The fluidized bed affinity recovery of C595 diabody fragment (dbFv) from Escherichia coli lysates in an integrated system mode has been investigated. An amino acid epitope sequence, RPAP was immobilized onto Upfront adsorbent (rho = 1.35 g cm(-3)). The recovery performance of various feedstocks (clarified, unclarified and concentrated unclarified feedstocks) were compared and evaluated. It was demonstrated that the values of operational productivity for clarified and unclarified feedstock were 198.18 and 129.11 mg L(-1), respectively. A relatively high elution yield (87-93%) was achieved for all types of feedstock evaluated. (C) 2011 Elsevier BM. All rights reserved.