New ultradeformable drug carriers for potential transdermal application ofinterleukin-2 and interferon-alpha: Theoretic add practical aspects

Transfersomes (TFs) are highly deformable hydrophilic lipid vesicles that a re able to penetrate the skin barrier spontaneously because of their charac teristics. Transfersomes are able to transport noninvasively low- and high- molecular-weight molecules into the body. We describe the formulation and s everal biologic characteristics of interleukin-2 (IL-2)- and interferon-alp ha (IFN alpha)-containing TFs. TFs contain natural phosphatidylcholine and sodium cholate. Recombinant human IL-2 and human hybrid IFN alpha were adde d to TFs and incubated for 24 hours at 4 degreesC. Immunotransfersomes were isolated from free IL-2 and IFN alpha by filtration (Centrisart, Sartorius ). The biologic activity of immunotransfersomes was measured by a cytotoxic lymphoid Line assay for IL-2 and by an A549-encephalomyocarditis virus ass ay for IFN; concentrations of proteins were determined by the enzyme-linked immunosorbent assay (ELISA). It was possible to incorporate a large amount of IL-2 and IFN in TFs (75-80%), and the incorporated IL-2, and IFN were b iologically active. The increased lipid/protein ratio (90.9/1.0) led to a g rowing probability of association. We were thus able to show that IL-2 and IFN are trapped by transfersomes in a biologically active form and in suffi cient concentrations for immunotherapy. In upcoming experiments these IL-2- and IFN-containing TFs will be used for a transdermal approach in the muri ne RENCA cell line model.