Methodology for assaying recombinant interleukin-2 associated with liposomes by combined gel exclusion chromatography and fluorescence

A simple methodology based on fluorescence and gel exclusion chromatography (GEC) has been developed to assay recombinant Interleukin-2 (rIL-2) associated with vesicles. A Sephadex G75 column was used to separate the liposomes from non-entrapped rIL-2. The elution of the rIL-2 liposomes was monitored by coupling fluorescent and light scattering detection. The solubilisation of the vesicles with octylglucoside (OG) before the assay was necessary to avoid interference from light scattering. This methodology can be automated to yield an on-line system that can separate, solubilise and quantify rIL-2 in liposome samples. It can be extended to any protein associated with vesicles provided that the former can be detected by fluorescence.