Canadian Allergy & Immunology Today

Secondary Hypogammaglobulinemia

Vy H.D. Kim, MD — Mon, 23 Sep 2024 00:00:00 +0000

Secondary hypogammaglobulinemia (SHG) is characterized by reduced immunoglobulin levels due to extrinsic causes, such as a medication or an acquired disease process, resulting in decreased immunoglobulin production or increased immunoglobulin loss. Most published reports of SHG refer to IgG hypogammaglobulinemia and data on isolated IgA or IgM hypogammaglobulinemia is limited. The common causes of SHG include medications, hematological malignancies, and conditions associated with protein loss. Hypogammaglobulinemia can increase the risk of infection, morbidity and mortality, particularly in patients who may already be immunocompromised due to their associated condition or use of immunosuppressive therapies. With growing use of immunosuppressive or immunomodulatory treatments that affect B-cells, it is increasingly important to assess and monitor for SHG. Treatment of the underlying condition or removal of the extrinsic factor often results in resolution of the SHG. A subset of patients presenting with autoimmune or malignant conditions can have a primary immunodeficiency (PID) or primary immune regulatory disorder. It is therefore important to consider both primary and secondary causes when assessing hypogammaglobulinemia. This article will review these common causes and discuss an approach to assessment and management of SHG.

Understanding and Managing Adenotonsillar Hypertrophy in Pediatric Otolaryngology

Ivry Zagury-Orly, MD, MMSc, Jonathan MacLean, MD — Mon, 23 Sep 2024 00:00:00 +0000

Adenotonsillar hypertrophy (ATH) is a common pediatric condition marked by the growth of lymphoid tissues within the Waldeyer’s ring, which includes adenoids, palatine tonsils, and lingual tonsils. These tissues surround the upper airway and food passage, and play an immunological role, enlarging until about age 12, before gradually reducing during adolescence and adulthood.

Untreated or poorly managed ATH can severely impact multiple health aspects of children. It is the primary cause of upper airway obstruction and obstructive sleep apnea (OSA) syndrome in children, which disrupts sleep and can severely impair cognitive development, school performance and behaviour. Chronic mouth breathing from ATH can alter dental arches and facial growth, known as adenoid facies. More severe outcomes include increased pulmonary pressures and the potential development of pulmonary hypertension and cor pulmonale due to chronic hypoxia and CO₂ retention.

As a result, tonsillectomy, with or without adenoidectomy (T&A), has become one of the most frequently performed surgeries in North America, with over 530,000 operations performed annually on children under age 15. This paper discusses the significant impact of ATH on pediatric health and the frequent need for surgical intervention. It covers the immunophysiology, influence of atopy, community-based assessments prior to specialist referrals, and an overview of available medical and surgical treatment options. Additionally, it outlines general indications for referring patients to otolaryngology.

Abstract Presentation Highlights from the 2024 EAACI Annual Meeting

Susan Waserman, MSc, MDCM, FRCPC, Jason Ohayon, MD, FRCPC, Paul Keith, MD — Mon, 23 Sep 2024 00:00:00 +0000

Many oral abstracts, posters and case reports were presented at The European Academy of Allergy and Clinical Immunology (EAACI) Annual Meeting which was held in June 2024 in Valencia, Spain. We have selected the following 13 articles due to their relevance to Canadian allergy and immunology clinical practice and research.

Allergen Immunotherapy and Atopic Dermatitis: Updated Guidance

Derek K. Chu, MD — Mon, 23 Sep 2024 00:00:00 +0000

Atopic dermatitis (AD), also commonly referred to as atopic eczema, is the most common chronic inflammatory skin disease. Research over the past 30 years has revealed that it affects approximately 13% of children and 7% of adults worldwide. Among the growing number of treatment options for AD, the role of allergy to aeroallergens, such as house dust mite (HDM) pollens or animal dander, in driving this condition has remained uncertain for a long time. Consequently, so too has been the therapeutic role of allergen immunotherapy (AIT) for AD. The American Academy of Allergy, Asthma & Immunology (AAAAI)/American College of Allergy, Asthma and Immunology (ACAAI) Joint Task Force (JTF) on Practice Parameters recently updated their AD guidelines. This update included a systematic review of the effectiveness and safety of AIT, including subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) versus no AIT for patients with AD. This article summarizes the systematic review findings, guideline update, and future directions.

Pollen Cross-Reactivity: A Primer for Allergy Specialists

Tricia Sowers, PhD — Mon, 23 Sep 2024 00:00:00 +0000

There are over 400,000 land-based plant species that comprise our biodiverse habitat. Only a small subset of those plant species satisfies Thommen’s postulates, classifying them as allergens. The number of allergenic species, however, remains so vast that it is prohibitive to both test and treat for all relevant species within a geographical region. Allergy specialists have a valuable tool that can be used to help simplify the management of allergic patients: cross-reactivity.

Cross-reactivity is the ability for an allergen to induce an IgE-mediated response, regardless of previous exposure. Allergens are a complex milieu of proteins, some of which have allergic potential while others do not. A number of proteins are conserved across allergen species. When exposure to these conserved proteins occurs, the immune system recognizes them in a similar manner. For homologous or cross-reactive allergenic proteins, this conserved molecular recognition initiates the allergic cascade. Allergen characterization is critical to the understanding of cross-reactivity. Characterization, in this context, refers to the protein make-up of a particular allergen. The process of allergen characterization began in 1962 with the discovery of antigen E, the first identified allergenic protein. Antigen E, commonly known as Amb a 1, is an allergenic protein in ragweed, and is the primary sensitizing protein for ragweed allergy sufferers. These primary sensitizers are referred to as major allergens and can be defined as such when >50% of the allergic patient population is sensitized to them. An entire branch of research arose from this discovery, which has allowed for major advances to be made in the understanding of cross‑reactive relationships among allergen species. Cross‑reactivity is not limited to homologous major allergen expression. Rather, minor allergens and panallergens, though less clinically relevant, play a similar role in cross‑reactive relationships. This primer will explore the science behind cross‑reactivity, as well as provide a general overview of the cross‑reactive relationships that have been defined for plant allergens found across North America.