The auxiliary diagnosis value of enzyme-linked immunosorbent spot assay and flow cytometry in detection of IFN-γ in tuberculous pleurisy / 中华检验医学杂志

ABSTRACT

Objective To explore the value of IFN-γ produced or secreted by CD+4 T Lymphocytes from pleural effusion mononuclear cells for the diagnosis of tuberculous pleurisy(plTB).Methods The PEMCs of 40 patients with tuberculous pleural effusion and 30 patients with malignancy pleural effusion were selected as the tuberculosis and disease control groups, then co-cultured with the early secretory antigenic target 6 (ESAT-6) and culture filtered protein 10 (CFP-10) fusion protein (E/C).The numbers of spot forming cells(SFC) secreting IFN-γ were enumerated by ELISpot and the ratios of cells producing IFN-γ were detected by flow cytometry and intracellular cytokine staining.Moreover, the two indicators were compared between tuberculosis and disease control groups to evaluate the 2 methods detecting IFN-γ in the diagnosis of plTB.Results After E/C stimulation, the numbers of SFC were 205(125-450)SFC/5×104 PEMC in tuberculosis group and 5(2-18)SFC/5×104 PEMC in disease control group by ELISpot.The difference between two groups was statistically significant (U= 20.00, P<0.01).The proportion of IFN-γ-secreting CD+4 T lymphocytes was 3.27% (1.81%-7.34%) in tuberculosis group and 0.12% (0.06%-0.46%) in control group detected by FCM. The difference between the two groups was statistically significant (U=45.00, P<0.01).The indicators of ELISpot in detection of IFN-γ which was secreted by PEMC after co-cultured with E/C were as follows sensitivity 92.5% (37/40), specificity 80.0% (24/30), positive predictive value 0.86, negative predictive value 0.89, positive likelihood ratio 4.63, negative likelihood ratio 0.09 and accuracy 87.1%;and for FCM, they were 87.5% (35/40), 90.0% (27/30), 0.92, 0.84, 8.75 and 0.14, respectively and accuracy 88.6%.Conclusion After E/C stimulation, the assay for IFN-γ-secreting CD+4 T lymphocytes by FCM and ELISpot is highly sensitive and specific for diagnosis of plTB as an auxiliary method.