Lymphocyte proliferation to mycobacterial antigens is detectable across a spectrum of HIV-associated tuberculosis

Abstract

BackgroundIdentifying novel TB diagnostics is a major public health priority. We explored the diagnostic characteristics of antimycobacterial lymphocyte proliferation assays (LPA) in HIV-infected subjects with latent or active TB.MethodsHIV-infected subjects with bacille Calmette Guérin (BCG) scars and CD4 counts ≥ 200 cells/mm3 entering a TB booster vaccine trial in Tanzania had baseline in vivo and in vitro immune tests performed: tuberculin skin tests (TST), LPA and five day assays of interferon gamma (IFN-γ) release. Assay antigens were early secreted antigenic target 6 (ESAT-6), antigen 85 (Ag85), and Mycobacterium tuberculosis whole cell lysate (WCL). Subjects were screened for active TB at enrollment by history, exam, sputum smear and culture. We compared antimycobacterial immune responses between subjects with and without latent or active TB at enrollment.ResultsAmong 1885 subjects screened, 635 had latent TB and 13 had active TB. Subjects with latent TB were more likely than subjects without TB to have LPA responses to ESAT-6 (13.2% vs. 5.5%, P < 0.0001), Ag85 (18.7% vs. 3.1%, P < 0.0001), and WCL (45.7% vs. 17.1%, P < 0.0001). Subjects with active TB also were more likely than those without active TB to have detectable LPA responses to ESAT-6 (38.5% vs. 8.1%, P = 0.0001), Ag85 (46.2% vs. 8.5%, P < 0.0001), and WCL (61.5% vs. 27.0%, P = 0.0053). In subjects with a positive TST, LPA responses to ESAT-6, Ag85 and WCL were more common during active TB (p < 0.0001 for all tests). In diagnosing active TB, in vivo and in vitro tests of mycobacterial immune responses had sensitivity and specificity as follows: TST 84.6% and 65.5%, ESAT-6 LPA 38.5% and 92.0%, Ag85 LPA 46.2% and 91.5%, and WCL LPA 61.5% and 73.0%. Detectable LPA responses were more common in patients with higher CD4 counts, and higher HIV viral loads.ConclusionLymphoproliferative responses to mycobacteria are detectable during HIV-associated active TB, and are less sensitive but more specific than TST.Trial registrationClinicalTrials.gov Identifier NCT00052195.

Interferon γ Responses to Mycobacterial Antigens Protect against Subsequent HIV‐Associated Tuberculosis

“…Our study differs from previous cross-sectional studies in people with HIV that have shown greater frequency of IFN-γ responses in subjects with active or latent TB compared to subjects without active or latent TB [9–11, 38, 39]. These previous results might suggest that positive IFN-γ responses are always associated with an increased risk of TB disease in the future.…”

Increased percentage of IFN-γ producing CD56+CD3+ cells in active tuberculosis patients upon CFP-10 stimulation of peripheral mononuclear cells

“…PPD or CFP-10 were increased in PTB and TSTþ HHC, compared to TSTÀ Non HHC, supporting that all of these responses differentiate these groups regardless of the stimuli used, and BCG vaccination. These findings are in agreement with immune response against PPD, CFP-10 or ESAT-6 determined by proliferation index [11,27], with IFN-g in cell culture supernatants [4,28], and with the percentages of IFN-g producing CD4 þ and CD8 þ lymphocytes where patients and latent infected individuals are differentiated from non-infected individuals [29,30], unlike the report by Cardoso et al in Brazil, who found that 8/10 TST-controls produced IFN-g in response to ESAT-6 [6].…”

Multiple mycobacterial antigens are targets of the adaptive immune response in pulmonary sarcoidosis

“…However, we have shown in a previous study that in peripheral blood mononuclear cells, multiple antigens induce IFN-γ production [8], as well as that T cells from sarcoidosis BAL can produce an IFN-γ response to both mycobacterial ESAT-6 and KatG [14]. …”