Lymphocyte subset analysis in QuantiFERON-TB Gold Plus and T-Spot.TB for latent tuberculosis infection in rheumatoid arthritis

Publication date: Available online 18 October 2017
Source:Journal of Infection and Chemotherapy
Author(s): Hidetoshi Igari, Satoru Ishikawa, Takuya Nakazawa, Yoshihiro Oya, Hidekazu Futami, Mizue Tsuyuzaki, Kiminori Suzuki, Ryutaro Matsumura
Rheumatoid arthritis (RA) is an immune mediated inflammatory disorder, and immune suppressive drugs are prescribed. RA patients receiving treatments are in a kind of immunosuppressive condition that presents increased risk of developing active tuberculosis. Accurate diagnosis of latent tuberculosis infection (LTBI) is recommended for RA. QuantiFERON^®-TB Gold Plus (QFT-Plus), a novel IGRA, has two tubes (TB1 and TB2). TB2 is designed to elicit both CD4 and CD8 T-cell responses, with expected increased sensitivity. We conducted a cross-sectional study to compare two IGRAs, QFT-Plus and T-SPOT^®.TB (TSPOT), in RA. One hundred fifty-two RA patients (median age: 66.5 yrs) were enrolled. QFT-Plus and TSPOT were concurrently conducted. Lymphocyte subsets (CD4 T-cell and CD8 T-cell) were also measured. The positivity rates of QFT-Plus and TSPOT were 9.7% and 4.5%, respectively, with the difference being significant (P < 0.01). The positivity rates in TB1 and TB2 were 9.1% and 7.1%, respectively; the difference was not significant (P = 0.18). Patients with CD4 T-cell ≥650/μL and CD8 T-cell ≥400/μL had significantly higher positivity rates in both QFT-Plus and TSPOT in comparison with other groups (P < 0.01 and P < 0.05, respectively). QFT-plus demonstrated a higher positivity rate than TSPOT. However, there was little additional effect for detecting LTBI by TB2. Lymphocyte subsets were strongly associated with immune response in both QFT-Plus and TSPOT. LTBI should not be ruled out even with a negative IGRA result in patients with CD4 T-cell <650/μL or CD8 T-cell <400/μL.



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