The purification of monoclonal antibodies anti-CD34 produced in hybridoma cells was accomplished by aqueous two phase extraction, using an integrated process that allowed to clarify and partially purify the produced mAb in just one step. The feasibility of using polyethylene-glycol (PEG)/dextran systems was studied at different ionic strengths (0-300 mM NaCl) and at different pH values (pH 3,4 and 7). The effect of molecular weight (MW) of PEG (3350 and 6000 Da) was also evaluated. For all the conditions studied, it was observed that antibodies partition preferentially to the PEG-rich phase, cells to the interface and soluble proteins to the bottom dextran-rich phase. The best recovery yield was obtain with an ATPS composed by 7% PEG 6000 Da, 5% dextran 500,000 Da, 150 mM NaCl at pH 3. In this system, it was possible to recover 84 +/- 6.5% IgG with 0.1 +/- 0.2 % of cells in the top phase. (C) 2014 Elsevier B.V. All rights reserved.