Walnut allergen Jug r 4 in allergic adults
What it found
In 55 adults who had a walnut food challenge, 10 were sensitive to the walnut protein Jug r 4.
Nine of those 10 had a positive challenge, but most were also sensitive to other walnut proteins.
What they found
Studies in people
Jug r 4 sensitivity
Of the 55 adults, 10 were sensitive to Jug r 4 on the EUROLINE test and 5 on immunoblot. All 5 positive on immunoblot were also positive on EUROLINE.
Challenge outcomes
Nine of the 10 Jug r 4 sensitive adults had a positive walnut challenge. One had a negative challenge.
Test performance
The authors report that the test for Jug r 4 had a sensitivity of 27%, specificity of 95%, positive predictive value of 90% and negative predictive value of 47%.
Co-sensitization
All 10 Jug r 4 sensitive adults were also sensitive to other walnut components, mostly Jug r 1. None were sensitive to Jug r 4 alone.
Other 11S globulins
Among the 10 Jug r 4 sensitive adults, 6 were also sensitive to hazelnut Cor a 9, and some to cashew, soy and peanut 11S globulins. The authors say this may be due to cross-reactivity.
Other findings
ImmunoCAP extract
Lab analysis showed that the walnut extract used in the ImmunoCAP test does not contain Jug r 4 or Jug r 3, but does contain Jug r 1 and Jug r 2.
What the authors conclude
“Walnut 11S globulin Jug r 4 is a relevant minor allergen, recognized by 27% of walnut allergic adults.”
Also in their conclusions
- They conclude that walnut 11S globulin Jug r 4 is a relevant minor allergen, recognized by 27% of walnut allergic adults.
- They state that it has a high positive predictive value of 90% for walnut allergy.
- They note that specific IgE against Jug r 4 occurred mostly with concomitant sensitization to other walnut components, mainly Jug r 1.
How it was done
The known walnut allergens Jug r 1, 2 and 3 did not explain all cases of walnut allergy, so the authors looked for other walnut proteins that allergic adults react to.
They prepared walnut extracts in the lab and screened blood from 8 walnut allergic adults to find proteins that IgE antibodies bind to. Then they tested blood from 55 adults who had a walnut food challenge, 33 allergic and 22 tolerant, for sensitivity to Jug r 4 using two lab methods.
What it can’t tell you
- This study cannot show whether being sensitive to Jug r 4 alone causes walnut allergy, because almost all sensitive people were also sensitive to other walnut proteins.
- The results are from adults who had a walnut challenge, so they may not apply to children or to people not tested this way.
Who paid
- Authors work at
- University Medical Center Utrecht, The Netherlands; Magna Graecia University of Catanzaro, Italy
The paper
- Title
- A subset of walnut allergic adults is sensitized to walnut 11S globulin Jug r 4
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Blankestijn MA, den Hartog Jager CF, Blom WM, et al (2018). A subset of walnut allergic adults is sensitized to walnut 11S globulin Jug r 4. Clinical and experimental allergy. doi:10.1111/cea.13208Free full textPubMed 29904971DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error