Title

Pretargeting vs. direct targeting of human betalox5 islet cells subcutaneously implanted in mice using an anti-human islet cell antibody.

Document Type

Article

Publication Date

7-2012

JAX Source

Nucl Med Biol 2012 Jul; 39(5):645-51.

PMID

22316614

Abstract

INTRODUCTION: We previously demonstrated MORF/cMORF pretargeting of human islets and betalox 5 cells (a human beta cell line) transplanted subcutaneously in mice with the anti-human islet antibody, HPi1. We now compare pretargeting with direct targeting in the beta cell transplant model to evaluate the degree to which target/non-target (T/NT) ratios may be improved by pretargeting.

METHODS: Specific binding of an anti-human islet antibody HPi1 to the beta cells transplanted subcutaneously in mice was examined against a negative control antibody. We then compared pretargeting by MORF-HPi1 plus (111)In-labeled cMORF to direct targeting by (111)In-labeled HPi1.

RESULTS: HPi1 binding to betalox5 human cells in the transplant was shown by immunofluorescence. Normal organ (111)In backgrounds by pretargeting were always lower, although target accumulations were similar. More importantly, the transplant to pancreas and liver ratios was, respectively, 26 and 10 by pretargeting as compared to 9 and 0.6 by direct targeting.

CONCLUSIONS: Pretargeting greatly improves the T/NT ratios, and based on the estimated endocrine to exocrine ratio within a pancreas, pretargeting may be approaching the sensitivity required for successful imaging of human islets within this organ.