Food allergy and anaphylaxis – 2044. Component resolved allergen sensitzation profiles in shrimp allergy in the tropics

Background

Shellfish allergy is one of the commonest food allergies in the tropics.

Objectives

To evaluate the sensitization profile to a panel of allergens of dust mite(DM), shrimp and tropomyosin allergens in a cohort of shrimp allergy (SA) patients.

Methods

Serum allergen-specific IgE of 105 subjects were quantified using ImmunoCAP and ImmunoCAP ISAC biochips. The subjects were classified based on a convincing clinical history and food challenge testing (FC) (dose=70g) to Penaeus monodon and Litopenaeus vannamei. Group1A: Either SA with FC positive to either shrimp (n =22) or SA admitted to emergency departments for severe reactions but no FC performed (n=14) (total n=36); and Group1B: Reported SA with FC negative (n=31). Group2: Shellfish tolerant DM sensitized controls (n= 38).

Results

All 105 subjects but one were sensitized to at least one of 3 DM tested (Dermatophagoides pteronyssinus, Dermatophagoides farina, Blomia tropicalis), with highest sensitization rates to Blo t 5 followed by Der f 1. DM and shrimp tropomyosin showed high correlation (p<0.001). Group1A had higher rates of sensitization to tropomyosins compared to Group1B (Der p 10 [33.3%vs9.7%], and Pen m 1 [33.3%vs9.7%], p<0.037); and to Group2 (Blo t 10 [19.4%vs0%], Pen m 1 [33.3%vs5.3%], Pen I 1 [27.8%vs5.3%], Lit v 1 [22.2%vs5.3%], p<0.05). Sensitization to Lit v 2 were higher in Group1A (22.2%) compared to Group1B (6.5%) and Group2 (5.2%) (p<0.093). The sensitization rates to Lit v 3, 4 were low (<10%). A positive test for a combination of shrimp (ImmunoCAP f24)+any tropomyosin+any shrimp allergens gave the highest sensitivity(81.8%) to distinguish FC positive from negative subjects but had a low specificity of 24.1%. The specificity was highest (93.1%) when using a positive test for Der p 10 or any shrimp tropomyosin, but sensitivity was low (31.8%).

Conclusions

Tropomyosins are highly cross reactive across species and is significantly associated with SA in the tropics. ISAC Immunocap improved the accuracy to detect FC+ve SA.