Identification of IL-6 and its pleiotropic functions

Identification of IL-6 and its pleiotropic functions IL-6 was originally identified as an antigen-nonspecific Bcell differentiation factor in the culture supernatants of mitogenor antigen-stimulated peripheral blood mononuclear cells that induced B cells to produce immunoglobulins [1,2], and was named B-cell stimulatory factor 2 (BSF-2). The cDNA encoding human BSF-2 was cloned in 1986 [3]. Simultaneously, IFN-β2 [4,5] and a 26-kDa protein [6] in fibroblasts were independently cloned by different groups and found to be identical to BSF-2. Later, a hybridoma/plasmacytoma growth factor [7–10] and a hepatocyte-stimulating factor [11–13] were also proven to be the same molecule as BSF-2. Although various names have been used for this molecule because of its multiple biological activities, it is now known as IL-6.