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

Objectives Guinea pigs were used to determine whether immunization and chal lenge by toluene diisocyanate (TDI) induce changes in the serum protein con centrations of the "acute-phase response" and whether TDI can form adducts with serum proteins. Methods Guinea pigs were immunized by weekly intradermal injections of TDI and challenged with TDI 7 days after the 3rd injection. The animals were ki lled 6 hours after the challenge, and serum was analyzed for protein charac terization by gel electrophoresis and for specific antibodies to TDI by enz yme-linked immunosorbent assay (ELISA) and Western blotting. Results The total serum protein concentration of the immunized TDI-challeng ed guinea pigs increased in comparison with that of nonimmunized animals [7 5 (SE 0.7) versus 47.4 (SE 2.3) mg/ml; ]. Albumin and alpha, and alpha, glo bulins increased significantly [respectively: 65.8 (SE 0.2)%, 2.1 (SE 0.1)% and 7.2 (SE 0.1)% versus 59 ISE 1.3)%, 1.3 (SE 0.1)% and 3.7 (SE 0.1)%], w hereas beta, and beta, 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 r an faster on agarose gel electrophoresis than did albumin from nonimmunized guinea pigs. In the ELISA, only immunized animals had high titers of TDI-s pecific antibodies (IgG and IgG(1)); by blotting, the antibodies reacted ag ainst TDI, the TDI-BSA-conjugate and several TDI-conjugated guinea pig seru m proteins, but they did not react against any native or denaturated serum protein when unconjugated with TDI. Conclusions These findings indicate that, in guinea pigs, immunization and challenge with TD induces changes in serum proteins of the "acute phase res ponse" and TDI is adducted to serum proteins with different molecular weigh ts (eg, albumin).