Analysis of immunoradiological properties of radiolabelled monoclonal antibody for tumour localization.
This investigation demonstrates the effect of 131I incorporation on antibody function and radionuclide delivery to target antigens by radiolabelled antibody. For our antihepatoma monoclonal antibody with affinity constant K = 1.12 x 10(8) M-1 and maximum binding capacity of 1.66 x 10(6) sites on each hepatoma cell, a linear decrease in K was observed with the increase in specific activity from 1.90 to 97.12 microCi microgram-1. Radioiodination also inactivated nearly half of the immunoreactive molecules. Most interestingly, when magnitudes of antibody mass and radioactivity which bound target cells were compared for preparations of different specific activities, each contained similar nanomolar of antibody molecules. We recognized the slight gain in nanogram bound opposing to the great loss in bound counts per minute (cpm) as consequences of decreasing levels of 131I incorporation from 97.12 and 26.64 to 1.90 microCi microgram-1. Our findings suggest that the quality of radiolabelled antibody should be assessed in both its immunological function and radioactive transfer capability.
Boonkitticharoen
V
V
Department of Radiology, Faculty of Medicine, Ramathibodi Hospital, Bangkok, Thailand.
Laohathai
K
K
D000911:Antibodies, Monoclonal; D006801:Humans; D007457:Iodine Radioisotopes; D007553:Isotope Labeling; D009369:Neoplasms / Q000000981:diagnostic imaging*; D016719:Radioimmunodetection
D000911:Antibodies, Monoclonal; D007457:Iodine Radioisotopes