High Numbers of Interferon-γ-Producing T Cells and Low Titers of Anti-Tuberculous Glycolipid Antibody in Individuals with Latent Tuberculosis

High Numbers of Interferon-γ-Producing T Cells and Low Titers of Anti-Tuberculous Glycolipid Antibody in Individuals with Latent Tuberculosis

HEINNER GUIO,^1,3 YUGO ASHINO,¹ HIROKI SAITOH,¹ UMME RUMAN SIDDIQI,¹ MASAKO MIZUSAWA,^1,2 PENG XIAO,¹ ALONSO SOTO,³ ANDROS THEO¹ and TOSHIO HATTORI¹

¹Division of Emerging Infectious Diseases, Graduate School of Medicine, Tohoku University, Sendai, Japan
²Department of Respiratory Diseases, Internal Medicine, Tokyo Metropolitan Fuchu Hospital, Tokyo, Japan
³ALBIOTEC - Asociación Latinoamericana de Biotecnología, Lima, Perú

Latent tuberculosis infection (LTBI) is defined as an infection with Mycobacterium tuberculosis (MTB) without clinical, bacteriological, or radiological findings, and its early diagnosis is essential for eradication of tuberculosis. To identify LTBI, we measured the numbers of interferon-γ producing T cells, based on the ELISPOT assay, and the antibody titers in the sera to tuberculous glycolipid antigen (TBGL-Ab). Seventeen culture-confirmed TB patients, 13 controls from TB endemic areas (EC) and 13 controls from TB non-endemic areas (NEC) were enrolled. Peripheral blood mononuclear cells (2.5 × 10⁵ per well) were cultured on plates precoated with antibody against interferon-γ. ELISPOT response was defined as positive when the MTB-specific antigen-containing wells showed at least 6 spots and twice numbers of spots than negative control wells. ELISPOT responses were positive in 15 (88%), 8 (62%) and 4 (31%) subjects of TB, EC and NEC groups, respectively. The ELISPOT data differ between TB and NEC groups (p < 0.01) but not between TB and EC groups. In contrast, TBGL-Ab titers were elevated (> 2.0 U/ml) in 12 TB patients (71%), but only in one subject (8%) each from EC and NEC groups. These results indicate the high prevalence of LTBI in EC. In conclusion, LTBI is associated with positive ELISPOT assay and the low titer of TBGL-Ab, while positive results both in ELISPOT and TBGL-Ab assays indicate active TB. The low titer of TBGL-Ab is a helpful marker to identify LTBI in ELISPOT-positive individuals in TB endemic areas.

keywords —— interferon-γ producing T cells; TBGL antibody; active tuberculosis; latent tuberculosis

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Tohoku J. Exp. Med., 2010, 220, 21-25

Correspondence: Toshio Hattori, Division of Emerging Infectious Diseases, Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.

e-mail: thatto@m.tains.tohoku.ac.jp