WHOLE BLOOD ROBOTIC CHOLINESTERASE ASSAY FOR ORGANOPHOSPHATE EXPOSURE - TESTING SOLDIERS, FIRST RESPONDERS, AND CIVILIANS IN THE FIELD AND LABORATORY

Abstract

Abstract : Exposure to organophosphate (OP) chemical warfare agents (CWAs), pesticides, anesthetics, drugs such as cocaine, and a variety of therapeutic drugs including donepezil or rivastigmine for Alzheimer's disease reduces red blood cell acetylcholinesterase (RBC-AChE) or serum butyrylcholinesterase (BChE) activity. The activity of RBC-AChE and BChE can be used as potential biomarkers of suppressed and/or heightened function in the central and peripheral nervous systems. For instance, the toxicity of pesticides is well documented in humans. Therefore, blood cholinesterase (ChE) activity can be exploited as a tool for confirming exposure to these agents and possible treatments. Yet it is the OP CWAs that are some of the most potent and irreversible inhibitors that can produce excessive accumulation of acetylcholine, and a cholinergic crisis in man leading to paralysis and ultimately death. Current assays for measurement of erythrocytebound acetylcholinesterase (RBC-AChE) and serum butyrylcholinesterase (BChE, pseudocholinesterase) require several labor-intensive processing steps, suffer from wide statistical variation, and inter-laboratory comparison is often difficult. Techniques currently used include the Ellman and microEllman microtiter method, radiometric, amperometric, and delta (delta) pH (modified Michel protocol) used by the U.S. Army's Cholinesterase Reference Laboratories (CRL). Such methods determine only the serum BChE or RBC-AChE, and require the use of specific ChE inhibitors or sample processing such as centrifugation.