Enzyme immunoassay of neocarzinostatin using beta-galactosidase as label.

A novel convenient procedure was introduced for enzyme labelling of neocarzinostatin (NCS) with beta-D-galactosidase using a new hetero-bifunctional reagent N-(gamma-maleimidobutyryloxy) succinimide (GMBS). With the enzyme labelled NCS and a rabbit anti-NCS serum which was elicited in a rabbit immunized with NCS in complete Freund's adjuvant, a highly sensitive enzyme immunoassay which can quantify a femto mol order NCS was developed. Accuracy and precision of the assay as well as a comparison with the immunodiffussion method were studied with satisfactory results. This enzyme immunoassay of NCS was applicable to monitoring serum NCS levels of patients in clinical treatment of the antitumor agent.