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ORIGINAL RESEARCH article

Front. Immunol.

Sec. Inflammation

Volume 16 - 2025 | doi: 10.3389/fimmu.2025.1646134

This article is part of the Research TopicAdenosine Metabolism in Cardiovascular and Smooth MuscleView all 4 articles

Developing and validating anti-ADA2 single-chain antibodies coupled to alkaline phosphatase for diagnosing pleural tuberculosis

Provisionally accepted
Maksym  SkaldinMaksym Skaldin1José  M PorcelJosé M Porcel2Urpo  LamminmäkiUrpo Lamminmäki1Silvia  BielsaSilvia Bielsa2Andrey  ZavialovAndrey Zavialov3,4*
  • 1Turun yliopisto, Turku, Finland
  • 2Hospital Universitari Arnau de Vilanova, Lleida, Spain
  • 3Turku Centre for Biotechnology, University of Turku, Turku, Finland
  • 4Hainan Medical University, Haikou, China

The final, formatted version of the article will be published soon.

Adenosine deaminases ADA1 and ADA2 reduce adenosine concentrations, which regulate cellular immune responses to activation signals. It has been shown that ADA2 activity increases in the pleural fluid of patients with tuberculosis (TB). We engineered recombinant scFv-AP antibodies using phage display technology to select high-affinity binders against ADA2. These were incorporated into a sandwich ELISA, allowing for the precise measurement of ADA2 levels in pleural fluid. The assay was tested on pleural samples from 41 patients with TB and 47 with non-TB effusions, including those with malignancies and parapneumonic effusions. Results showed that ADA2 concentrations were significantly higher in patients with TB than in other groups, and the ADA2-based assay exhibited improved diagnostic specificity (91%) compared with total ADA testing (76%). A cutoff of 300 ng/mL for ADA2 yielded a sensitivity of 98% and a negative likelihood ratio of 0.03, effectively ruling out TB when the result was negative. The new ADA2 assay offers a simple, reliable, and more specific alternative for diagnosing pleural TB, with potential applications in other ADA2-related disorders.

Keywords: ADA2 (Adenosin deaminase 2), Pleural ADA, Pleural tuberculosis, pleural tuberculosis diagnosis, Single chain (scFv), ADA2 ELISA

Received: 12 Jun 2025; Accepted: 25 Jul 2025.

Copyright: © 2025 Skaldin, Porcel, Lamminmäki, Bielsa and Zavialov. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Andrey Zavialov, Turku Centre for Biotechnology, University of Turku, Turku, Finland

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