The interaction of a mammalian cell culture broth with two commercially available adsorbents for the use in expanded bed adsorption (EBA) has been studied. A cation exchange resin (Streamline SP) and an affinity adsorbent (Streamline rProtein A) were compared with regard to adsorption of hybridoma cells during sample application as well as potential cell damage. The results showed that hybridoma cells interact significantly with an expanded bed of cation exchange adsorbents but not with the Protein A adsorbent. After application of 17-20 sedimented bed volumes a saturation of the Streamline SP resin with cells was noted. With both adsorbents no measurable cell damage was found acid IgG, was recovered in approximately 95% yield. The capacity for IgG, adsorption at 3% breakthrough was 2.7 mg IgG(1)/ml Streamline rProtein A at a constant fluid velocity of 380 cm/h and 1.0 mg IgG(1)/ml Streamline SP at 215-240 cm/h fluid velocity.