Detection of human leucocytes by cyclic voltammetry and its application to monitoring of allergic reaction

Cyclic voltammetry was applied to the detection of human leucocytes and the monitoring of allergic reactions. A basal plane pyrolytic graphite electrode with attached leucocytes on a porous nitrocellulose membrane filter was employed as a working electrode. An anodic peak current appeared at 0·33 V versus the saturated calomel electrode (SCE) when the potential of the working electrode was scanned in the range of 0-1·0 V versus SCE. This peak current was attributed to the electrochemical oxidation of serotonin. When egg white was added to leucocytes obtained from patients who were allergic to egg, the peak current decreased owing to degranulation of leucocytes leading to serotonin release. The peak current decreased with increasing allergen concentration in the range of 5-50 μg ml^-1. Leucocytes did not respond to other allergens such as soybean, milk and dinitrophenylated bovine serum albumin (DNP-BSA).