Final answer:
ADCC is an immune response that targets large pathogens coated with antibodies, using effector cells like NK cells to kill them. The most effective targets of ADCC are eukaryotic pathogens, which are large enough to require cell-mediated cytotoxicity.
Step-by-step explanation:
Antibody-dependent cell-mediated cytotoxicity (ADCC) is a critical immune response where effector cells such as natural killer (NK) cells, macrophages, and eosinophils destroy large pathogens that are coated with antibodies, particularly IgG. The Fab region of an antibody binds to the pathogen, while the Fc region is recognized by Fc receptors on effector cells, bringing them close to the pathogen. The effector cells then release cytotoxins like perforin and granzymes to kill the pathogen.
Based on this mechanism, ADCC is most effective in destroying eukaryotic pathogens which are typically larger and not effectively neutralized by antibody coating alone. It does not primarily target bacterial toxins, prions or external viruses, as these are not as effectively dealt with by ADCC. Hence, ADCC enhances the immune system's ability to tackle large, multicellular pathogens or infected cells that require cell-mediated destruction.