Indium-111-Labeled Human Nonspecific Immunoglobulin G: A New Radiopharmaceutical for Imaging Infectious and Inflammatory Foci

Indium-111-labeled human nonspecific immunoglobulin G (111In-IgG) is a newly developed radiopharmaceutical for imaging infectious and inflammatory foci. This article presents an overview of the literature concerning In-IgG scintigraphy. The current theory about the mechanism of accumulation suggests that 111In-IgG accumulates in lesions as a result of enhanced vascular permeability and subsequent entrapment of the radiolabeled protein. Human studies show excellent results in imaging bone and joint, abdominal, and intravascular infection. Of special interest is the ability to depict infectious foci in granulocytopenic patients. The value of 111In-IgG scintigraphy for detection of infection is compared with that of gallium-67, labeled-leukocyte, and technetium-99m (99mTc) nanocolloid scintigraphy. The significance of differences between 111In-IgG scintigraphy and two other new scintigraphic techniques, 99mTc-labeled IgG and 99mTc-labeled murine monoclonal anti-granulocyte antibody BW 250/183, are discussed.