Baby hamster kidney cells producing a recombinant IgG-IL2 fusion protein were grown as spinner batch cultures in a protein-free medium, with cells immobilised in porous and non-porous supports at different support concentrations and agitation rates. Product quality, i.e., integrity, decreases up to 60% with the increase in agitation rate or support concentration and from porous to non-porous supports. LDH activity is a good indicator for the monitoring of product degradation, and thus product quality. Optimal conditions regarding titre of intact product were achieved at 60 rpm with 2 g porous support l(-1).