FLUORESCENT, ELECTRON MICROSCOPIC, AND IMMUNOELECTROPHORETIC STUDIES OF LABELED ANTIBODIES.

Antibodies, produced in rabbits, to each of three bacterial species have been doubly labeled with fluorescein and ferritin. Irrespective of which label was conjugated to the antibody first, immunologic activity was maintained. Moreover, these preparations gave as high a degree of specificity in fluorescent and electron microscopic studies as did singly labeled antibodies. Immunoelectrophoretic analyses and other immunologic tests further confirmed that the antibodies were conjugated to both labels without loss of specific activity. The technique thus permits the relatively simple method of immunofluorescence to be used as an aid in selecting optimtum ferritin antibody conjugates for localizing of antigen at the molecular level by means of electron microscopy.