alpha gal allergy (red meat allergy)

Food Allergy

A Practice

Parameter

Update 2014

Part II

Suda Sibunruang, M.D.

Commins S. and Platts-Mills T. J Allergy Clin Immunol 2009;124:652-7Tripathi A. et.al. J Allergy Clin Immunol Pract 2014;2:259-65

α-gal oligosaccharide • Major blood group substance of non-primate mammals• Present on glycolipids and glycoproteins in meat

and organs of a wide range of mammals• Target of IgG antibodies, which are present in the serum

of all immunocompetent individuals

Commins S. and Platts-Mills T. J Allergy Clin Immunol 2009;124:652-7

N-acetylglucosamine GalactoseFucose

Comparison of mammalian blood group-related oligosaccharides

O’Neil B.et.al. J Clin Oncol 2007;25:3644-8

Picture from www.ephotopix.comAccess December 16, 2014

Chung C. et.al. N Engl J Med 2008;358:1109-17

Chung C. et.al. N Engl J Med 2008;358:1109-17

In most subjects who had a hypersensitivity reaction to cetuximab, IgE antibodies against cetuximab were present in serum before therapy.

The antibodies were specific for galactose-α-1,3-galactose

Tripathi A. et al. J Allergy Clin Immunol Pract 2014;2:259-65

Whether there were allergic diseases associated with IgE antibodies to alpha-gal ?

Identified a group of patients who had episodes of generalized urticaria, angioedema, or

recurrent anaphylaxis

Several patients had delayed anaphylaxis to red meat

Picture from www.washingtonpost.comAccess December 16, 2014

Delay anaphylaxis to red meat

• Delay symptoms for at least 2 hours

(most cases, 3 – 5 hours)

• All patients reported meat consumption before the onset of syndrome

• Many patients > 60 years old

(reported cases in children 5 years old)


Differential diagnosis


Cat- pork syndrome

Commins S. and Platts-Mills T. Curr Allergy Asthma Rep 2013;13:72–7

Differential diagnosis

• Reactions are rapid

(occur within 1 hr)

• Only after ingestion of pork


Cat- pork syndrome

Investigations

• Specific IgE to -gal, beef, pork, lamb and milk

(lack of IgE to chicken, turkey, and fish)

• Skin tests


Kennedy J. et.al. Pediatrics 2013;131:1545–52

Correlations of IgE to a-Gal and specific allergens

Commins S. et.al. J Allergy Clin Immunol 2009;123:426-33

SPT and ID test in patients with IgE antibodies to α-gal

SPT- commercially reagents1:20 wt/vol

ID - commercially reagents1:100 dilution (ie, 1:2000 wt/vol)


SPTs with commercially available reagents (Lt) and fresh meat extract (Rt)

Picture from www.healthunit.orgAccess December 16, 2014

Relevance of tick bites

http://www.healthunit.org/


States where anaphylactic reactions to cetuximab were reported in 2006


Reported prevalence of Rocky Mountain spotted fever

Tripathi A. et al. J Allergy Clin Immunol Pract 2014;2:259-65Data are from the Centers for Disease Control and PreventionWeb site (http://www.cdc.gov/

ticks/geographic_distribution.html#lone-star)


Patients with delayed anaphylaxis to red meat whose serum contained IgE antibodies to alpha-gal

Access from www.jamestownri.govDecember 16, 2014

These bites characteristically itch for 10 days or more !

http://www.jamestownri.gov/

Wolver S. et.al. J Gen Intern Med 2012;28:322–5

Commins S. and Platts-Mills T. Curr Opin Allergy Clin Immunol 2013;13:354–9

Why is there delay in response ?

• The only coherent explanation is that the oligosaccharide is absorbed in some form that enters the circulation slowly


Management

• Avoidance of “red meat”

• Avoiding tick bites

• Management of episodes


Avoidance of “red meat”

• Avoiding not only beef, pork, and lamb but also horse, goat, rabbit, and squirrel,includes organs from mammalian sources such as liver, intestine, heart, and kidney

• In addition, other mammalian products include lard, suet, gelatin, pork rinds, and dairy products


Management

• Avoidance of “red meat”

• Avoiding tick bites

• Management of episodes


Unknown aspects

• Why the tick bites induce such high levels of IgE antibody and why the response is specific for this oligosaccharide

• The basis for the delay in symptoms is not clear


Summary Statement 5

• Test for IgE antibodies specific for the immunogenic oligosaccharide galactose-alpha-1, 3-galactose (alpha-gal) in patients who report a delayed systemic reaction to red meat or unexplained anaphylaxis, particularly if they have a history of previous tick bites[Moderate; C Evidence]

Summary Statement 6

• Avoid all mammalian meats in patients with alpha-gal allergy because this oligosaccharide antigen is widely expressed in mammalian tissues[Moderate; C Evidence]

Thank you for your attention

alpha gal allergy (red meat allergy)

Health & Medicine