BIOLOGICAL-ACTIVITY AND METABOLIC-CLEARANCE OF RECOMBINANT HUMAN FOLLICLE-STIMULATING-HORMONE PRODUCED IN SP2 0 MYELOMA CELLS/

Human follicle stimulating hormone is a pituitary glycoprotein that is essential for the maintenance of ovarian follicle development and tes ticular spermatogenesis. Like other members of the glycoprotein hormon e family, it contains a common a subunit and a hormone specific beta s ubunit. Each subunit contains two glycosylation sites. The specific st ructures of the oligosaccharides of human follicle stimulating hormone have been shown to influence both the in vitro and in vivo bioactivit y. Since the carbohydrate structure of a protein reflects the glycosyl ation apparatus of the host cells in which the protein is expressed, w e examined the isoform profiles, in vitro bioactivity and metabolic cl earance of a preparation of purified recombinant human follicle stimul ating hormone derived from a stable, transfected Sp2/0 myeloma cell li ne, and pituitary human follicle stimulating hormone. Isoelectric focu ssing and chromatofocussing studies of human follicle stimulating horm one preparations both showed a more basic isoform profile for the reco mbinant human follicle stimulating hormone compared to that of pituita ry human follicle stimulating hormone. The recombinant human follicle stimulating hormone had a significantly higher radioreceptor activity compared to that of pituitary human follicle stimulating hormone, cons istent with a greater in vitro potency. Pharmacokinetic studies in rat s indicated a similar terminal half life (124 min) to that of the pitu itary human follicle stimulating hormone (119 min). Preliminary carboh ydrate analysis showed recombinant human follicle stimulating hormone to contain high mannose and/or hybrid type, in addition to complex typ e carbohydrate chains, terminating with both alpha 2,3 and alpha 2,6 l inked sialic acids. These results demonstrate that recombinant human f ollicle stimulating hormone made in the Sp2/0 myeloma cells is sialyla ted, has a more basic isoform profile, and has a greater in vitro biol ogical potency compared to those of the pituitary human follicle stimu lating hormone.