Q:

3/6/2013
Please clarify the family in which salmon and tuna belong. Are they considered a whitefish or are they in a separate category? Thank you for your time.

A:

Thank you for your inquiry.

Tuna and salmon belong to different families of fish. Tuna is a member of the Scombridae family of fish. Salmon is in the Salmonidae family. However, I assume you are interested in potential allergen cross-reactivity between salmon and tuna, and family per se doesn't always define cross-reactivity. Unfortunately, cross-allergenicity between fish is quite complex and has not, to my knowledge, been conclusively defined. Copied for you below is an abstract of an article that has looked at this issue, and I think that the operative word in the conclusion is “probably.” Also the issue of cross-reactivity between fish is discussed in detail in the classic article looking at clinical cross-reactivity between foods by Sicherer (1). This article should be readily accessible to you through the allergist with whom you work via a subscription to the Journal of Allergy and Clinical Immunology. The point being, from reading this article, is that there is unpredictability as far as cross-reactivity is concerned. The only true test is an oral challenge.

However, in general, it would be expected that cross-reactivity between tuna and salmon is relatively rare, with salmon probably more commonly cross-reactive with cod, and tuna more commonly cross-reactive to other members of the scombroid family. However, these cross-reactivity patterns are only guidelines, and cannot be taken literally because there are definite exceptions. For example, in one Italian investigation, in children sensitive to cod, over 50% showed sensitivity to tuna (2).

In summary, salmon and tuna belong to different families of fish. However, the fact that they are in separate families does not rule out potential cross-reactivity, and there are no definitive data which would allow you to predict with accuracy as to whether or not clinical cross-reactivity would occur. Testing for specific IgE would of course be helpful, but an oral challenge would be the only completely reliable test to determine such cross-reactivity.

Thank you again for your inquiry and we hope this response is helpful to you.

J Allergy Clin Immunol. 2005 Dec;116(6):1314-20. Epub 2005 Oct 3.
Allergy to fish parvalbumins: studies on the cross-reactivity of allergens from 9 commonly consumed fish.
Van Do T, Elsayed S, Florvaag E, Hordvik I, Endresen C.
Source
Allergy Research Group, Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway.
Abstract
Background: Fish-hypersensitive patients can probably tolerate some fish species while being allergic to others.
Objective: To determine the allergenic cross-reactivity between 9 commonly edible fish: cod, salmon, pollack, mackerel, tuna, herring, wolffish, halibut, and flounder.
Methods: Sera from 10 patients allergic to fish and rabbit antisera against 3 parvalbumins (Gad c 1, Sal s 1, and The c 1) were used. Cross-reactivity was investigated by SDS/PAGE and IgE immunoblotting, IgG ELISA, IgE ELISA inhibition, and skin prick test (SPT).
Results: Cod (Gad c 1), salmon (Sal s 1), pollack (The c 1), herring, and wolffish share antigenic and allergenic determinants as shown by immunoblots and IgE ELISA, whereas halibut, flounder, tuna, and mackerel displayed lowest cross-reactivities. The highest mean IgE ELISA inhibition percent of 10 sera was obtained by Gad c 1, followed by The c 1, herring, Sal s 1, wolffish, halibut, flounder, tuna, and mackerel with the least inhibition. Nine of the 10 patients showed positive SPT to cod, salmon, and pollack; 8 patients reacted to recombinant (r) Sal s 1. Positive SPTs to rGad c 1 and rThe c 1 were demonstrated in 1 patient.
Conclusion: Gad c 1, Sal s 1, The c 1, herring, and wolffish contained the most potent cross-reacting allergens, whereas halibut, flounder, tuna, and mackerel were the least allergenic in the current study. The latter could probably be tolerated by some of the tested patients.

References:
1. Sicherer SH. Clinical implications of cross-reactive food allergens. J Allergy Clin Immunol 2001; 108:881-890.
2. de Martino, M; Novembre, E; Galli, L; de Marco, A; Botarelli, P; Marano, E; Vierucci, A. Allergy to different fish species in cod-allergic children: In vivo and in vitro studies. J Allergy Clin Immunol; 1990; 86: 909-914.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology