Class switching of activated B cells typically converts which immunoglobulin?

Class switching in B cells refers to the process by which a B cell changes the class of antibody it produces while retaining the same antigen specificity. This occurs after the B cell has been activated by an antigen and signals from T helper cells.

The most common example of class switching is the conversion of immunoglobulin M (IgM) to immunoglobulin G (IgG). IgM is typically the first antibody produced in response to an infection, providing an initial defense against pathogens. However, IgG provides a more effective and versatile immune response, including opsonization, neutralization, and activation of the complement system.

During class switching, the constant region of the antibody molecule is altered, allowing the B cell to produce a different class of immunoglobulin that can better handle the immune challenges. The ability to switch to IgG from IgM represents an evolutionarily advantageous mechanism, enhancing the immune system’s response to infections.

The other potential immunoglobulin conversions listed in the options do not typically represent the primary role of class switching in response to antigens. Each immunoglobulin class serves different functions, but the transition from IgM to IgG is a foundational aspect of adaptive immunity, making the correct response clear.