DEVELOPMENT OF RADIOIMMUNOASSAYS ON MICROPLATE - APPLICATION FOR CA-GL AND CA-BR TUMOR-MARKERS

By taking advantage of a newly available microplate counter for radioa ctivity and the organic solvent-resistant, pigmented microplates, we h ave successfully established radioimmunoassays (RIA) for both CA-GI an d CA-BR on microplate for routine clinical use. In the process of assa y development, we found that both pigmented PicoPlate, made of acrylon itrile, and polystyrene Microlite 2 can be coated with antialpha fetop rotein (AFP) and antinerve growth factor (NGF) and used for setting up immunoassays for AFP and nerve growth factors. There were no problems following a test format of either competitive binding or sandwich des ign. Microlites 2 is recommended over PicoPlate because Microlites 2 i s made of polystyrene, which is less expensive and separable into 8-we ll strips or even single wells. Single-well separation allows for the use of regular gamma counters in case Topcount is unavailable. We also found that the sensitivity of these tests was not significantly affec ted even though Topcount counts the weaker beta emissions. Similar dos e-response curves could also be generated between original Biomira tub e assays and assays using PicoPlate or Microlite 2 coated with protein antigens CA-Br and CA-GI. Excellent correlations were also obtained b etween the microplate assays and the Biomira tube assays for CA-GI and CA-Br using groups of serum specimens from cancer patients. We recomm end the development of various RIAs on the microplate: it requires les s reagents and less sample handling by the technologists and it can be essentially automated. (C) 1993 Wiley-Liss. Inc.