Transcutaneous IL-2 uptake mediated by Transfersomes depends on concentration and fractionated application

Transfersomes (TF) are new, ultradeformable carriers with characteristics that enable them to penetrate the skin spontaneously. TFs are able to transport noninvasively both low- and high-molecular-weight molecules into the body.

TFs contain phosphatidylcholine and sodium cholate. Recombinant human interleukin-2 (Proleukin, Chiron) was added to the TFs and incubated for 24 h at 4 degrees C. The immunotransfersomes (ITF) were isolated from free interleukin-2 (IL-2) by filtration (Centrisart, Sartorius). Twenty-five thousand, 50,000 and 150,000 IU pure IL-2 and ITFs, which had been incubated with the same concentrations of IL-2, were applied subcutaneously (s.c.) (n = 8) and epicutaneously (e.c.) (n = 8) to mice. The IL-2 serum concentrations in the mice were then measured by ELISA after 2, 4, 6, 8, 10 and 24 h. Fractionation of the transdermal IL-2 application was also examined as a means of improving uptake.

In concentrations of 25,000 and 50,000 IU IL-2, the subcutaneous application of ITFs resulted in a longer lasting IL-2 serum concentration than did the subcutaneous application of pure IL-2. While at 25,000 IU, the epicutaneous application of ITFs resulted in serum concentrations comparable to those resulting from s.c. application, at 50,000 and 150,000 IU, only 50% and 22.6% of the maximum serum concentration resulting from the s.c. application of pure IL-2 was obtained. Fractionating the transdermal IL-2 application improved uptake.

We were able to show that biologically active IL-2 can be bonded to TFs up to 75%. It is possible to transport IL-2 through the skin using TFs. Both the concentration-dependent saturation of the TFs with IL-2 and fractionation of the application resulted in differing degrees of transcutaneous IL-2 uptake.