Heterozygosity at Gm loci associated with humoral immunity to osteosarcoma.

Serum samples from 50 Caucasian patients with osteosarcoma were tested for the presence of antibodies to osteosarcoma-associated antigens (OSAA) and typed for nine Gm markers. A highly significant association was found between Gm 3;5,13,14 and unresponsiveness to OSAA, and between 1,3,17;5,13,14,21 and responsiveness to OSAA. These results suggest the existence of complementary immune response genes which in the heterozygous condition permit a response to OSAA.

Comparative study of monoclonal antibody scan in diagnosing orthopaedic infection.

When clinical data are insufficient to diagnose infection of bone or joints, nuclear scanning becomes crucial in making an accurate diagnosis. The efficacy of (99m)technetium antigranulocyte monoclonal antibody Fab' fragment (LeukoScan) is prospectively compared with (111)indium white blood cell and (99m)technetium methylene diphosphonate bone scans in 74 patients with suspected musculoskeletal infections. They were grouped according to site of suspected infection: 33 long bones, 23 prosthetic joints, and 18 diabetic feet. Sixty-two of these 74 patients had surgical verification with histopathology or culture. The remaining 12 patients had clinical followup as proof of absence of infection. The overall sensitivity of LeukoScan, (111)indium white blood cell, and (99m)technetium methylene diphosphonate bone scans was 93%, 85% and 92%, respectively. Specificity was 89%, 75% and 52%, and accuracy was 90%, 79% and 74%, respectively. The conclusion from this study is that LeukoScan is more accurate in detecting osteomyelitis, with better sensitivity and specificity in prosthetic joints. Compared with (111)indium white blood cell scans, LeukoScan++ gives superior images, and results are obtained in 1 to 6 hours without biohazard risk from handling blood products.

Use of technetium antigranulocyte monoclonal antibody Fab' fragments for the detection of osteomyelitis.

Accurate early diagnosis of osteomyelitis is critical for optimal clinical management. Conventional radiology (X-rays, CT) and nuclear medicine scans (bone, gallium, and technetium/indium white blood cell [WBC]) have limitations and drawbacks. The monoclonal antibody (MAb) ImmuRAID-MN3 (Immunomedics Inc., Morris Plains, NJ), a 99m-Tc Antigranulocyte Fab' fragment, recognizes a surface glycoprotein NCA-90/95 shared by granulocytes, carcino-embryonic antigen (CEA), and meconium antigen (MA). Intravenous injection of radiolabeled MAb enables in vivo labeling of human granulocytes and targets infected lesions in the bone and throughout the body. Technetium labeled Fab' fragments rapidly clear the blood pool and high-quality images can be obtained the same day, as early as 1 h postinjection. Results at our institution on 13 patients with clinically suspected osteomyelitis of infected long bones, prostheses, and diabetic foot ulcers were compared with the surgical/bacteriological verification of the presence or absence of infection. The MAb scan showed six true positives, six true negatives, and one false negative (very low grade infection). The procedure was safe, no clinical or laboratory adverse reactions were encountered. The MAb fragments are markedly less immunogenic than whole IgG, resulting in lower induction of human antimouse antibody (HAMA) titers. No HAMA to this MAb fragment has been detected in 24 patients (data from multiple institutions). Our preliminary results suggest that 99m-Tc ImmuRAID-MN3 is highly accurate for detection of osteomyelitis. This study is part of an ongoing multiinstitutional project sponsored by Immunomedics, Inc. to evaluate the efficacy and safety of this radiopharmaceutical.