Why the immune system to be able to respond with different classes of antibodies to different pathog

There are five different classes of immunoglobulins (IgG, IgM, IgA, IgD, and IgE) based on their functions, chemical structure, biological features, distribution, and target specificity.

For example, only IgG and IgM antibodies can activate complement pathways. Immunoglobulin M (IgM) is the first antibody that interacts with new bacteria that enters the body, and it initiates a primary immune response. IgA antibodies protect the body from bacterial growth and colonization. However, it is less stable than IgG and can be found in a lower quantity, accounting for about 10-15% of the total immunoglobulins in the blood. IgD regulates the B-cells’ activation and differentiation into plasma cells.

The take-home message here is that each one performs a certain task, hence we need different types of succeed against an attack.