Which is the most efficient at initiating the classical pathway of the complement cascade?
A)IgA
B)IgD
C)IgM
D)IgE

Question

Quizplus · Accepted Answer

IgM is the most efficient at initiating the classical pathway of the complement cascade because it has ten binding sites for complement component C1q, which is required for the activation of the classical pathway. In contrast, IgG has only two binding sites for C1q. IgA, IgD, and IgE do not have binding sites for C1q, so they cannot initiate the classical pathway directly.

Which Is the Most Efficient at Initiating the Classical Pathway