Peanut component Ara h 8 sensitization and tolerance to peanut.
BACKGROUND
Isolated Ara h 8 sensitization is suggested to be associated with no or mild symptoms among peanut-sensitized subjects.


OBJECTIVE
We sought to investigate the occurrence of systemic reactions in children with isolated sensitization to Ara h 8.


METHODS
Participants were 144 children sensitized to Ara h 8 (≥ 0.35 kU(A)/L) but not to Ara h 1, Ara h 2, or Ara h 3 (<0.35 kU(A)/L). An open oral challenge with peanut was performed in those subjects who did not consume peanut regularly, and an extended IgE reactivity profile was obtained. If the child had a documented history of systemic reactions up to grade I anaphylaxis, double-blind, placebo-controlled food challenges were performed.


RESULTS
One hundred twenty-nine (89.5%) children were either peanut consumers or did not react to peanut challenge. Another 14 (9.7%) children experienced oral cavity symptoms at the first 2 but not subsequent challenge doses. At the time of the double-blind, placebo-controlled food challenge, 1 boy with a previous mild systemic reaction to peanut experienced lip swelling, stomach cramping, and objective tiredness. Reanalysis of IgE levels showed an increase in peanut IgE levels from 1.5 to 8.8 kU(A)/L, but IgE levels to Ara h 8 remained stable and IgE levels to Ara h 1, Ara h 2, and Ara h 3 were all still less than 0.35 kU(A)/L. The IgE level to Ara h 6 was 0.45 kU(A)/L.


CONCLUSIONS
Isolated Ara h 8 sensitization indicates tolerance to peanuts in almost all cases. However, sensitization against thus far unidentified determinants in peanut might cause symptoms in rare cases.
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. anna.asarnoj@ki.se
Anna
A
Asarnoj
Caroline
C
Nilsson
Jonas
J
Lidholm
Susanne
S
Glaumann
Eva
E
Östblom
Gunilla
G
Hedlin
Marianne
M
van Hage
Gunnar
G
Lilja
Magnus
M
Wickman
D000284:Administration, Oral; D000293:Adolescent; D000485:Allergens / Q000009:adverse effects / Q000276:immunology; D000707:Anaphylaxis / Q000150:complications / Q000276:immunology*; D001087:Arabinonucleosides / Q000009:adverse effects / Q000276:immunology*; D010367:Arachis / Q000009:adverse effects / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007108:Immune Tolerance; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D008297:Male; D021183:Peanut Hypersensitivity / Q000150:complications / Q000276:immunology*; D010919:Placebos; D012882:Skin Tests; D055815:Young Adult
D000485:Allergens; D001087:Arabinonucleosides; D010919:Placebos; D007073:Immunoglobulin E; C008099:hypoxanthine arabinoside