Which is the Most Efficient at Initiating the Classical Pathway

Question

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

Accepted Answer

IgM is the most efficient at initiating the classical pathway of the complement cascade because it has 10 binding sites and can activate many C1 molecules, leading to a strong complement activation response. Other immunoglobulins (IgA, IgD, and IgE) have fewer binding sites and are therefore less efficient at initiating the classical pathway.