What maternal immunological marker is elevated in rubella diagnosis?

In the context of rubella diagnosis, the elevation of IgM is a key immunological marker. When a mother is infected with the rubella virus, her immune system responds by producing specific antibodies to combat the infection. IgM antibodies are the first class of antibodies produced in response to a new infection and indicate recent exposure.

The presence of IgM in the serum is particularly important because it is not typically found in the absence of an active infection, making it a reliable indicator of acute infection. Therefore, measuring the levels of IgM can help confirm a diagnosis of rubella during pregnancy, which is crucial given the potential teratogenic effects of the virus on the developing fetus.

While IgG is associated with past infections and long-term immunity, and IgA and IgE serve different roles in the immune response (with IgA primarily involved in mucosal immunity and IgE associated with allergic responses), they are not specific markers for recent rubella infection. Thus, the elevation of IgM is the correct and indicative response to rubella diagnosis.