The conjugation of an AQP1-directed immunotoxin in the study of site-directed therapy within the CNS

Surash Surash, Peter Nemeth, Aruna Chakrabarty, Paul Chumas

Research output: Contribution to journalArticle

3 Citations (Scopus)


Purpose: The water channel, aquaporin (AQP)1, is highly specific to the choroid plexus (CP) epithelium within the brain. It is therefore a potential target through which therapeutic agents could be selectively directed to the CP. Here we describe the conjugation of a monoclonal antibody (mAb), raised against an extra-cellular domain of AQP1, to the A chain of ricin (RCA). This reagent should allow study of a highly specific chemical lesion of the CP. Methods: A published method was used to couple the anti-AQP1 mAb to the A chain of ricin using an SPDP cross-linker. The conjugate was purified by Superdex S-200 chromatography. Column fractions were analysed by SDS-PAGE and Western blotting. Fractions containing conjugate were assayed for cytotoxicity on rat CP cells in culture, using a WST-1 viability assay to assess cell death. Results: SDS-PAGE and Western blotting demonstrated separation of conjugated anti-AQP1 mAb from unconjugated ricin by the Superdex column. Cultured rat CP cells were killed with an IC50 of 1.81 μg/ml when exposed to the anti-AQP1 mAb-RCA conjugation reaction products. Selectivity of this reagent was demonstrated by the higher IC50 exhibited by non-AQP1-expressing primary fibroblast cultures and cultures exposed to the reaction products from the non-specific IgG-RCA conjugation attempt. Conclusion: We have been able to demonstrate selective cytotoxicity in vitro of an anti-AQP1 mAb-RCA conjugate. We hope that this work will generate further interest in the use of this site-specific conjugate to target the CP in conditions such as hydrocephalus, tumours that arise from here, and other AQP1-expressing tumours.

Original languageEnglish
Pages (from-to)811-818
Number of pages8
JournalChild's Nervous System
Issue number5
Publication statusPublished - May 1 2011



  • Aquaporin
  • Choroid plexus
  • Hydrocephalus
  • Immunotoxin

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Clinical Neurology

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