Antibody-dependent cytotoxicity 

Mechanism: Either IgG or IgM is made against  antigens. The binding of these antibodies to the surface of host cells then leads to:

1. opsonization  of cells whereby phagocytes (macrophages/neutrophils) stick to host cells by way of IgG,  and discharge their lysosomes 

2. activation of the classical complement pathway causing  lysis  of the cells

3. ADCC  destructionof the cells whereby NK cells  attach to the Fc portion  of the antibodies. The NK cell then release pore-forming proteins called perforins and proteolytic enzymes called granzymes. Granzymes pass through the pores and activate the enzymes that lead to apoptosis of the infected cell by means of destruction of its structural cytoskeleton proteins and by chromosomal degradation.