Administering antibodies for temporary immune protection against an antigen. Immunity exists as long as the antibodies remain in the body, usually days or weeks.

involves the injection of immune mediators obtained by immunization of other subjects, into tumor-bearing hosts; prior to the development of monoclonal antibodies, most attempts at passive immunization have involved injection of heterologous serum.

immunization with preformed antibodies or antitoxins. Results in temporary immunity.