What is the process called when a patient's IgM alloantibodies change to IgG alloantibodies?

The process in which a patient's IgM alloantibodies change to IgG alloantibodies is known as isotype switching. This is a critical mechanism in the adaptive immune response that allows B cells to produce different classes of antibodies (isotypes) with distinct functions while maintaining the specificity for the same antigen.

During isotype switching, activated B cells undergo a genetic rearrangement that changes the constant region of the antibody heavy chain. Initially, B cells typically produce IgM antibodies. Upon activation and under the influence of various cytokines, B cells can switch to produce IgG, which is often more effective in opsonization, neutralization, and activating complement compared to IgM. This transition enhances the immune response and allows for a more targeted and adaptive reaction against pathogens.

Understanding isotype switching is essential, particularly in the context of immunological compatibility and transplant medicine, where the generation of IgG antibodies against donor antigens can lead to rejection. The ability to recognize this process provides insights into the dynamics of the immune response and its implications for patient management.