Skin Prick Testing
Nine peanut-allergic subjects and three non-allergic healthy controls
aged 19 to 29 years old were recruited to the Montreal Children’s
Hospital for Skin Prick Testing (SPT) after obtaining informed consent.
Subjects were considered allergic based on previous history suggestive
of immediate allergy to peanut and the presence of previous positive SPT
to peanut (wheal diameter greater than 7 mm), detection of
serum-specific IgE to peanut proteins (>0.35 kU/L) and/or a
positive oral food challenge to peanut.
Peanuts processed by roasting, autoclaving, roasting then autoclaving,
and autoclaving then roasting, along with raw peanuts, were further
processed into protein extracts as described above. Extracts of each
condition were diluted to equal concentrations equivalent to the
commercial standard peanut extract (Allergy Canada Limited, Thornhill,
ON, LOT No: 3467710) as measured by Bradford Assay. The SPTs were
conducted by placing a drop of each extract, as well as the standard
commercial extract, on the forearm and making a small scratch on the arm
using a solid bore needle. Saline diluent and Histamine (1mg/mL,
ALK-Abello Pharm., Inc., ON, Canada) were used as negative and positive
controls, respectively. After 10 minutes, the size of the wheal diameter
was measured (in mm). All skin tests were performed by an experienced
allergy nurse. Research Ethics Board (REB) approval was obtained from
the McGill University Health Centre (MUHC-REB 2020-5745).