Ace the Certified in Public Health (CPH) Exam 2025 – Launch Your Health Hero Journey!

Immunoglobulin G (IgG) plays a key role in the immune system and is primarily associated with passive immunity. This type of immunity occurs when antibodies from one individual are transferred to another individual, providing immediate protection without the recipient's immune system actively producing those antibodies.

In the case of IgG, it can be transferred from mother to child through the placenta during pregnancy or through breast milk after birth, offering the newborn immediate, albeit temporary, protection against various pathogens until the child’s immune system becomes fully functional. This transfer helps protect infants during their early life when their own immune responses are still developing.

Active immunity, on the other hand, involves the body actively responding to an infection or vaccination by producing its own antibodies, which is not the case with IgG when it is provided through passive means. Innate immunity refers to the first line of defense against pathogens that are not specific to particular infections, while cell-mediated immunity typically involves T cells and is a different mechanism than that involving antibodies like IgG. Understanding these distinctions clarifies why IgG is classified under passive immunity.