Diagnostic reagents in drug allergy: immunochemical specificity in the 1,2-diphenyl-pyrazolidinedione series.

Chemically defined haptenic reagents and haptenic conjugates were synthesized to be used for skin tests in allergic patients and for serological tests. One series of reagents is based on an open-chain derivative which is formed by reaction of the oxidation product of phenylbutazone, 4-hydroxyphenylbutazone, with amino functions. A second series uses the intact 1,2-diphenyl-pyrazolidine-3,5-dione molecule which is substituted in the 4-position with acetic acid. Both haptens are used in conjunction with spacer molecules which provide considerable distances between haptenic moiety and carriers. The skin test reagents are hexavalent conjugates based on the bis-penta-L-lysine carrier "PAL". Rabbit and guinea-pig antisera against the haptens were obtained by immunizations with human serum albumin conjugates. Data obtained from passive cutaneous anaphylaxis and from ELISA tests show that there is generally only slight cross-reactivity between the two series of haptenic reagents. Also, there is only modest cross-reactivity between intact drugs and haptenic reagents. No measurable crossreactions were noted between 1-phenyl-2,3-dimethyl-3-pyrazolin-5-one derivatives and haptenic reagents of the 1,2-diphenyl-pyrazolidinedione series.