There are 5 different classes of antibody: IgG, IgM, IgD, IgE and IgA. What makes them different from one another is the amino acid sequences found in the Fc region of the heavy chain. Since effector function relies on the amino acid sequences in the Fc region, hence some of the functions they provide are class specific. In total, there are 4 main effector functions of antibodies: neutralization of microorganisms and toxins, antibody-mediated opsonisation and phagocytosis of microorganisms, antibody-dependent cell cytotoxicity and activation of complement pathway.
Neutralization of microorganisms is where the antibodies bind to the microorganisms, preventing it from interacting with the cell surface receptor. By binding to the microorganisms, it also prevent the spread of infection from cell to cell. Neutralization of toxins is completed by the antibodies blocking the toxins of microorganism by binding to the cell surface receptors. This then inactivate the harmful effects of the toxins. The same goes to virus neutralization where antibodies bind to the virus and block it from attaching to the host cell, which prevent it from replicating within the cell since virus are intracellular. This function is produce by IgG only and is Fab dependent instead of the Fc region.
The next effector function is the opsonisation and phagocytosis of bacteria. What happens here is that the antibodies, which in this case are IgG, will bind to the antigens of the microorganism. This make it more susceptible to ingestion by phagocytic cells like macrophages and dendritic cells. The antibodies-antigens complex, in another words, the opsonised microorganisms will then bind onto the Fc receptors of the phagocytic cell. Signal from the Fc receptors promote the phagocytosis of the opsonized microbe and can activate the phagocyte to kill the microbe.
As for antibody-dependent cell toxicity,natural killer cells use Fc receptors to bind to infected host cells and kill...