A POTENTIAL USE OF A MONOCLONAL-ANTIBODY TO PLACENTAL ALKALINE-PHOSPHATASE (PLAP) TO DETECT LYMPH-NODE METASTASES OF SEMINOMA

Purpose: To evaluate the ability of monoclonal antibodies against alka line phosphatase (AL-P) for tumor immunolocalization in nude mice. Mat erials and Methods: Two monoclonal antibodies against placental alkali ne phosphatase (FLAP) and liver alkaline phosphatase (LAP) were intrav enously administered to nude mice bearing AL-P producing HeLa Hep 2 tu mors. Sera and tumors from 65 patients with testicular germ cell tumor s were examined for PLAP levels. Results: Levels of FLAP or LAP in the HeLa xenografts were shown to be comparable to levels of FLAP in semi nomas, including lymph node metastases, or nonseminomas, respectively. A biodistribution study showed that the percentage of the injected do se of I-125 labelled anti-FLAP in the xenografts was rather constant a t around 7% until 7 days after injection, while the percentage of the injected dose of I-125 labelled anti-LAP MAb decreased with time as in other tissues which do not contain significant amounts of FLAP or LAP . On scintiscan, the xenografts in nude mice were distinctly visualize d at 7 days after injection of anti-FLAP MAb. Conclusions: These data may support the potential use of the anti-FLAP MAb for the immunodetec tion of lymph node metastases of seminoma.