Structure and Function of Allergens 2022

Question 1

1. A 2-month-old infant boy was exclusively breastfed and then introduced a cow milk-based formula. An hour after feeding, he developed hives and tachypnea. In this case, which is the best the alternative to breast milk?
A. Goat milk
B. Mare milk
C. Sheep milk
D. Soy milk

Answer 1

1. D, Soy milk, p. 408.
   There is a high degree of cross-reactivity between cow milk with sheep and goat milk proteins, and several minor allergens have been identified (eg, serum albumin, immunoglobulin, and transferrin). While only 1 child out of 25 (4%) with IgE mediated cow milk allergy react to mare’s milk, the best alternative would be soy milk.

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 2

2. A 15-year-old teenage boy has mild persistent asthma and rhinitis due to dust mites. He develops a severe allergic reaction after consuming takeout shrimp fried rice.
   Which is the cross-reactive allergen shared between the two dissimilar species?
   A. Aldolase
   B. Arvalbumin
   C. Serum albumin
   D. Tropomyosin

Answer 2

2. D, Tropomyosin, p. 411.
   Cross-reactivity can occur between dissimilar species when proteins play a related physiologic role, such as the tropomyosins in arthropods (mites, snails, cockroaches, and crustaceans) and mollusks.

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 3

3. A 13-year-old teenage girl was gardening around flowering plants without gloves when she realized that she was stung by an insect.
   In this environment, what is the most likely major allergen?
   A. Antigen 5
   B. Phospholipase A1
   C. Phospholipase A2
   D. Procalin

Answer 3

3. C, Phospholipase A2, p. 415.
Phospholipase A2 (PLA2) is the major allergen in honeybee venom. 

Antigen 5 is the common name for the major allergen in the vespid venoms (eg, Ves v 5); phospholipase A1 (PLA1) is a minor vespid venom allergen. Procalin is an allergen found in the kissing bug (Triatoma protracta).

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 4

4. A major allergen from clinically important fungal species in respiratory diseases include:
A. Cla h 1.
B. Cop c 2.
C. Psi c 1.
D. Tri r 4.

Answer 4

4. A, Cla h 1, p. 401.
   Clinically important fungi include Aspergillus, Penicillium, Cladosporium, and Alternaria species, with allergens that may be cell wall– or cytoplasm-derived. Many are involved in protein
   synthesis or energy metabolism, although secretory allergens (eg, proteases) may also be involved. The major allergens from clinically important species in respiratory disease include Alt a 1, 2, and 13; Asp f 1, 2, and 4; and Cla h 1.

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 5

5. The predominant allergen in cat is:
A. Can f 1.
B. Bos d 2.
C. Fel d 1.
D. Fel d 2.

Answer 5

5. C, Fel d 1, p. 403.
   The predominant allergen in cat is Fel d 1, a heterodimeric protein. Fel d 1 comprises two distinct disulfide-bonded peptides, designated chains 1 and 2, and chain 1 shows sequence
   similarity with anti-inflammatory uteroglobins.

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 6

6. House dust mite is ubiquitous, with the most common species Dermatophagoides pteronyssinus and D. farina.
   What type of environment are these two species found in?
   A. Arid climates
   B. Subtropical climates
   C. Temperate climates
   D. Tropical climates

Answer 6

6. C, Temperate climates, p. 406.
   House dust mites (HDMs) are ubiquitous, but the most clinically important species belong to the Pyroglyphidae, Acaridae, Glycyphagidae, and Echimyopodidae families. They include Dermatophagoides pteronyssinus, D. farinae, and Euroglyphus maynei found in temperate climates; Blomia tropicalis, found in subtropical and tropical climates; and the storage mites such as Lepidoglyphus destructor, Tyrophagus putrescentiae, Acarus
   siro, and Glycyphagus domesticus that infest stored foods such as grains.

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 7

7. A 40-year-old male baker has suddenly developed asthma. He has never had any issues before and is curious if something in his environment may be contributing to his symptoms.
What is the occupational sensitizer?
A. Hydrolytic enzymes
B. Profilin
C. Persulfate
D. Conalbumin

Answer 7

7. A, Hydrolytic enzymes, p. 406.
   The main allergens for baker’s asthma include various hydrolytic enzymes, egg powder, latex products, and flours derived from various seeds.

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 8

8. A healthcare worker develops pruritus and tingling in the mouth after eating guacamole salsa.
   What is the most likely allergen causing his symptoms?
   A. Chitinases (Hev b 6)
   B. Endo-1,3 β-glucosidases (Hev b 2)
   C. Pathogenesis-related protein PR-10 (Bet v 1)
   D. Profilin (grass group 12)

Answer 8

8. B, Endo-1,3 β-glucosidases (Hev b 2), p. 406.

Allergy to proteins present in natural rubber latex from the lactiferous rubber tree (Hevea brasiliensis) arises through airborne, percutaneous, or parenteral routes and is prevalent
among individuals in frequent contact with natural rubber latex materials (eg, gloves and surgical materials). The allergens associated with latex–fruit allergies are endo-1,3 βglucosidases, patatin-like proteins, profilins, and nonspecific lipid transfer proteins.
The cross-sensitizing allergens shared between latex and foods such as
• Avocado
• Potato
• Banana
• Tomato
• Chestnut
• Kiwifruit
• Herbs
• Carrot
are
• Endo-1,3 beta glucosidase (Hev b 2)
• Patatin-like proteins (Hev b 7)
• Profilins (Hev b 8)
• Nonspecific lipid transfer proteins type 1 (Hev b 12).

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 9

9. How is pollination from angiosperms achieved?
   A. The Group 1 allergens involved in the cell wall loosening process enables pollen tube growth.
   B. Pollen constituents either diffuse out or are expelled from the grains onto the stigma surface, after which the pollen tube emerges and grows toward the ovum.
   C. Pollen is either trapped by a pollination drop that emanates from the exposed ovula or are engulfed by the ovula extensions.
   D. Microsporocytes give rise to pollen grains by meiosis

Answer 9

9. B, Pollen constituents either diffuse out or are expelled from the grains onto the stigma surface, after which the pollen tube emerges and grows toward the ovum, p. 392-3.
   The pollination of angiosperms is described as pollen constituents either diffuse out or are expelled from the grains onto the stigma surface, after which the pollen tube emerges and
   grows toward the ovum.

Answer option A describes pollination of grass pollens. Answer option C describes pollination of gymnosperms. Answer option D describes pollination of a specific type of gymnosperms called conifers.

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition

Question 10

10. A 55-year-old man develops urticaria 7 hours after eating steak. You suspect an allergic reaction to an arthropod may be the cause of his outbreak.
    What arthropod is he likely sensitized to?
    A. Aedes aegypti
    B. Amblyomma americanum
    C. Argasidae reflexus
    D. Triatoma protracta

Answer 10

10. B, Amblyomma americanum, p. 408.
    For the red meat–associated alpha gal epitope, the sensitizing allergen is not red meat, but rather exposure to the tick Amblyomma americanum.

Chapter 26: The Structure and Function of Allergens
Middleton’s Allergy Principles and Practice, 9th Edition