1 January 2011

Commercial ELISA kits made by Enzo Life Sciences that detect Hsp70 are most often used by authors of papers that appear in Cell Stress & Chaperones. Our assessment is that there are likely to be three kits in existence.  The oldest is Stressgen kit EKS-700 that contains an anti-Hsp70A1A antibody for detection that reproducibly recognizes human, native eHsp70 in plasma and serum.  The behavior of this antibody suggests that it recognizes an epitope shared by intracellular and extracellular Hsp70.  Starting in 2005, when Assay Designs and Stressgen merged, a new detection antibody was produced, tested and packaged as kit EKS-700B.  Both kits recognized similar levels of Hsp70A1A in cell lysates but the new detection antibody did not reproducibly recognize eHsp70.  Therefore, according to their products manager, Assay Designs certified kit EKS-700B only for cell lysates.  Subsequently, Assay Designs produced a new anti-Hsp70 antibody that detects reproducibly levels of eHsp70. This detection antibody is packaged in kit ADI-EKS-715 (Enzo Life Sciences) and it is now the certified kit for detection of eHsp70 in plasma and serum of human, mouse or rat origin (90 pg/ml sensitivity).  ADI-EKS-700B kit is certified for use in detection of Hsp70 in cell lysates and tissue of human, mouse or rat origin (200 pg/ml sensitivity).

An immediate problem that sometimes arises when manuscripts are submitted for review containing measurement data for eHSP70 is failure to identify the ELISA kit used.  With the changes in the HSP70 kits that have occurred, it is necessary to have the kit number and the date purchased to determine if the appropriate kit was used.  Also, it is essential to know the source of the samples used as a source of Hsp70 and how they were prepared.   Among the Enzo kits, we recommend to authors to use only kit EKS-715 for measurement of eHsp70.

Published in: Distinguishing integral and receptor-bound heat shock protein 70 (Hsp70) on the cell surface by Hsp70-specific antibodies.  Multhoff, G. and Hightower, LE.  2010.  Cell Stress Chaperones, DOI 10.1007/s12192-010-0247-1.