Background
The role of T-cell responses against Mycobacterium tuberculosis antigens in tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is unclear.
Methods
Peripheral blood mononuclear cells from 45 HIV patients with treated TB, of whom 12 developed TB-IRIS, were collected at weeks 0, 2, and 6 of antiretroviral therapy (ART). Production of interferon-γ (IFN-[γ]) and interleukin-2 by T cells after stimulation with purified protein derivative (PPD) or early secretory antigenic target-6 (ESAT-6) and T-cell expressions of CCR5 and CXCR3 were assessed by flow cytometry. IFN-γ and CXCL10 were assayed by enzyme-linked immunosorbent assay.
Results
TB-IRIS patients had higher proportions of PPD- and ESAT-6–reactive IFN-γ+CD4+ and CD3+CD4- T cells at weeks 0, 2, and 6. IFN-γ levels were also higher in peripheral blood mononuclear cell culture supernatants at all times with PPD but only at weeks 2 and 6 with ESAT-6. There were few differences for interleukin-2. CXCL10 levels in supernatants after PPD and ESAT-6 stimulation were only higher at week 6. CXCR3+/CCR5+CD4+ T cells were higher at week 2, and CCR5+CD4+ T cells were higher at week 6.
Conclusions
TB-IRIS is associated with Th1 responses against M. tuberculosis antigens by CD4+ and CD3+CD4- T cells that are present before ART and amplified afterward. It is unclear if these cause immunopathology or reflect a high pathogen load.
Reliable and ease of testing individual specimens could make the Xpert HIV-1 viral load assay an efficient alternative method for ART monitoring in clinical management of HIV disease in resource-limited settings. The rapid test results (less than 2 h) could help in making an immediate clinical decision, which further strengthens patient care.
Coccidian parasites continue to be the most common aetiological agent of diarrhoea among patients with HIV. The increasing trend of positivity of both cystoisosporiasis and cryptosporidiosis over the study period and the high positivity of cryptosporidiosis in patients with lower CD4+ T-cell counts are issues of serious concern. The findings call for the need for the early diagnosis of coccidian parasites and appropriate intervention among HIV-infected patients.
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