Peter Vadas




Additional Research Specialties

Anaphylaxis, peanut allergy, platelet activating factor, PAF acetylhydrolase, induction of oral tolerance.

Research Activities

  • Secretion of peanut protein in breast milk of lactating women
  • Use of activated charcoal in treating peanut-induced allergic reactions
  • Role of platelet activating factor (PAF) and PAF acetylhydrolase in severe and fatal anaphylaxis
  • Mechanism of action of epinephrine as a rescue medication in acute anaphylaxis
  • Risk factors that predispose to severe anaphylaxis
  • Undeclared peanut protein in prepared foods imported into Canada
  • Catemenial anaphylaxis: response to treatment
  • Anaphylactic reactions follow stereotypic sequences of symptoms. Exploring the pathophysiologic basis

The Allergy and Immunology Clinic’s research programs are broad in scope and have resulted in innovative research discoveries that can support patients with diseases that require treatment to live normal lives.

Faculty members are actively engaged in research at basic, translational and clinical levels with meaningful outputs in the areas of: Adverse Drug Reaction and Rapid Drug Desensitization Program, Primary Immune Deficiencies, Mast Cell Disorders, C1 Esterase Inhibitor Deficiency, Chronic Spontaneous Urticaria (CSU). Notable multidisciplinary collaborations within the clinic include: Cholinergic Urticaria with Anaphylaxis, Mast Cell Activation Syndrome, Platin Allergy in Patients with Advanced Ovarian Cancer.

The Adverse Drug Reaction and Rapid Drug Desensitization Program was established by the Allergy and Immunology Clinic in 2001 to quickly identify and treat hospitalized patients who are experiencing adverse reactions, thereby reducing morbidity, length of stay and attendant costs. The Rapid Drug Desensitization (RDD) Program was established when this form of therapy was in its infancy. It is now a routine, established treatment that allows patients to safely receive a wide range of anti-microbial, chemotherapeutic and non-antimicrobial therapies to drugs which had caused life-threatening allergic reactions. RDD is routinely used in patients with cystic fibrosis who are experiencing an antibiotic allergy, and in patients with acute coronary syndromes and Aspirin allergy, amongst others. This program is the only one of its kind in Canada.

Significantly, the Allergy and Immunology Clinic has advanced clinical research in milk and peanut anaphylaxis using novel epicutaneous desensitization techniques, expertise in primary immune deficiency and gamma-globulin replacement treatment.  The team has also lead international collaborations, such as sequestered auto-antigens in inducible forms of physical urticaria (ie: cholinergic, exercise and cold-induced urticaria).  Recent collaborations with basic scientists have resulted in an uptake of evidence-based care into clinical practice and health policy. A high-impact publication on platelet activating factor (PAF) synthesis and release during mast cell activation and degranulation has served as a nidus for ongoing research into the mechanisms leading to severe and fatal anaphylaxis. In patients with acute anaphylaxis, serum PAF levels correlate with anaphylaxis severity.

The Allergy and Immunology Clinic is developing a clinical trial of PAF receptor blockers as rescue therapy in acute anaphylaxis in conjunction with the Food Allergy and Anaphylaxis Program at the Hospital for Sick Children.

Recent Publications

  1. Gotlib, J, Castells, M, Elberink, HO, Siebenhaar, F, Hartmann, K, Broesby-Olsen, S et al.. Avapritinib versus Placebo in Indolent Systemic Mastocytosis. NEJM Evid. 2023;2 (6):EVIDoa2200339. doi: 10.1056/EVIDoa2200339. PubMed PMID:38320129 .
  2. Carter, MC, Park, J, Vadas, P, Worm, M. Extrinsic and Intrinsic Modulators of Anaphylaxis. J Allergy Clin Immunol Pract. 2023;11 (7):1998-2006. doi: 10.1016/j.jaip.2023.05.015. PubMed PMID:37230384 .
  3. Jiang, M, Vadas, P. Hereditary alpha-tryptasemia and complete deletion of exon 8 of the c-kit gene in patients with mast cell activation syndrome. Leuk Lymphoma. 2023;64 (7):1348-1351. doi: 10.1080/10428194.2023.2203286. PubMed PMID:37086476 .
  4. Upton, JEM, Grunebaum, E, Sussman, G, Vadas, P. Platelet Activating Factor (PAF): A Mediator of Inflammation. Biofactors. 2022;48 (6):1189-1202. doi: 10.1002/biof.1883. PubMed PMID:36029481 .
  5. Upton, JEM, Hoang, JA, Leon-Ponte, M, Finkelstein, Y, Du, YJ, Adeli, K et al.. Platelet-activating factor acetylhydrolase is a biomarker of severe anaphylaxis in children. Allergy. 2022;77 (9):2665-2676. doi: 10.1111/all.15308. PubMed PMID:35396721 .
  6. Slapnicar, C, Lebovic, G, McParland, A, Dozois, M, Vadas, P. Reproducibility of Symptom Sequences Across Episodes of Recurrent Anaphylaxis. J Allergy Clin Immunol Pract. 2022;10 (2):534-538.e1. doi: 10.1016/j.jaip.2021.11.031. PubMed PMID:34933152 .
  7. Lee, EY, Song, C, Vadas, P, Morgan, M, Betschel, S. Characterizing telemedicine use in clinical immunology and allergy in Canada before the COVID-19 pandemic. Allergy Asthma Clin Immunol. 2021;17 (1):131. doi: 10.1186/s13223-021-00635-1. PubMed PMID:34903277 PubMed Central PMC8667525.
  8. Varghese, A, Paul, T, Kim, H, Van Uum, S, Vadas, P, Azzola, A et al.. Effect of omalizumab for autoimmune progesterone dermatitis refractory to bilateral oophorectomy: a case report. Allergy Asthma Clin Immunol. 2021;17 (1):58. doi: 10.1186/s13223-021-00561-2. PubMed PMID:34120629 PubMed Central PMC8201679.
  9. Du, YJ, Gonzalez-Delgado, P, Vadas, P. Food protein-induced enterocolitis syndrome: Not just in children. Ann Allergy Asthma Immunol. 2021;127 (3):291-292. doi: 10.1016/j.anai.2021.05.029. PubMed PMID:34082126 .
  10. Lee, EY, Freedman, O, Castells, M, Vadas, P. Delayed hypersensitivity reactions to multiple aromatase inhibitors followed by successful desensitization to letrozole. Ann Allergy Asthma Immunol. 2021;127 (3):378-379. doi: 10.1016/j.anai.2021.05.007. PubMed PMID:34004279 .
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Affiliations & Other Activities

  • Head, Allergy and Clinical Immunology, St. Michael’s Hospital
  • Medical Advisory Board, Anaphylaxis Canada
  • Scientific Advisory Committee, National Peanut Board
  • Past chair, Anaphylaxis Committee, American Academy of Allergy and Clinical Immunology
  • Past chair, Anaphylaxis Committee, Canadian Society of Allergy and Clinical Immunology
  • Executive, Allergy, Asthma and Immunology Society of Ontario