Immunology Quiz#12 : Complement System

1. A 4-year-old boy presents with recurrent Neisseria meningitidis infections. Laboratory analysis reveals a deficiency in a serum protein that plays a critical role in the formation of the membrane attack complex (MAC). Which of the following complement components is most likely deficient in this patient? 

Question 1 of 5

2. A 30-year-old woman with systemic lupus erythematosus (SLE) is noted to have low levels of certain complement proteins. The decrease in these proteins is most likely due to their consumption in immune complex formation and deposition. Which of the following complement proteins is typically decreased in serum during active SLE due to consumption? 

Question 2 of 5

3. During a study session, a group of medical students discusses the role of complement in defending against bacterial infections. One student mentions that a specific complement activation pathway is initiated by antibodies bound to the pathogen surface. Which of the following pathways is initiated in this manner? 

Question 3 of 5

4. A new experimental drug is designed to inhibit the activation of the complement system at an early stage. This drug specifically targets a protein that acts as a key enzyme in the cleavage of both C3 and C5. Inhibition of which of the following proteins would most likely achieve this effect? 

Question 4 of 5

5. A pediatrician evaluates a 2-year-old child with recurrent pyogenic infections and notes that the child has a deficiency in a complement component that is critical for opsonization. Which of the following complement components is most likely deficient in this child, given the role of opsonization in enhancing phagocytosis? 

Question 5 of 5


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