Ultrasensitive and rapid immuno-detection of human IgE anti-therapeutic horse sera using an electrochemical immunosensor.

The researchers have developed an ultra-sensitive, amperometric immunosensor that can rapidly detect antibodies (specifically IgE) in humans allergic to therapeutic horse serum, used in passive antibody therapies like antivenom. This development may help identify individuals at risk of adverse reactions prior to such therapy.

Development of an Electrochemical Immunosensor

• The study focused on developing a device that can identify hypersensitive individuals before they undergo passive antibody therapy. Passive antibody therapy refers to treatments where individuals receive antivenoms and the process can induce allergic reactions in certain people.
• The developers relied on an amperometric immunosensor to detect reactive human IgE – a type of antibody that’s often associated with allergic reactions.
• In this process, whole horse IgG3 (hoIGg3) is immobilized onto the surface of either carbon or gold screen-printed electrodes. This is done using a cross-linking solution of glutaraldehyde on a layer of a biocompatible polymer, chitosan.

Application of Sera and Detection Method

• Next, sera from individuals known to exhibit allergic responses to hoIgG3 or from non-allergic individuals is applied to the sensor. The term ‘sera’ refers to the clear part of the blood that’s left after coagulation – it contains antibodies.
• The immunosensor then detects bound human IgE (or humIgE) using an anti-humIgE antibody, and the presence of these antibodies is quantified through an amperometric determination. An amperometric determination is a process where the current resulting from an electrochemical reaction is measured.
• This determination process is carried out by tracking the electrochemical reduction of quinone, which is generated from hydroquinone as a potential of 25mV is applied.

Evaluation of the Immunosensor

• The optimal configuration of the immunosensor was capable of detecting reactive humIgE at a dilution of 1:1800 of the human sera, which suggests a detection limit of 0.5 pg/mL. This level of sensitivity is considered extremely high.
• Stability testing of the immunosensor showed promising results, maintaining specificity and performance through 20 cycles of scanning.
• Through these results, the researchers concluded that the new immunosensor successfully detects humIgE antibodies that react against hoIgG3, enabling the early identification of individuals at risk of allergic reactions to therapeutic antivenom preparations sourced from horses.