On the immunochemical specificity of pyrazolinone and pyrazolidinedione reactions

Haptenic groups based on the 1-phenyl-2,3-dimethyl-3-pyrazolin-5-one and 1,2-diphenyl-pyrazolidine-3,5-dione structures conjugated to human serum albumin gave antibody responses in rabbits which were compared with those raised against the same haptens conjugated via spacer bridges to the protein carrier. The spacing up to 12.4 A had no marked influence on the antibody specificity evaluated by haptenic inhibition of ELISA. The specificities are more pronounced than those found with e.g. anti-penicilloyl antibodies which seems in line with clinical experience involving e.g. phenylbutazone, sulfinpyrazone, propyphenazone and metamizole. It is argued that such strict specificities may lead to false negative tests in diagnostic procedures in vitro as well as in skin testing.