Opportunistic infections are a major cause of morbidity and mortality in AIDS patients. Although it is generally believed that the early diagnosis and treatment of an opportunistic infection is critical to decreasing morbidity and increasing overall survival, localizing the site of these infections is often difficult. Currently, there are two accepted techniques for whole-body evaluation using radionuclides: 111 In-oxine-labeled autologous white blood cell (WBC) scintigraphy and 67Ga citrate scintigraphy. The objective of the proposed project is to test the use of a 99mTc-labeled, monoclonal antibody-based imaging reagent for detecting hidden infections in patients with AIDS. The antibody binds to the surfaces of human neutrophils, thus permitting in vivo tagging of the cells most likely to be found at the site of an abscess or infection. The investigator expects that the use of the 99mTc-labeled antibody will improve the timeliness and accuracy of diagnosis and will eliminate the risks associated with the use of ex vivo- labeled, 111 In white blood cells.