heterologous antiserum

het·er·ol·o·gous an·ti·se·rum

an antiserum that reacts with (for example, agglutinates) certain microorganisms or other complexes of antigens, even though the antiserum was produced by means of stimulation with a different microorganism or antigenic material or antiserum derived from another animal species.
See also: homologous antiserum.