Which class of antibodies primarily stabilizes during the plateau phase of a primary immune response?

During the plateau phase of a primary immune response, IgM is the class of antibodies that primarily stabilizes. The primary immune response typically involves a lag phase where the immune system recognizes an antigen, followed by a brisk ramp-up in antibody production, primarily of IgM. This phase represents the body’s initial reaction to a new infection.

As the response progresses, IgM levels reach a peak and then stabilize during the plateau phase. IgM is usually the first antibody produced in response to an infection. It is efficient in neutralizing pathogens and activating the complement system, playing a crucial role during the early stages of an immune response.

While IgG is a dominant antibody during the later stages of the immune response and after class switching occurs, it does not stabilize during the plateau of the primary immune response but rather increases following the initial IgM response. IgA primarily functions in mucosal immunity, while IgE is mainly involved in allergic reactions and responses to parasitic infections. Thus, the focus on IgM during the plateau phase highlights its critical role as the first responder in the antibody-mediated immune response.