Traditionally, human cytokines have been expressed in non-human cells, including bacteria, yeast and mouse cells. However, the biological importance of species-specific post-translational modifications, in particular glycosylation, is increasingly being implicated as pivotal to protein function. Glycosylation is important for solubility, resistance to proteolysis, immunogenicity, biological recognition, biological activity, in vivo stability and clearance of glycoproteins including cytokines and growth factors, as up to 75% of their mass may consist of carbohydrate moieties. Clinical trials in cancer immunotherapy have attempted to benefit from the ability of autologous dendritic cells to boost antigen specific T-cell immunity. To date most clinical trials have generated dendritic cells using cytokines expressed in non-human cells. We have purified recombinant human cytokines expressed in modified human 293 cells. Human cell expressed human cytokines including IL-4, GM-CSF and TNF-alpha were used to generate dendritic cells from human peripheral blood mononuclear cells. The resulting cells exhibited a typical mature dendritic cell phenotype including expression of CD209, HLA-DR, CD40, CD80, CD83 and CD86, and were able to generate a T-cell response. In vitro comparisons of the biological activity of human cell expressed cytokines, in particular IL-4, with those expressed in other species has demonstrated that human cell expressed cytokines are more stable.
It is proposed that the enhanced biological stability of human cytokines derived from a human cell expression system would make these cytokines ideal for ex vivo derivation of immune cells such as dendritic cells for cancer therapy.
Disclosure: No relevant conflicts of interest to declare.