Final answer:
No, the specificity of B cell clones does not change during isotype switching as the variable region of the antibody, which determines specificity, remains unchanged while only the constant region, determining the class of antibody, is altered.
Step-by-step explanation:
The specificity of B cell clones does not change during isotype switching. Isotype switching is a process where B cells switch from producing one type of antibody (such as IgM) to another (such as IgG, IgA, or IgE) without altering their specificity for the antigen's epitope. This means that even though the constant region of the antibody undergoes genetic rearrangement, the variable region, which is responsible for binding to a specific antigen, remains the same. Therefore, plasma cells cloned from the same activated B cell can produce a variety of antibody classes that have the same epitope specificity.
The variety in the variable regions of antibodies is generated earlier in B cell development, when DNA recombinase catalyzes the random excision of V and J segments from the light chain gene. This process, along with splicing at the mRNA level, ensures that each antibody has a unique variable region capable of binding a different antigen. Thus, when considering isotype switching, the answer is b) No, the specificity does not change.