Abstract
Background: Tuberculosis is a major public health challenge in the resource-limited endemic setting of sub-Saharan Africa. The diagnostic challenge becomes worse for smear-negative TB cases. Even if efforts for non-sputum-based TB diagnostic and prognostic biomarkers, there was limited data on blood-based immunological biomarkers among smear-negative PTB patients.Therefore, we assessed the phenotypic profile (HLA-DR, CD-38, Ki-67) of M. tuberculosis specific CD4 + T cells expressing dual IFN-γ and TNF-α cytokines from smear negative PTB patients in Addis Ababa, Ethiopia. Methodology: An institutional-based longitudinal cohort study was conducted in Addis Abeba, Ethiopia, on new smear-negative PTB who were adult and HIV-negative in comparison with multiple comparator groups. A total of 149 (confirmed patients with non-TB respiratory disease -33, smear-negative TB-29, smear-positive TB-34, apparently healthy - 53) study participants was enrolled. The expression level of activation (HLA-DR, CD-38) and proliferation (Ki-67) markers from dual IFN-γ and TNF-α cytokines expressing PPD specific CD4 + T cells were assessed after surface and intracellular cytokine staining. To confirm the presence of M. tuberculosis, MGIT/LJ culture, PCR, and smear microscopy were performed. Result: The overall level of HLA-DR and CD-38 expression in smear-negative and positive pulmonary TB patients were substantially higher than that of confirmed non-TB respiratory illness, apparently healthy QFT positive and negative study participants (p-value = 0.0127, p-value < 0.0001, p-value = 0.0043, p-value <0.0001, respectively) before commencing anti TB treatment. Also, among the smear-negative and positive pulmonary TB cohort, the expression of CD-38, HLA-DR, and HLA-DR + CD-38 + expression was reduced in the second month and six-month cohort compared with baseline data (p-value= < 0.0001, p-value = 0.00365, p -value = 0.0001, respectively). Conclusion: In this study, we found the diagnostic and prognostic potential of activation markers, particularly CD-38, in smear-negative PTB patients from dual M. tuberculosis-specific IFN-γ + TNF-α+ cytokine producing CD4 + T cells in both the presumed ex vivo and antigen-specific stimulation assays.