Section 866.5640 - Infectious mononucleosis immunological test system(a)Identification. An infectious mononucleosis immunological test system is a device that consists of the reagents used to measure by immunochemical techniques heterophile antibodies frequently associated with infectious mononucleosis in serum, plasma, and other body fluids. Measurements of these antibodies aid in the diagnosis of infectious mononucleosis.(b)Classification. Class II (performance standards).47 FR 50823, Nov. 9, 1982; 47 FR 56846, Dec. 21, 1982