Structure and expression of cDNA and genes for human interferon‐beta‐2, a distinct species inducible by growth‐stimulatory cytokines

Induced human fibroblasts produce several mRNAs encoding interferon (IFN) activity. We previously cloned cDNA for a 1.3‐kb RNA designated IFN‐beta 2 and distinct from the 0.9‐kb IFN‐beta 1 mRNA. In vitro transcription‐‐translation mapping of the full‐length IFN‐beta 2 cDNA sequence, shows that it encodes a 23.7‐kd protein of 212 amino acids. This cDNA, fused to the SV40 early gene promoter, was transfected and amplified in Chinese hamster ovary cells and clones were obtained which constitutively produce human interferon activity. Two IFN‐beta 2 genomic clones were isolated and their expression in hamster and mouse cells also produces biologically active rIFN‐beta 2. Specific immunoassays show that IFN‐beta 2 secreted by DNA‐transformed rodent cells is a processed 21‐kd protein, whose activity is cross‐neutralized by antibodies to human IFN‐beta 1 but not to IFN‐alpha or gamma. The immunoassay also demonstrates the induction of IFN‐beta 2 secretion by fibroblasts in response to growth‐regulatory cytokines, such as interleukin‐1 and tumor necrosis factor. The function of this IFN‐beta 2 as an autoregulatory inhibitor of cell growth is discussed.