Gamma interferon as a superior diagnostic marker in tuberculous pleural effusion: A comparative analysis with adenosine deaminase

Abstract

Background: The diagnosis of tuberculous pleural effusion (TPE) poses a massive problem during tuberculosis (TB) control worldwide. This study set out to find the role of Interferon Gamma (IFN-γ) and Adenosine Deaminase (ADA) in pleural fluid as markers for early diagnosis of TPE to improve the accuracy and, hence, the opportunity for early and effective intervention for patients. Aims and Objectives: (i) The aims and objectives of the study are to compare the levels of IFN-γ and ADA in pleural fluid samples from patients with tuberculous and non-TPEs; (ii) to determine the diagnostic accuracy of these biomarkers in differentiating TPE from other causes; and (iii) to analyze the correlation of IFN-γ and ADA levels with other routine diagnostic parameters for TB. Materials and Methods: The study adopted a forwardlooking, case–control methodology to compare outcomes across groups. One hundred individuals presenting with pleural effusion were selected for participation. This cohort was divided evenly, with 50 individuals identified with TPE and 50 showing non-tuberculous types of effusion, including those caused by parapneumonic and cancerous processes. Eligible participants were aged between 20 and 60 years and tested negative for the human immunodeficiency virus. Exclusion criteria included pleural effusion arising from viral infections, pregnancy or breastfeeding status, adverse drug reactions affecting the skin, or empyema. Thoracocentesis was performed to collect pleural fluid following participants’ informed consent under sterile conditions. The analysis of pleural fluid encompassed measurements of IFN-γ through enzyme-linked immunosorbent assay techniques and ADA levels through an ADA assay kit. In addition, venous blood was drawn to conduct routine hematological and biochemical tests, including evaluating serum lactate dehydrogenase, total protein, albumin, and cholesterol levels. Results: It was found that the mean level of IFN-γ was significantly (P < 0.00001) higher in patients with TPE, 186.66 ± 134.46 pg/mL, as compared to the level in non-tuberculous effusion 47.53 ± 68.94 pg/mL. Similarly, the difference in ADA level was also significant (P = 0.016) between the two groups. The mean level of ADA was significantly (P = 0.016) higher in TPE, 135.93 ± 239 U/L, compared to the level in non-tuberculous effusion, 58.86 ± 87.83 U/L. Conclusion: The significant elevation in IFN-γ and ADA levels in TPE patients re-emphasizes their potential as specific markers in this clinical condition and suggests considering IFN-γ in combination with ADA as valuable parameters in the differentiation of tuberculous from non-tuberculous effusions and thereby, this advancement in the realm of quick markers of diagnosis would play a crucial role in the refinement of diagnosis strategy in TB which would be of immense help in improving the patients’ outcome.