Clinical symptoms reported by Teuber et al. (1998) [206] include hypotension or laryngeal oedema with or without nausea, vomiting, generalized urticaria and asthma. All had life threatening systemic allergic reactions to walnut and 2/16 individuals had had systemic reactions on skin prick test with walnut extract.

In a second study, 11 of 20 Rosaceae fruit allergic patients without birch pollenosis reported symtoms with walnut. 7 patients had urticaria (one with asthma) and 4 had oral allergy syndrome to walnut (Asero et al. 2002 [667]).

Asero et al. (2004) [840] also reported gastric pain, severe asthma, urticaria and collapse in an 11 year old boy on consumption of walnut.

Only 1% of the 94 patients who could tolerate walnut had SPT ≥8mm. However, there was no correlation between SPT size and severity of worst reaction for walnut allergic patients.

Asero et al. (2002) [667] reported 14/20 patients gave a positive SPT to walnut. Clinical history suggested that there were 3 false negatives and 6 false positives

Asero et al. (2004) [840] report a wheal of 15 mm to both walnut and hazelnut with weaker 4 mm wheals from peanut and peach in 1 patient.

CAP (Teuber et al. 1998 [206]), ELISA (Asero et al. 2002 [667]; Asero et al. 2004 [840])

Teuber et al (1998) [206] studied sera from 16 walnut allergic patients, aged 9-55 years.

Sera from 17 of 20 Rosaceae fruit allergic patients without birch pollenosis (Asero et al. 2002 [667]).

Serum from an 11-year old boy (Asero et al. 2004 [840]).

Of sera from 16 patients, 3 gave CAP Class 2, 7 class 3, 2 class 4 and 4 class 5 (Teuber et al. 1998 [206]).

Sera from 12/17 patients showed positive IgE binding with walnut extract. Clinical history suggested that there were 4 false negatives and 5 false positives (Asero et al. 2002 [667]).

Serum from one patient showed strong binding with walnut extract and slightly weaker with hazelnut (Asero et al. 2004 [840]).

Teuber et al (1998) [206] transferred proteins to 0.22 µm nitrocellulose membranes (Schleicher & Schuell, Keen, N.H.) overnight at 35 V by using a TE 42 Transphor Electro-Transfer Unit (Hoefer Scientific Instruments). The blots were blocked in a mixture of PBS and 3% (w/v) nonfat dry milk for 30 minutes and then incubated overnight at room temperature in sera diluted 1:5 in PBS/milk. The following day, strips were washed for 20 minutes three times in PBS/0.05% Tween-20 at room temperature and incubated overnight with ¹²⁵I-antihuman IgE (Sanofi Diagnostics/Pasteur). The strips were again washed, dried, and exposed to x-ray film for 18 to 72 hours at –70° C.
In an abstract Teuber et al. (1999) [940] note that the use of non-ionic detergents to remove SDS before adding sera is critical for observing binding to Jug r 1 and some other allergens.