Final answer:
The process where antigen-antibody complexes help NK cells to induce apoptosis in virally infected cells is known as antibody-dependent cell-mediated cytotoxicity (ADCC).
Step-by-step explanation:
When virally infected host cells are tagged by antigen-antibody complexes, natural killer (NK) cells are recruited, which subsequently induce apoptosis in the infected host cell. This immune response is known as antibody-dependent cell-mediated cytotoxicity (ADCC). In this process, the Fc region of an IgG antibody connects with Fc receptors on NK cells, which then release cytotoxins like perforin and granzymes to kill the pathogen.
Unlike mechanisms such as neutralization and opsonization which deal with extracellular pathogens, ADCC specifically targets cells that are infected by dealing with intracellular pathogens that antibodies cannot neutralize on their own since they cannot penetrate the cell membrane. ADCC complements the action of cytotoxic T cells which also induce apoptosis, but do so after recognizing specific antigens presented by infected cells.