Site-Specific PEGylation of Interleukin-2 Enhances Immunosuppression via the Sustained Activation of Regulatory T Cells

The authors showed that the pharmacokinetics and half-life of IL-2 could be substantially improved by orthogonally conjugating the cytokine to poly(ethylene glycol) (PEG) moieties via a copper-free click reaction through the incorporation of azide-bearing amino acids at defined sites.