Expression of interleukins in L cells transfected with human DNA

We have obtained, by transfection of mouse L cells with total human DNA, clones that constitutively secreted human interleukins IL1, IL2 and B-cell grown-factor activities, as assessed by specific biological assays. Southern analysis with IL2 and IL1 beta cDNAs confirmed the integration of the corresponding human genes in the genome of recipient mouse cells and showed their amplification and rearrangement. All the four IL2-secreting clones integrated in the mouse genome the human IL2 gene. Three out of the sixteen IL1-producing clones contained the IL1 beta gene. The IL1 activity secreted by the remaining clones exhibited a molecular mass of 17 kDa similar to that reported for mature human macrophage IL1. Our results demonstrate that DNA-mediated gene transfer may represent a suitable tool for the production of human growth and differentiation factors and the cloning of their genes.