Neutralisation.

Antibodies bind to toxins produced by pathogens making them harmless.Pathogens that invade the host cell using host-cell receptors are unable to do so if their attachment proteins are bound or if they are part of an antibody-antigen complex.

Opsonisation

Antibodies act as opsonins so the antibody-antigen complex is more easily engulfed by the phagocyte. Without opsonisation the phagocyte relies on a much less frequent chance encounter with the pathogen. Opsonisation speeds up the clearance of pathogens.

Agglutination

Antibodies act as agglutinins, clumping the pathogens together, preventing their spreading and allowing more than one pathogen to be engulfed at one time.