A comparative analysis of two interferon-γ releasing assays to detect past tuberculosis infections in Japanese rheumatoid arthritis patients

Abstract

Both assays were equally useful with high specificities, but may falsely identify past tuberculosis infection owing to low sensitivities. In patients with low total and CD4-positive lymphocyte counts, both assays might give higher rates of false negative results.

Tuberculosis comorbidity with rheumatoid arthritis: Gene signatures, associated biomarkers, and screening

“…In RA patients receiving methotrexate, a positive correlation has been observed between CD4 and CD8 lymphocyte counts with the positive results of QFT and T-Spot tests. 94 Similar to the previous study, one evaluation in Japan showed in RA patients underlying treatment with anti-TNF agents, higher positive results of QFT-Plus and T-Spot tests were associated with CD4 T-cell >650/μl and CD8 T-cell >400/ μl compared to other groups and the rate of negative results increase with CD4 and CD8 T-cell less than these values. 78 As a result, in RA patients receiving DMARD or anti-TNF agents, reduction in lymphocyte count and activity can cause unreliable IGRA results, so assessment of TB just based on the IFN-γ value may not be an appropriate approach.…”

“…Another important finding is that monitoring LTBI in patients receiving DMARD or anti‐TNF agents can lead to false‐negative IGRA results. In RA patients receiving methotrexate, a positive correlation has been observed between CD4 and CD8 lymphocyte counts with the positive results of QFT and T‐Spot tests 94 . Similar to the previous study, one evaluation in Japan showed in RA patients underlying treatment with anti‐TNF agents, higher positive results of QFT‐Plus and T‐Spot tests were associated with CD4 T‐cell >650/μl and CD8 T‐cell >400/μl compared to other groups and the rate of negative results increase with CD4 and CD8 T‐cell less than these values 78 .…”

The performance of the TBAg/PHA ratio in the diagnosis of active TB disease in immunocompromised patients

“…Although T-SPOT assay has limited specificity for the diagnosis of ATB in high endemic countries, this assay has been broadly used for detection of MTB infection worldwide. Except for the limited specificity, a decreased sensitivity of T-SPOT assay in immunocompromised patients has been noticed (Pan et al, 2015;Dittrich and Lehmann, 2012;Iwagaitsu et al, 2016). The interpretation of T-SPOT data sometimes can become ambiguous, especially when spot numbers in antigen-containing wells are low in immunocompromised patients (Dittrich and Lehmann, 2012).…”

“…The reason for this may be that host immune status affects the results of T-SPOT assay. Some factors, such as age, over-weight, longer periods of illness before hospitalization and immunosuppressive therapy may contribute to reduced or even negative T-SPOT results (Hadaya et al, 2013;Cai et al, 2014;Pan et al, 2015;Dittrich and Lehmann, 2012;Iwagaitsu et al, 2016). Therefore, interpretation of T-SPOT results would become ambiguous especially in patients with immunocompromised status (Dittrich and Lehmann, 2012).…”

Systematic literature review informing the 2022 EULAR recommendations for screening and prophylaxis of chronic and opportunistic infections in adults with autoimmune inflammatory rheumatic diseases

“…Disagreement between TST and IGRA has led some authors to suggest that both tests should be performed in high-risk patients (travelling or coming from endemic regions) and/or in countries with high TB-burden 39 49 51. On the other hand, Quantiferon and enzyme-linked immunosorbent spot (ELISpot), two IGRA test platforms, appear to have good concordance52–55 (table 2). Several studies have shown that IGRA display a better performance compared with TST, having better sensitivity and specificity and being associated more closely with TB risk factors 13 14 17 19 25 30 55–57.…”