Cellulose as an inert matrix for presenting cytokines to target cells: production and properties of a stem cell factor-cellulose-binding domain fusion protein

A chimaera of stem cell factor (SCF) and a cellulose-binding domain from th e xylanase Cex (CBDCex) effectively immobilizes SCF on a cellulose surface. The fusion protein retains both the cytokine properties of SCF and the cel lulose-binding characteristics of CBDCex. When adsorbed on cellulose, SCF-C BDCex is up to 7-fold more potent than soluble SCF-CBDCex and than native S CF at stimulating the proliferation of factor-dependent cell lines. When ce lls are incubated with cellulose-bound SCF-CBDCex, activated receptors and SCF-CBDCex co-localize on the cellulose matrix. The strong binding of SCF-C BDCex to the cellulose surface permits the effective and localized stimulat ion of target cells; this is potentially significant for longterm perfusion culturing of factor-dependent cells. It also permits the direct analysis o f the effects of surface-bound cytokines on target cells.