Anaphylaxis and possible meat allergy
I am following a 22 year-old woman with recurrent episodes of "idipathic" anaphylaxis and would like your input on how to move forward diagnostically. As a young child, she had cold induced urticaria (did not have an "ice cube" test at that time). She also had a cutaneous reaction to latex (recent latex IgE was 0.12 kU/L). I first saw her this past September when she had an anaphylactic reaction (hives and vomiting) after eating meal that included foods she had previously tolerated. There were no exacerbating factors (EtOH, exercise, NSAID). Two weeks later she had a spontaneous episode of diffuse hives, vomiting and facial swelling. Very recently, she had a third episode. Within minutes of eating a meal that included beef and barley, she developed abdominal pain, flushing on her face and chest, vomiting, hoarseness and difficulty breathing. She injected herself with epinephrine and when she arrived in the ER, her vision was "fuzzy." I do not have documentation of her vital signs on arrival. She was normotensive but this was recorded after she took Epi.
I ordered labs which showed elevated levels of alpha gal IgE to lamb (4.05) and pork (3.53). She was negative to beef. She does not either lamb or pork and has no history of a tick bite or exposure to areas where the Lone Star Tick is prevalent. A 24-hour urine histamine level was elevated at 143 (0-65). Urine catecholamines were normal as was a serum tryptase level (4.5). and chromogranin A (< 1.0). She had a latex specific IgE level of 0.12. She had urinary prostaglandin D2 measurement of 119 (no normal values were listed). I don't know what to make of the elevated alpha-gal levels. I would be very interested in your opinion on how you would treat this patient and what, if any, additional tests should be done.
I am grateful to Scott Commins MD, PhD for his response to your question.
It seems to me that this patient should have a test for IgE to cat serum albumin. The positive result to pork and lamb with a negative IgE to beef makes me suspicious that alpha-gal syndrome (AGS) is not the answer here. If positive, IgE to cat serum albumin would implicate pork-cat syndrome. This rare allergy is due to cross-reactivity between cat serum albumin and serum albumin in pigs. The reactions can occur much more rapidly than AGS and can include many of the same mammalian meat (beef, lamb, boar, venison, etc). Typically, patients who develop pork-cat syndrome are pet owners with multiple cats and/or dogs at home – interestingly, most do not report inhalant allergy symptoms to their pets.
Posthumus J, James HR, Lane CJ, Matos LA, Platts-Mills TA, Commins SP. Initial description of pork-cat syndrome in the United States. J Allergy Clin Immunol. 2013 Mar;131(3):923-5.
I hope this is helpful to you and your patient.
Jacqueline A. Pongracic, MD, FAAAAI