New perspectives on the design of cytokines and growth factors.

A combination of molecular modelling, conventional epitope scanning and combinatorial techniques, such as phage display and DNA shuffling, has greatly improved our understanding of ligand-receptor interactions. It has therefore been possible to develop powerful cytokine-growth factor antagonists and new designer cytokines, with altered receptor specificities or with greatly enhanced biological activity. Recently, small circular peptides that mimic or block the effects of natural cytokines and growth factors have been developed; such small peptides are likely to open new avenues in therapeutics.