Exam 5: The Complement System

A common denominator among the three complement pathways is antigen recognition.Can you name three molecules that act as antigen recognition molecules for the classical, lectin, and alternative pathways?

Complement components can be classified into seven functional categories, including

Which of the following acts as a positive regulator of complement fixation via stabilization of C3bBb?

Which of the following is the first complement factor to be activated, resulting in insertion of one of its subunits into the pathogen surface in two of the three complement fixation pathways?

Complement is subject to rigorous regulatory mechanisms.C1INH can inhibit both the classical and lectin pathways.What function feature of C1INH allows for inhibition of both pathways?

In your own words, and using no more than two sentences, explain how DAF regulates complement to inhibit MAC-mediated lysis.

Which of the following can be directly activated as a soluble protein in the microenvironment surrounding a pathogenic cell?

Which of the following complement fixation pathways can be initiated by a soluble C3 convertase?

Which of the following binds to surface-bound C3b during formation of the alternative C3 convertase?

Name two complement proteins whose primary functions are promoting anaphylatoxin activity.What common structural feature of the two named proteins allows for their inactivation by way of serum carboxypeptidases?

How does binding of complement-opsonized microbes to CR1 facilitate clearing of the microbe from the host?

Which of the following is the MOST potent anaphylatoxin produced during the complement cascade?

Which of the following acts as a serine protease that, with cofactors, cleaves C3b and C4b?

Of the molecules listed, which can be considered the key molecule in complement pathways?

You suspect that you have identified a mouse line that lacks a functional complement system.A friend suggests collecting serum and looking for hemolytic activity as a first screen in determining complement activity in the line.Do you agree or disagree with your friend, and why?

Some strains of staphylococcal bacteria express staphylokinase.Staphylokinase can degrade IgG.Based on this information, how will staphylokinase disrupt complement? Which pathway is most impacted?

Which of the following provides serine protease activity in the classical complement activation pathway?

Which of the following immunoglobulin isotypes is the MOST efficient at initiating a complement fixation cascade?

Complement activation is implicated in the pathogenesis of SLE.However, the incidence of SLE is highly correlated to C4 deficiency.Can you explain this paradox?