Modification of serum proteins in guinea pigs immunized and challenged with toluene diisocyanate

Guinea pigs were used to determine whether immunization and challenge by toluene diisocyanate (TDI) induce changes in the serum protein concentrations of the "acute-phase response" and whether TDI can form adducts with serum proteins.

Guinea pigs were immunized by weekly intradermal injections of TDI and challenged with TDI 7 days after the 3rd injection. The animals were killed 6 hours after the challenge, and serum was analyzed for protein characterization by gel electrophoresis and for specific antibodies to TDI by enzyme-linked immunosorbent assay (ELISA) and Western blotting.

The total serum protein concentration of the immunized TDI-challenged guinea pigs increased in comparison with that of nonimmunized animals [75 (SE 0.7) versus 47.4 (SE 2.3) mg/ml; ]. Albumin and alpha, and alpha2 globulins increased significantly [respectively: 65.8 (SE 0.2)%, 2.1 (SE 0.1)% and 7.2 (SE 0.1)% versus 59 (SE 1.3)%, 1.3 (SE 0.1)% and 3.7 (SE 0.1)%], whereas beta1 and beta2 globulins decreased in the immunized TDI-challenged guinea pigs [7.8 (SE 0.2)% and 0.8 (SE 0.2)% versus 15.8 (SE 0.7)% and 4.8 (SE 0.2)%]. The gamma globulin concentrations did not change significantly. In the immunized TDI-challenged animals, albumin was modified by TDI and ran faster on agarose gel electrophoresis than did albumin from nonimmunized guinea pigs. In the ELISA, only immunized animals had high titers of TDI-specific antibodies (IgG and IgG1); by blotting, the antibodies reacted against TDI, the TDI-BSA-conjugate and several TDI-conjugated guinea pig serum proteins, but they did not react against any native or denaturated serum protein when unconjugated with TDI.

These findings indicate that, in guinea pigs, immunization and challenge with TDI induces changes in serum proteins of the "acute phase response" and TDI is adducted to serum proteins with different molecular weights (eg, albumin).