Clinical Evaluation of a Homemade Enzyme-Linked Immunospot Assay for the Diagnosis of Active Tuberculosis in China

• Published in: Molecular biotechnology 2011, Vol.47 (1), p.18-25
• Main Authors: Wu, Xueqiong, Li, Qiaoke, Liang, Yan, Yang, Yourong, Zhang, Junxian, Liang, Jianqin, Li, Lan, Tang, Fakuan, Wang, Ansheng
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Antigens, Bacterial - analysis; Antigens, Bacterial - isolation & purification; Bacterial Proteins - analysis; Bacterial Proteins - isolation & purification; Biochemistry; Biological and medical sciences; Biological Techniques; Biotechnology; Cell Biology; Chemistry; Chemistry and Materials Science; China - epidemiology; Diagnostic tests; Enzyme-Linked Immunospot Assay - methods; Enzymes; Female; Fundamental and applied biological sciences. Psychology; Genetic recombination; Human Genetics; Humans; Male; Middle Aged; Mycobacterium; Mycobacterium tuberculosis - genetics; Protein Science; Recombinant Fusion Proteins - analysis; Recombinant Fusion Proteins - isolation & purification; Retrospective Studies; Tuberculin Test; Tuberculosis; Tuberculosis, Pulmonary - diagnosis; Young Adult
• ISSN: 1073-6085; 1559-0305
• DOI: 10.1007/s12033-010-9307-0

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.