Monoclonal antibodies against a sulfathiazole derivative for the immunochemical detection of sulfonamides

To prepare monoclonal antibodies (mAbs) against the generic part of sulfona mides, a sulfathiazole derivative was chemically linked to carrier proteins in such a way that the aromatic amino group, common to all sulfonamides, w as distal to the proteins. Four mice were immunized with the sulfathiazole- protein derivatives. The spleen cells of one of the mice were fused with my eloma cells to produce hybridomas of which the supernatants were screened i n an indirect ELISA (iELISA) for the presence of sulfathiazole antibodies. After cloning, positive supernatants were tested in a competitive iELISA (c iELISA) for inhibition with 18 sulfonamides. This resulted in four differen t mAbs (all IgG1 kappa light chain) which recognized several sulfonamides. By use of the best monoclonal (27G3) and an optimized ciELISA protocol, eig ht structurally different sulfonamides showed 50% inhibition at concentrati ons less than 100 ng ml(-1) or 5 ng/well. However, other relevant sulfonami des (such as sulfadimidine, sulfatroxazole and sulfachloropyrazine) were de tected at a high level only with this mAb. This means that the ciELISA (wit h the best Mab) showed a broad specificity for sulfonamides but the sensiti vity towards the different sulfonamides varied too much to call it a generi c sulfonamide ELISA.