in the BAL fluid were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblotting with use of the rabbit anti TDI-KLH antiserum. At least 5 protein bands were recognized by the antiserum. Electrophoretic mobilities indicated molecular sizes equivalent eo 10.5, 38, 45, 66, and 148 kDa. Employing a murine anti-GSA antibody in immunoaffinity chromatography, one of the proteins in the 66-kDa band was identified as serum albumin. Attempts to purify the TDI-albumin adduct using a Cibacron-Sepharose column were unsuccessful. Studies with a model TDI0.7-GSA conjugate (which contained an average of 0.7 mol of TDI/mol of GSA) indicated that the TDI-albumin was not retained by the triazine dye column unless the adducted protein was first reduced by incubation with mercaptoethanol. These studies indicate that immunologic procedures can be used to identify covalently bound TDI-proteins in bronchoalveolar washings following in vivo exposure of guinea pigs to atmospheres of TDI.