How does IgG contribute to the immune response?

Immunoglobulin G (IgG) plays a multifaceted role in the immune response, contributing to the body's defense against pathogens through various mechanisms.

One key function of IgG is its ability to bind directly to pathogens, such as bacteria and viruses. This binding helps to neutralize the pathogen's ability to infect host cells and marks it for destruction by immune cells.

Additionally, IgG is effective in neutralizing toxins produced by certain pathogens. By binding to these toxins, IgG prevents them from interacting with cell receptors and exerting harmful effects on the body.

Furthermore, IgG can activate the complement system, a group of proteins that work together to enhance the ability of antibodies and phagocytic cells to clear microbes and damaged cells, promote inflammation, and attack the pathogen's cell membrane. This activation is crucial for amplifying the immune response and enhancing pathogen clearance.

Since IgG contributes to all these processes—binding to pathogens, neutralizing toxins, and activating the complement system—option D encapsulates the comprehensive role of IgG in the immune response effectively.