Radioimmunodetection of neuroblastoma cells with I-131-radiolabelled antibodies

The murine anti-neuroblastoma monoclonal antibodies 15/7 and 19/1/4 should be tested for specific radiolocalization of neuroblastoma by immunoscintigraphic imaging of this tumour growing in mice. Radioiodination of both antibodies was done by chloramine-T method resulted in an immunoreactivity of 75%. The calculated specific activity varied from 51.1 to 126.2 kBq/microgram IgG. In each case, about 500 kBq of labeled antibodies were intraperitoneally injected into human neuroblastoma (SK-N-MC, SK-PN-DW and IMR 5) xenografted severe complete immunodeficient (SCID) mice. Whole-body scintigraphy was performed daily by a scintiscanner to localize the tumour site. After last scanning principal organs were removed and their I-131-uptake was determined by measuring the impulse rate. The best scintigrams were done with I-131-19/1/4 at the second day after antibody injection. Radioconjugates were accumulated at highest in the tumour at the third day after application of 15/7 and 19/1/4 with a tumour uptake of 0.4 and 2.2 per cent of injected dose per gram (%ID/g), respectively. The 15/7-moAbs was accumulated approximately 9-fold higher in the SK-N-MC and SK-PN-DW grafts than in principal organs, whereas the tumour/non-tumour-ratio of the 19/1/4 moAb was 3:1. The results indicate the efficacy of these two neuroblastoma antibodies in radiolabelling and their usefulness for tumour imaging of neuroblastoma engrafted SCID-mice.