Combined detection of T cell number secreting IFN-γ and IL-2 in
different tuberculosis populations and their clinical value
Abstract
Objective: The interferon-γ (IFN-γ) release assays still fail to meet
the diagnostic needs of etiology negative tuberculosis (TB) patients.
The purpose of this paper is to explore the value of the
IL-2-enzyme-linked immunospot (ELISPOT) assay in the auxiliary diagnosis
of TB. Methods: We recruited 127 TB patients, 49 non-TB patients with
other diseases (NTB), and 198 healthy people, whose peripheral blood
mononuclear cells were isolated and stimulated by Mtb-specific antigen
CFP-10/ESAT-6 fusion protein to study the changes of T cells secreting
IFN-γ and Interleukin-2 (IL-2) by ELISPOT method. Results: The
combination of IFN-γ and IL-2 had an area under the curve (AUC) of 0.867
(IFN-γ: 0.835, IL-2: 0.866) in the diagnosis of TB and could increase
the sensitivity of IFN-γ detection alone from 79.5% to 86.6%. The
cut-off value for IL-2 and IFN-γ was 16. IL-2 could increase the
positive diagnostic rates of IFN-γ-ELISPOT (-) in the etiologically
positive and negative ATB patients by 9.4% and 7.1%. In the ATB group,
the positive rates and the numbers of spot-forming cells (SFC) of IFN-γ
and IL-2 showed significant differences compared to the normal control
subjects and NTB group (P<0.05). And SFCs of IFN-γ-ELISPOT
were significantly higher than that of IL-2-ELISPOT in ATB patients.
Before the treatment, the SFC values of the etiologically positive TB
patients were higher than those of the etiologically negative patients.
However, this situation was totally reversed after anti-TB treatment.
After effective treatment, the positive rates and SFC values of IFN-γ
and IL-2 in TB patients decreased and exhibited a decreasing and
increasing trend in etiologically positive and negative TB patients,
respectively. Conclusions: The combination of IL-2 and IFN-γ could
improve the diagnostic sensitivity of single-factor detection in TB
patients and these two cytokines could be used as effective biomarkers
for the treatment monitoring in TB patients.