LB004 - EVALUATION OF HISTAMINE-50-SKIN PRICK TEST (HIS-50-SPT), PLASMA HISTAMINE (HIS) AND SERUM DIAMINE OXIDASE (DAO) WITH DOUBLE-BLIND, PLACEBO-CONTROLLED HISTAMINE PROVOCATION (DBPCHP) TO DIAGNOSE HISTAMINE INTOLERANCE (HIT)

LB004

EVALUATION OF HISTAMINE-50-SKIN PRICK TEST (HIS-50-SPT), PLASMA HISTAMINE (HIS) AND SERUM DIAMINE OXIDASE (DAO) WITH DOUBLE-BLIND, PLACEBO-CONTROLLED HISTAMINE PROVOCATION (DBPCHP) TO DIAGNOSE HISTAMINE INTOLERANCE (HIT)

C. Leung^1,*, M. F. Tang¹, N. S. Cheng¹, P. F. Li¹, N. A. Ngai², O. M. Chan¹, A. S. Y. Leung^1,3, C. Y. Y. Wai¹, T. F. Leung¹

¹Department of Paediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, ²Department of Paediatrics, Prince of Wales Hospital, Prince of Wales Hospital, ³Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR

Rationale: HIS-50-SPT, where wheal reaction to HIS was measured at 50 minutes instead of 15 minutes after the prick, plasma HIS and serum DAO levels are potential diagnostic biomarkers for HIT. The gold standard to diagnose HIT is DBPCHP. This study compared results of HIS-50-SPT, plasma HIS and serum DAO levels against DBPCHP for HIT diagnosis in a Chinese population.

Methods: Eighty-six Chinese subjects (67.4% female, median age 32.2, interquartile range 23.6 – 38.2) undertook DBPC food challenge of seafood (fish or shrimp) with HIS-50-SPT done participated further HIT diagnosis tests. Subjects followed a 2-week low-HIS diet guided by a dietitian and were randomised to receive active (coconut-ginger pudding containing two doses of histamine hydrochloride at 0.5 mg/kg and 1.0 mg/kg body weight) or placebo (coconut-ginger pudding) on two days, within one week. Subjects were offered a low-HIS breakfast and lunch, serving puddings as dessert after each meal. Subjective and objective parameters were recorded at 0, 20, 40 and 100 minutes after each dose. Venous blood was taken at i) before and after low-HIS diet at recruitment, and ii) on each challenge day at baseline and 40 minutes after dose 2 if uneventful, or at the time point where subjects developed symptoms of HIT. Plasma histamine and serum DAO concentrations were measured by enzyme-linked immunosorbent assay (Immunodiagnostik AG, Bensheim, Germany).

Results: Seven (8.1%) subjects failed DBPCHP hence had HIT. Of these, four (57.1%) were positive for HIS-50-SPT (wheal size ≥3mm), which was not significantly associated with failed DBPCHP (P=0.497^a). At recruitment, median plasma HIS was lower yet insignificant, 0.21 vs. 0.01 ng/ml between HIS tolerant (n=71) and intolerant (n=7) group (P=0.07^b). Median serum DAO was 6.13 vs. 6.91 U/ml between HIS tolerant (n=72) and intolerant (n=7) group (P=0.566^b). No significant differences were found between the two groups for change in plasma HIS (Active: P=0.167^c vs. Placebo: P=0.101^c) and serum DAO (Active: P=0.268^c vs. Placebo: P=0.652^c) upon provocation.

Conclusion: DBPCHP is the most reliable way to diagnose HIT, which was uncommon among Chinese subjects with suspected seafood allergy. (funded by Health and Medical Research Fund [reference 09202866], Hong Kong SAR Government). 

References: ^a analysed by multivariate analysis by binary logistic regression adjusted for age and gender

^b analysed by linear regression adjusted for age and gender

^c analysed by General Linear Model (GLM) Repeated Measure, adjusted for age and gender

Disclosure of Interest: None declared