In passive immunity, antibodies are developed in the laboratory that are specific to some particular pathogen. And these antibodies, when they're injected into our body they begin to circulate in our blood system, in our lymph system and in our tissue. And if we are exposed to that pathogen that carries that antigen that is complementary to the antibody that was injected into our body in the first place, those antibodies will bind onto those antigens. The artificial antibodies will bind onto the antigens and that will initiate a response in which it will label those antigens as well as the pathogen for destruction by our white blood cells. Now, one very important point about passive immunity, once again, is it does not develop memory cells. And so this means that eventually these antibodies will be degraded inside our body and they will cease to exist.