D3.11 - Identification of allergens in Chicken and Rabbit meat, a case report

Introduction: 

Allergic reactions to meat have historically been considered rare, however, is being increasingly recognized in subjects of all ages.

The aim of the study was to determine possible sensitisation to chicken and rabbit meat and to molecularly characterise their allergens.

We present a 75-year-old woman, who reported experiencing immediate urticaria after eating poultry and rabbit meat over the past couple of years. The urticaria subsides immediately afterwards.

Methods: 

We performed skin prick-prick tests with samples provided by the patient: chicken and rabbit meat. sIgE against chicken and rabbit were also assed. 

For the in vitro immunological study, protein extracts from chicken and rabbit meat were prepared. The samples were quantified using the Bradford method, separated by SDS-PAGE, and transferred to a membrane. Immunoblotting was performed using HRP-conjugated mouse anti-human IgE antibody to detect proteins recognized by the patient's serum IgEs. 

An inhibition immunoblot with rabbit meat was performed to determine whether there was cross-reactivity between rabbit and chicken meat. 

Results: 

Skin Prick-Prick tests showed no reactivity to chicken and rabbit meat due to inhibition of histamine control. Total IgE was elevated (3466 UI/ml), and sIgE to chicken (0.08 kU/L) and rabbit (0.19 kU/L) were negative. 

Western blot analysis of rabbit meat identified prominent IgE-reactive protein bands at approximately 57 kDa , 47 kDa  and 27-25 kDa compatible with albumin, tropomyosin (Ory c TM) and lipocalin (Ory c 4), respectively.  Western blot analysis of chicken meat showed a prominent IgE-reactive protein band at approximately 47 kDa compatible with a β-enolase (Gal d 9).No other major reactive bands were observed. 

To determine cross-reactivity, an inhibition immunoblot was performed using rabbit meat, revealing that the 47 kDa band from chicken disappeared. Thus, we performed an in silico analysis and determined that the beta-enolases of the two species (chicken and rabbit) are structurally identical. 

Conclusions: 

The patient is sensitized to rabbit and chicken meat. Her serum reacts with a 47 kDa protein common for both allergenic extracts. Inhibition immunoblot with rabbit meat. strongly supports cross-reactivity through the 47 kDa band. This protein presumably  corresponds to the β‑enolase, which is consistently expressed in rabbit and chicken muscle tissue. We present the first reported case of an allergy to rabbit meat caused by β-enolase.