Which class of immunoglobulin is found in higher concentrations in blood serum?

The class of immunoglobulin that is found in higher concentrations in blood serum is IgG. This is because IgG is the most abundant type of antibody in circulation, making up approximately 70-75% of the total immunoglobulin pool in serum. Its primary role is to provide long-term immunity and it is pivotal in the body's immune response to pathogens. IgG can effectively neutralize toxins and viruses, opsonize pathogens for phagocytosis, and activate complement pathways, all of which contribute to its prominence in serum.

In contrast, IgA is mainly found in mucosal areas, such as the gut and respiratory tract, and in secretions like saliva and breast milk, rather than in the bloodstream. IgD is found in very low concentrations in serum and is primarily associated with B cell maturation and activation. IgE is also present in minimal concentrations in blood and is primarily involved in allergic reactions and responses to parasitic infections. Therefore, while all these immunoglobulins play important roles in the immune system, IgG's higher concentration in blood serum distinguishes it as the primary antibody in circulation.