American Board of Surgery Qualifying Exam (ABS QE) Practice Test

When is IgG typically produced during an infection?

1. At the onset of infection

2. Immediately after IgM

3. During chronic infections

4. After the primary infection has passed

The correct answer is: After the primary infection has passed

IgG is typically produced during the later stages of an infection. When the body encounters an antigen, the immune system first generates IgM antibodies as part of the initial immune response. These IgM antibodies are formed quickly, usually peaking within a few days after the onset of the infection. As the immune response matures, typically days to weeks later, IgG antibodies are produced in greater quantities. This transition from IgM to IgG is crucial for establishing long-lasting immunity and providing protection against future infections by the same pathogen. IgG has a longer half-life and provides more sustained protection compared to IgM. Therefore, significant IgG production occurs after the primary infection has peaked and is often instrumental in the recovery phase, marking its role in both the ongoing response to the pathogen and the formation of immunological memory. While it is possible for IgG production to occur in chronic infections as well, its primary characteristic is that it reflects the tail end of the acute phase of the primary infection, emphasizing its association with immune memory rather than serving as the body's first response.