[07.31] Food Allergy and Intolerance V2.2.pdf

Food Allergy

What is defined as an adverse health effect arising from a specific immune response that occurs reproducibly on an exposure to a given food?

Sensitization and specific signs/symptoms

A food allergy diagnosis requires the presence of which two factors?

Food Allergens

What are the specific components of food or ingredients recognized by immune cells that elicit immunologic reactions?

Proteins

While some are chemical haptens, food allergens are typically what type of macromolecule?

Physiologic and Immunologic

The gastrointestinal mucosal barrier is composed of which two general components?

Single layer of epithelial cells

What constitutes the primary cellular component of the physiologic GI barrier?

Tight junctions

What structures join the epithelial cells of the GI tract together?

Thick mucus layer

What physiologic component traps particles, bacteria, and viruses in the gut?

Innate and Adaptive

The immunologic component of the GI barrier is divided into which two systems?

Macrophages, NK cells, Epithelial cells, and Toll-like receptors

Name four components of the innate immune system in the GI tract.

Lymphocytes, Peyer's patches, secretory IgA (sIgA), and cytokines

Name four components of the adaptive immune system in the GI tract.

4 years old

The sIgA system is not fully mature until a child reaches what age?

Suboptimal enzyme activity

Why is the mucosal barrier efficiency not optimal in the newborn period?

Decreased gastric acidity (Antacids)

What medication-induced change can promote sensitization by increasing exposure to intact proteins?

Oral Tolerance

What is the normal state of the intestine where it develops a lack of response to harmless exogenous antigens?

Small intestine

Where in the gastrointestinal tract does the greatest antigenic burden from food occur?

Colon

Where in the gastrointestinal tract does the greatest antigenic burden from microbiota occur?

T-regulatory cells (Treg)

Which cells are considered the most important for the immune regulation of oral tolerance?

IL-10 and TGF-Beta

Which two cytokines are key for immune regulation in the gut?

sIgA (Secretory IgA)

Which antibody binds food proteins to prevent antigenic absorption through the intestinal epithelium?

TGF-Beta

The production of antigen-specific IgA, linked to tolerance, is induced by which cytokine?

Antimicrobial peptides

What substances are secreted by epithelial cells into the mucosa to provide a barrier function?

GALT (Gut-associated lymphoid tissue)

What extensive immune organ must distinguish non-pathogenic from pathogenic organisms in the gut?

Increased permeability

What characteristic of the neonatal intestinal barrier impacts tolerance development due to increased antigenic load?

2%

Approximately what percentage of ingested food antigens are absorbed in an immunologically intact form even in a mature gut?

Deletion of effector T-cells

In mice models, what occurs during "high dose" oral tolerance?

Activation of regulatory T-cells

In mice models, what occurs during "low dose" oral tolerance?

Commensal gut flora

Mice raised in a germ-free environment lack normal tolerance, proving the importance of what?

TH2 response

Genetically predisposed individuals respond to allergenic proteins with what specific type of allergic response?

B-cells

Which cells produce specific IgE antibodies?

Mast cells and basophils

IgE antibodies bind to high-affinity receptors on which two types of cells?

Crosslinking

Degranulation occurs when specific proteins cause what to happen to IgE on the surface of mast cells?

Histamine

What is a primary mediator released during the degranulation of mast cells in an IgE-mediated allergy?

T-cells

Non-IgE mediated allergic reactions are primarily driven by mediators released from which cells?

Vascular leakage and inflammation

Non-IgE mediated reactions are characterized by which two physical processes?

Egg, milk, peanut, tree nuts, fish, shellfish, wheat, and soy

Name the eight most significant food allergies worldwide.

Water-soluble glycoproteins

What are the three common biochemical features of major food allergens?

10 to 70 kDa

What is the typical size range of major food allergens?

Stable to heat, acid, and proteases

Why are major food allergens not easily broken down during digestion?

Roasting

In westernized countries, which peanut preparation method increases protein stability and allergenicity?

Boiling or frying

In Asia, peanuts are primarily prepared in which two ways, resulting in lower allergenicity?

Emulsification (Peanut butter)

Which food preparation method increases allergenicity through an "adjuvant effect"?

Baked forms

70-80% of children allergic to milk or egg can tolerate them in what specific form?

Denaturing the proteins

Why does high-heat baking often make eggs or milk tolerable for allergic children?

1% to 10%

Food allergy is estimated to affect what percentage of the general population?

Self-reported

Which is more common: proved (tested) food allergy or self-reported food allergy?

12-13%

What is the estimated prevalence of self-reported food allergy?

3%

What is the prevalence of proved food allergy based on oral food challenges?

Children

Is food allergy more common in children or adults?

Atopic dermatitis (AD)

Children with a moderate-to-severe form of which condition have a 35% risk of food allergy?

Hygiene hypothesis

Which hypothesis is proposed as a reason for the increasing prevalence of food allergies?

Vitamin D

Insufficiency of which vitamin is a modifiable risk factor for food allergy?

Topical exposure

Using peanut oil as a moisturizer is an example of what type of exposure that increases allergic risk?

Delayed introduction

Contrary to old beliefs, what practice regarding "allergenic" foods has actually resulted in more allergies?

Age 16

While childhood allergies were once thought to resolve by age 3, 80% of milk/egg allergies actually resolve by what age?

20%

What percentage of peanut allergies in young children resolve by school age?

Recurrence

What has been described in children who outgrew a peanut allergy but did not maintain continued exposure?

10%

By age 4, what percentage of tree nut allergies resolve?

Pathophysiology of the allergy

Rate of allergy resolution varies by food, patient age, and what other factor?

Modifiable risk factors

Skin barrier dysfunction and maternal dietary habits are examples of what kind of risk factors?

Non-modifiable risk factors

Gender, racial background, and family history are examples of what kind of risk factors?

IgE-mediated

Food-induced allergic disorders with an acute onset are typically which category?

Non-IgE-mediated (or Cell-mediated)

Food hypersensitivity disorders that are subacute or chronic are usually which category?

Anaphylaxis

What is the quintessential IgE-mediated food reaction?

Oral Allergy Syndrome (OAS)

Which IgE-mediated condition involves pruritus and mild edema confined to the oral cavity?

Cutaneous manifestations (e.g., Urticaria)

Non-IgE-mediated reactions generally show GI reactions instead of what?

Protein-induced enterocolitis

Name a specific non-IgE-mediated adverse food reaction.

Food Intolerances

Non-immunologic food reactions are commonly called what?

Toxic/Pharmacological Reactions

Which category of food reaction does not depend on the host and can be elicited in anyone?

Scombroid fish poisoning

Which toxic reaction involves histamine release from tainted fish, causing itching?

Caffeine and Alcohol

Name two common substances that cause pharmacological non-immunologic reactions.

Lactose Intolerance

What is the most common host-specific metabolic disorder caused by disaccharidase deficiency?

Psychiatric disorder

Under what category of non-toxic intolerant reactions is Anorexia Nervosa classified?

Acute

Does food commonly cause acute or chronic urticaria?

Direct skin contact

Contact urticaria occurs through what mechanism rather than ingestion?

Pollen

Oral Allergy Syndrome is often related to a cross-reactivity with what environmental allergen?

Labile

Pollen proteins share homologous antigens with which type of food proteins that are easily denatured by heat?

Birch pollen and Apple

Name a specific pollen-food pair mentioned in the context of Oral Allergy Syndrome.

Aerosolized food protein

Allergic rhinitis or asthma can be triggered by the inhalation of what?

Food-Associated, Exercise-Induced Anaphylaxis

What condition requires both the ingestion of a specific food and physical activity to trigger a reaction?

Exercise

What factor is presumed to alter gut absorption or allergen digestion in exercise-induced anaphylaxis?

Cardiovascular collapse

Anaphylaxis is a multiple organ system reaction that can include what fatal complication?

Platelet-activating factor

Aside from histamine and tryptase, what mediator plays a key role in anaphylaxis?

35%

What percentage of children with moderate-to-severe atopic dermatitis have a food allergy?

Eosinophils

Eosinophilic gastroenteropathies are caused by the infiltration of which cells into the tissue?

Dysphagia and food impaction

How does Eosinophilic Esophagitis typically present in adolescents and adults?

Esophagus

Which part of the GI tract is normally devoid of eosinophils, making a biopsy easy to interpret?

Tissue biopsy

What is required to confirm the presence of eosinophils for a clinical pathologic diagnosis of EE?

FPIES (Food Protein-Induced Enterocolitis Syndrome)

Which serious non-IgE disorder manifests in infants as repetitive projectile emesis, dehydration, and hypotension?

Shock

FPIES is considered an emergency in young children because dehydration can quickly lead to what?

2-4 hours

In FPIES, a subacute syndrome typically occurs how long after re-exposure to the offending food?

TNF-alpha

FPIES is associated with an increased response of which cytokine?

Dietary Protein Proctitis

Which infant condition presents as mucus-laden, bloody stools in an otherwise healthy baby?

Milk protein

Which food is most commonly implicated in Dietary Protein Proctitis?

20%

What percentage of adults and children alter their diet for a "perceived" allergy when they are actually not allergic?

Tyramine

Which pharmacological component in aged cheeses can trigger migraines?

Auriculotemporal syndrome

Which neurologic response is manifested by a facial flush after eating tart foods?

Gustatory rhinitis

What is the term for rhinorrhea triggered by hot or spicy foods?

Migraines, Arthritis, and Seizures

Name three disorders not proven to be related to food allergy despite popular belief.

Is there a pattern?

What is a key question during history taking to determine if a reaction is truly food-related?