What is the primary role of IgD immunoglobulin?

The primary role of IgD immunoglobulin is indeed associated with the differentiation of B-lymphocytes. IgD is primarily found on the surface of immature B cells, where it plays a key role in the process of B cell activation. Once a B cell encounters an antigen, IgD helps signal the cell to differentiate into plasma cells, which then produce antibodies, or mature B cells that can further enhance the immune response.

This function is crucial for the development and maturation of the immune response, as it enables B cells to recognize and create specific antibodies against pathogens. Understanding the role of IgD in B-lymphocyte differentiation is essential for grasping how the adaptive immune system operates and responds to infections or vaccines.

In contrast, the other roles mentioned are more closely associated with different immunoglobulins. For instance, manifestations of allergic reactions are primarily mediated by IgE, whereas the protection of mucous surfaces is largely the function of IgA. The primary immune response is mainly attributed to IgM, which is produced first in response to an infection. Thus, the unique role of IgD in B cell differentiation highlights its importance in the immune system's functionality.