Monoclonal Antibodies as Drugs or Devices: Practicaland Regulatory Aspects

Specific, high affinity colchicine binding monoclonal antibodies: development and characterization of the antibodies

Nine colchicine specific monoclonal antibodies have been developed by immunizing BALB/c mice with a colchicine-keyhole limpet hemocyanin (Col-KLH) conjugate prepared using a bishydroxysuccinimide coupling reagent. Of four immunization procedures examined, intraperitoneal injection of the antigen attached to acid treated E. coli resulted in the maximum antigen specific antibody titers. A colchicine bovine serum albumin (Col-BSA) conjugate, prepared using a water soluble carbodiimide coupling technique, formed the basis of an enzyme linked immunosorbent assay used for screening hybridomas for colchicine specific antibody secretion and for determining the relative affinity and specificity profile of the monoclonal antibodies. All antibodies demonstrated high affinity, saturable binding to colchicine and low cross-reactivity with a panel of compounds structurally related to colchicine. The IC50 for the highest affinity antibody, C44, was 3.6 +/- 0.84 nM colchicine in the competitive enzyme immunoassay. The affinity of this antibody determined from Scatchard analysis of antibody binding to tritiated colchicine was 0.66 +/- 0.11 nM. Antibody C44 has the level of specificity and affinity suitable for a sensitive and selective immunoassay of colchicine for monitoring therapeutic drug levels. In addition, this antibody provides a specific pharmacologic antagonist for studies of colchicine's therapeutic mechanism and has the potential to reverse colchicine toxicity.