Clinical evaluation of a homemade enzyme-linked immunospot assay for the diagnosis of active tuberculosis in China

Mol Biotechnol. 2011 Jan;47(1):18-25. doi: 10.1007/s12033-010-9307-0.

Abstract

The rapid diagnosis of smear-negative pulmonary tuberculosis (TB) and extrapulmonary TB is a significant problem in clinical practice. We evaluated the usefulness of a homemade enzyme-linked immunospot (ELISPOT) assay for the diagnosis of active TB in China. Seventy-eight healthy volunteers, 60 patients with active TB, and 32 patients with non-TB diseases were evaluated by tuberculin skin test (TST), an ELISPOT assay using a recombinant CFP-10/ESAT-6 fusion protein (rCFP-10/ESAT-6) as a stimulant, and T-SPOT-TB assay. The spot-forming cells (SFC) from 78 healthy subjects containing both PPD-positive and -negative persons was 3.7 ± 6.5. Among 31 diagnosed TB patients, the ELISPOT assay had a sensitivity of 67.7%, compared to a sensitivity of 77.4% for the T-SPOT-TB assay. The ELISPOT assay was more sensitive in smear-positive TB cases (76.9%) than in smear-negative TB cases (61.1%), while T-SPOT-TB had roughly similar sensitivities in smear-positive (76.9%) and smear-negative TB cases (77.8%). The specificity was 90.6% for ELISPOT and 78.1% for T-SPOT-TB among 32 subjects with non-TB diseases. The SFC of TB cases was significantly higher than that of non-TB disease cases, and the SFC of smear-positive TB cases was significantly higher than that of smear-negative TB cases (P < 0.01). We confirmed that the homemade ELISPOT assay appears more specific for the diagnosis of active TB than T-SPOT-TB. ELISPOT assay may be a useful method for the rapid diagnosis of active TB, especially for cases of smear-negative TB.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Antigens, Bacterial / analysis*
  • Antigens, Bacterial / isolation & purification
  • Bacterial Proteins / analysis*
  • Bacterial Proteins / isolation & purification
  • China / epidemiology
  • Enzyme-Linked Immunospot Assay / methods*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / genetics
  • Recombinant Fusion Proteins / analysis*
  • Recombinant Fusion Proteins / isolation & purification
  • Retrospective Studies
  • Tuberculin Test*
  • Tuberculosis, Pulmonary / diagnosis*
  • Young Adult

Substances

  • Antigens, Bacterial
  • Bacterial Proteins
  • ESAT-6 protein, Mycobacterium tuberculosis
  • Recombinant Fusion Proteins