Cyclosporin partitions into phospholipid vesicles and disrupts membrane architecture

Mark Haynes*, Laphalle Fuller, Duncan H. Haynes, Joshua Miller

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Cyclosporin is a fungal metabolite demonstrating potent immunosuppressive activity both in vitro and in vivo, but the mechanism of action is poorly understood. Using [3H]dihydrocyclosporin C ([3H]CsC) we observed significant binding by mononuclear cells, erythrocytes and phosphatidyl choline (PC) vesicles which was reversible by the addition of excess CsA. Trypsin, pronase or heat treatments demonstrated that B cells and adherent cells express a protease-sensitive membrane binding site not observed on T cells. The nature of the interaction between CsA and the PC vesicles was studied using the membrane surface probe 1-anilino-8-naphthyl sulfonic acid (ANS-). ANS--induced fluorescence was reduced by 24% in the presence of 4.75×10-7 M CsA indicating that CsA displaces ANS- from the PC vesicles. CsA also effected a shift in the phase transition temperature of PC vesicles from 23°C to 19°C. Finally, the rate of concanavalin A (Con A)-induced cap formation by T lymphocytes was approximately doubled in the presence of 2.6×10-5 M CsA. These data demonstrate that CsA partitions into phospholipid vesicle membranes and the plasmalemma of mononuclear cells resulting in an increased membrane fluidity.

Original languageEnglish (US)
Pages (from-to)343-349
Number of pages7
JournalImmunology Letters
Issue number5-6
StatePublished - 1985


  • cyclosporin
  • hydrophobic interactions
  • lipid vesicles

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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