Stable expression of biologically active recombinant bovine interleukin-4 in Trypanosoma brucei

We have explored the potential of Trypanosoma brucei as a eukaryotic expres sion system. Procyclic forms, which correspond to an insect-adapted stage, can easily be cultured in vitro. The cells grow to densities similar to 10- fold greater than higher eukaryotic cells and are not infectious for mammal s. An expression vector which can stably integrate into the genome was used to express high levels of recombinant bovine interleukin-4 (IL-4). Trypano some-derived IL-4 is released into the medium and is biologically active. T he recombinant protein down-regulates CD14 expression in human macrophages and inhibits NO production by stimulated bovine macrophages. (C) 2001 Feder ation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.