title: Diagnosis of intestinal tuberculosis using a monoclonal antibody to Mycobacterium tuberculosis.
abstract: OBJECTIVE
  To investigate the utility of immunohistochemical (IHC) staining with an antibody to Mycobacterium tuberculosis (M. tuberculosis) for the diagnosis of intestinal tuberculosis (TB).
  
  
  METHODS
  We retrospectively identified 10 patients (4 males and 6 females; mean age = 65.1 ± 13.6 years) with intestinal TB. Clinical characteristics, including age, gender, underlying disease, and symptoms were obtained. Chest radiograph and laboratory tests, including sputum Ziehl-Neelsen (ZN) staining, M. tuberculosis culture, and sputum polymerase chain reaction (PCR) for tubercle bacilli DNA, as well as Tuberculin skin test (TST) and QuantiFERON-TB gold test (QFT), were examined. Colonoscopic records recorded on the basis of Sato's classification were also reviewed, in addition to data from intestinal biopsies examined for histopathological findings, including hematoxylin and eosin staining, and ZN staining, as well as M. tuberculosis culture, and PCR for tubercle bacilli DNA. For the present study, archived formalin-fixed paraffin-embedded (FFPE) intestinal tissue samples were immunohistochemically stained using a commercially available species-specific monoclonal antibody to the 38-kDa antigen of the M. tuberculosis complex. These sections were also stained with the pan-macrophage marker CD68 antibody.
  
  
  RESULTS
  From the clinical data, we found that no patients were immunocompromised, and that the main symptoms were diarrhea and weight loss. Three patients displayed active pulmonary TB, six patients (60%) had a positive TST, and 4 patients (40%) had a positive QFT. Colonoscopic findings revealed that all patients had type 1 findings (linear ulcers in a circumferential arrangement or linear ulcers arranged circumferentially with mucosa showing multiple nodules), all of which were located in the right hemicolon and/or terminal ileum. Seven patients (70%) had concomitant healed lesions in the ileocecal area. No acid-fast bacilli were detected with ZN staining of the intestinal tissue samples, and both M. tuberculosis culture and PCR for tubercle bacilli DNA were negative in all samples. The histopathological data revealed that tuberculous granulomas were present in 4 cases (40%). IHC staining in archived FFPE samples with anti-M. tuberculosis monoclonal antibody revealed positive findings in 4 patients (40%); the same patients in which granulomas were detected by hematoxylin and eosin staining. M. tuberculosis antigens were found to be mostly intracellular, granular in pattern, and primarily located in the CD68(+) macrophages of the granulomas.
  
  
  CONCLUSIONS
  IHC staining with a monoclonal antibody to M. tuberculosis may be an efficient and simple diagnostic tool in addition to classic examination methods for the diagnosis of intestinal TB.
authors: Department of Infectious, Respiratory, and Digestive Medicine, Faculty of Medicine, University of the Ryukyus, Okinawa 903-0215, Japan.
authors: Yasushi
authors: Y
authors: Ihama
authors: Akira
authors: A
authors: Hokama
authors: Kenji
authors: K
authors: Hibiya
authors: Kazuto
authors: K
authors: Kishimoto
authors: Manabu
authors: M
authors: Nakamoto
authors: Tetsuo
authors: T
authors: Hirata
authors: Nagisa
authors: N
authors: Kinjo
authors: Haley L
authors: HL
authors: Cash
authors: Futoshi
authors: F
authors: Higa
authors: Masao
authors: M
authors: Tateyama
authors: Fukunori
authors: F
authors: Kinjo
authors: Jiro
authors: J
authors: Fujita
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D003113:Colonoscopy; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis; D012189:Retrospective Studies; D016896:Treatment Outcome; D014385:Tuberculosis, Gastrointestinal / Q000175:diagnosis*; D000097382:CD68 Molecule
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; C067980:CD68 antigen, human; D000097382:CD68 Molecule
keywords: Colonoscopy; Immunohistochemistry; Intestinal tuberculosis; Monoclonal antibody; Mycobacterium tuberculosis