Recombinant IL-2 (without PEG modification) was administered to HIV-infected patients by daily intradermal injection. At the low doses used, this was non-toxic, well-tolerated, and gave a systemic response as measured by natural killer cell and lymphokine-activated killer cell activity, but required daily administration. In the current study, the PEG modification of IL-2 is used since it has a much longer prolonged half-life compared with the non-PEG compound, without loss of functional activity.