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Immune response patterns among early smear converter and non-converter tuberculosis patients initiated on DOTS
Last modified: 2020-02-25
Abstract
Background: Even in the era of valid chemotherapy, tuberculosis (TB) still remains one of the major public health threats, accounting for a substantial number of deaths worldwide, which is further worsen by its late smear conversion and subsequent treatment failure. Several factors attribute to tuberculosis treatment failure; intrinsic factors associated to weakened host immune system have been rarely explored.
Objective: The objective of this study was to understand the host immune response to TB by comparing Mycobacterium tuberculosis (Mtb) antigen-specific response patterns among early smear converter and non- converter tuberculosis patients after 2nd month of anti-TB treatment.
Methods: Health facility-based, case-control study was conducted on 60 newly diagnosed pulmonary TB patients (30 cases and 30 controls), who already initiated anti-TB treatment in selected health facilities in Addis Ababa. About 10 ml of heparinized venous blood sample was collected and Mtb antigen-specific immune responses were measured using enzyme-linked immunosorbent assay (ELISA). Data was entered using Epi-data (Version 3.1) and analyzed by SPSS (Version 25.0) and GraphPad Prism for Windows (Version 6.00). Logistic regression and non-parametric statistical test were used to determine the mean difference among groups. A pvalue <0.05 was considered statistically significant.
Results: We observed a significant difference in the mean cytokine concentration levels of PPDspecific IFN-γ (7,121 vs. 909, p = 0.00), TNF-α (1,361.37 vs. 167.45, p = 0.00) and IL-2 (407.34 vs. 53.36, p = 0.00) between the early and late smear converters, respectively. A similar difference was noted for ESAT-6-specific IFN- (6,917 vs. 800, p = 0.00), TNF- (1,198.8 vs. 167.6, p = 0.00) and IL-2 (434.2 vs. 46.5, p = 0.00) responses between the early and later smear converters, respectively.
Conclusions: Those patients with a history of prior TB treatment and a 3+ bacillary load were more likely to have unconverted smear status. A generally heightened increase in the Mtb-antigen specific immune responses in early smear converters possibly indicates the contribution of strong immune responses on the rate of smear conversion and possibly early recovery at later stage. Multifunctional T cell markers, often characterized by the production of IFN-γ, TNF-α and IL-2, could be considered as good biomarker pools to early identify TB treatment outcome.
Objective: The objective of this study was to understand the host immune response to TB by comparing Mycobacterium tuberculosis (Mtb) antigen-specific response patterns among early smear converter and non- converter tuberculosis patients after 2nd month of anti-TB treatment.
Methods: Health facility-based, case-control study was conducted on 60 newly diagnosed pulmonary TB patients (30 cases and 30 controls), who already initiated anti-TB treatment in selected health facilities in Addis Ababa. About 10 ml of heparinized venous blood sample was collected and Mtb antigen-specific immune responses were measured using enzyme-linked immunosorbent assay (ELISA). Data was entered using Epi-data (Version 3.1) and analyzed by SPSS (Version 25.0) and GraphPad Prism for Windows (Version 6.00). Logistic regression and non-parametric statistical test were used to determine the mean difference among groups. A pvalue <0.05 was considered statistically significant.
Results: We observed a significant difference in the mean cytokine concentration levels of PPDspecific IFN-γ (7,121 vs. 909, p = 0.00), TNF-α (1,361.37 vs. 167.45, p = 0.00) and IL-2 (407.34 vs. 53.36, p = 0.00) between the early and late smear converters, respectively. A similar difference was noted for ESAT-6-specific IFN- (6,917 vs. 800, p = 0.00), TNF- (1,198.8 vs. 167.6, p = 0.00) and IL-2 (434.2 vs. 46.5, p = 0.00) responses between the early and later smear converters, respectively.
Conclusions: Those patients with a history of prior TB treatment and a 3+ bacillary load were more likely to have unconverted smear status. A generally heightened increase in the Mtb-antigen specific immune responses in early smear converters possibly indicates the contribution of strong immune responses on the rate of smear conversion and possibly early recovery at later stage. Multifunctional T cell markers, often characterized by the production of IFN-γ, TNF-α and IL-2, could be considered as good biomarker pools to early identify TB treatment outcome.