Which antibody provides the majority of antibody-based immunity against invading pathogens?

Which antibody provides the majority of antibody-based immunity against invading pathogens?

• A. IgA
• B. IgG
• C. IgM
• D. IgE

Answer: (B)

IgG is the main antibody type responsible for most antibody-based immunity in the body. It is the most abundant immunoglobulin in serum, making up the majority of circulating antibodies. This high quantity, combined with its high affinity from somatic hypermutation, allows IgG to effectively neutralize pathogens and toxins, and to opsonize microbes for efficient phagocytosis. It also activates the classical complement pathway, boosting pathogen clearance, and can mediate antibody-dependent cellular cytotoxicity. IgG persists long-term and is the key antibody produced during memory responses; it is even transferred across the placenta to provide fetal and newborn protection. In contrast, IgA mainly guards mucosal surfaces, IgM is produced early and has strong complement-activating capacity but lower affinity, and IgE is involved in defense against parasites and in allergic reactions but is present at much lower levels.

IgG is the main antibody type responsible for most antibody-based immunity in the body. It is the most abundant immunoglobulin in serum, making up the majority of circulating antibodies. This high quantity, combined with its high affinity from somatic hypermutation, allows IgG to effectively neutralize pathogens and toxins, and to opsonize microbes for efficient phagocytosis. It also activates the classical complement pathway, boosting pathogen clearance, and can mediate antibody-dependent cellular cytotoxicity. IgG persists long-term and is the key antibody produced during memory responses; it is even transferred across the placenta to provide fetal and newborn protection. In contrast, IgA mainly guards mucosal surfaces, IgM is produced early and has strong complement-activating capacity but lower affinity, and IgE is involved in defense against parasites and in allergic reactions but is present at much lower levels.