Imbalanced effector and regulatory cytokine responses may underlie mycobacterial immune restoration disease

Emergence of Polyfunctional Cytotoxic CD4+ T Cells in Mycobacterium avium Immune Reconstitution Inflammatory Syndrome in Human Immunodeficiency Virus-Infected Patients

Background

Immune reconstitution inflammatory syndrome (IRIS) is an aberrant inflammatory response in individuals with advanced human immunodeficiency virus (HIV) infection, after antiretroviral therapy (ART) initiation. The pathogenesis of Mycobacterium avium complex (MAC)-associated IRIS has not been fully elucidated.

Methods

We investigated monocyte and CD4+ T-cell responses in vitro, tumor necrosis factor (TNF) expression in tissues, and plasma cytokines and inflammatory markers, in 13 HIV-infected patients with MAC-IRIS and 14 HIV-uninfected patients with pulmonary MAC infection.

Results

Prior to ART, HIV-infected compared with HIV-uninfected patients, had reduced TNF+ monocytes (P = .013), although similar cytokine (interferon gamma [IFN-γ], TNF, interleukin 2 [IL-2], and interleukin 17 [IL-17])-expressing CD4+ T cells. During IRIS, monocyte cytokine production was restored. IFN-γ+ (P = .027), TNF+ (P = .004), and polyfunctional CD4+ T cells (P = 0.03) also increased. These effectors were T-betlow, and some expressed markers of degranulation and cytotoxic potential. Blockade of cytotoxic T-lymphocyte associated protein 4 and lymphocyte activation gene-3 further increased CD4+ T-cell cytokine production. Tissue immunofluorescence showed higher proportions of CD4+ and CD68+ (monocyte/macrophage) cells expressed TNF during IRIS compared with HIV-uninfected patients. Plasma IFN-γ (P = .048), C-reactive protein (P = .008), and myeloperoxidase (P < .001) levels also increased, whereas interleukin 10 decreased (P = .008) during IRIS.

Conclusions

Advanced HIV infection was associated with impaired MAC responses. Restoration of monocyte responses and expansion of polyfunctional MAC-specific T-betlow CD4+ T cells with cytotoxic potential after ART initiation may overwhelm existing regulatory and inhibitory mechanisms, leading to MAC-IRIS.

Human Immunodeficiency Virus in the Brain-Culprit or Facilitator?

Introduction:

Human immunodeficiency virus (HIV) enters the brain early, where it can persist, evolve, and become compartmentalized. Central nervous system (CNS) disease can be attributed to HIV alone or to the complex interplay between the virus and other neurotropic pathogens.

Aim:

The current review aims to describe the direct impact of HIV on the brain as well as its relationship with other pathogens from a practitioner’s perspective, to provide a general clinical overview, brief workup, and, whenever possible, treatment guidance.

Methods:

A review of PubMed was conducted to identify studies on neuropathogenesis of HIV in relation to host responses. Furthermore, the interaction between the CNS pathogens and the host damage responses were revised in the setting of advanced and also well-controlled HIV infection.

Results:

Similar to other pathogens, HIV leads to CNS immune activation, inflammation, and viral persistence. Therefore, almost half of the infected individuals present with neurocognitive disorders, albeit mild. Compartmentalized HIV in the CNS can be responsible in a minority of cases for the dramatic presentation of symptomatic HIV escape. Disruption of the immune system secondary to HIV may reactivate latent infections or allow new pathogens to enter the CNS. Opportunistic infections with an inflammatory component are associated with elevated HIV loads in the cerebrospinal fluid and also with greater cognitive impairment. The inflammatory immune reconstitution syndrome associated with CNS opportunistic infections can be a life-threatening condition, which needs to be recognized and managed by efficiently controlling the pathogen burden and timely balanced combination antiretroviral therapy. Latent neurotropic pathogens can reactivate in the brain and mimic HIV-associated severe neurological diseases or contribute to neurocognitive impairment in the setting of stable HIV infection.

Conclusions:

As HIV can be responsible for considerable brain damage directly or by facilitating other pathogens, more effort is needed to recognize and manage HIV-associated CNS disorders and to eventually target HIV eradication from the brain.

HIV-1 tuberculosis-associated immune reconstitution inflammatory syndrome

Patients co-infected with HIV-1 and tuberculosis (TB) are at risk of developing TB-associated immune reconstitution inflammatory syndrome (TB-IRIS) following commencement of antiretroviral therapy (ART). TB-IRIS is characterized by transient but severe localized or systemic inflammatory reactions against Mycobacterium tuberculosis antigens. Here, we review the risk factors and clinical management of TB-IRIS, as well as the roles played by different aspects of the immune response in contributing to TB-IRIS pathogenesis.

Tuberculosis and HIV Coinfection

Tuberculosis (TB) and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) constitute the main burden of infectious disease in resource-limited countries. In the individual host, the two pathogens, Mycobacterium tuberculosis and HIV, potentiate one another, accelerating the deterioration of immunological functions. In high-burden settings, HIV coinfection is the most important risk factor for developing active TB, which increases the susceptibility to primary infection or reinfection and also the risk of TB reactivation for patients with latent TB. M. tuberculosis infection also has a negative impact on the immune response to HIV, accelerating the progression from HIV infection to AIDS. The clinical management of HIV-associated TB includes the integration of effective anti-TB treatment, use of concurrent antiretroviral therapy (ART), prevention of HIV-related comorbidities, management of drug cytotoxicity, and prevention/treatment of immune reconstitution inflammatory syndrome (IRIS).

Immune reconstitution inflammatory syndrome in HIV-infected patients

Access to antiretroviral therapy (ART) is improving worldwide. Immune reconstitution inflammatory syndrome (IRIS) is a common complication of ART initiation. In this review, we provide an overview of clinical and epidemiological features of HIV-associated IRIS, current understanding of pathophysiological mechanisms, available therapy, and preventive strategies. The spectrum of HIV-associated IRIS is described, with a particular focus on three important pathogen-associated forms: tuberculosis-associated IRIS, cryptococcal IRIS, and Kaposi's sarcoma IRIS. While the clinical features and epidemiology are well described, there are major gaps in our understanding of pathophysiology and as a result therapeutic and preventative strategies are suboptimal. Timing of ART initiation is critical to reduce IRIS-associated morbidity. Improved understanding of the pathophysiology of IRIS will hopefully enable improved diagnostic modalities and better targeted treatments to be developed.

Immune response to Leishmania antigens in an AIDS patient with mucocutaneous leishmaniasis as a manifestation of immune reconstitution inflammatory syndrome (IRIS): a case report

BACKGROUND

After the onset of HAART, some HIV-infected individuals under treatment present a exacerbated inflammation in response to a latent or a previously treated opportunistic pathogen termed immune reconstitution inflammatory syndrome (IRIS). Few reports of tegumentary leishmaniasis have been described in association with IRIS. Moreover, the immunopathogenesis of IRIS in association with Leishmania is unclear.

CASE PRESENTATION

The present study reports on a 29-year-old HIV-infected individual who developed mucocutaneous leishmaniasis associated with immune reconstitution inflammatory syndrome (IRIS) five months following highly active antiretroviral therapy (HAART). Severe lesions resulted in the partial destruction of the nasal septum, with improvement observed 15 days after treatment with Amphotericin B and corticosteroids. The immune response of this patient was evaluated before and after the lesions healed. IRIS was diagnosed in association with high levels of TNF-α and IL-6. Decreased production of IFN-γ and a low IFN-γ/IL-10 ratio were also observed in response to Leishmania antigens. After receiving anti-leishmanial treatment, the individual's specific Th1 immune response was restored.

CONCLUSION

The results suggest that the production of inflammatory cytokines by unstimulated T-lymphocytes could contribute to occurrence of leishmaniasis associated with IRIS.

The immune pathogenesis of immune reconstitution inflammatory syndrome associated with highly active antiretroviral therapy in AIDS

The present study investigated the immunological pathogenesis of immune reconstitution inflammatory syndrome (IRIS) in acquired immunodeficiency syndrome (AIDS) patients undergoing highly active antiretroviral therapy (HAART). A total of 238 patients with AIDS who received initial HAART were included in this prospective cohort study. Blood samples were collected immediately, at baseline, at week 12, and at week 24 after initial HAART and at the onset of IRIS. Lymphocyte subsets, Th1 and Th2 cytokines, and interleukin (IL)-7 levels were measured by flow cytometry or ELISA. Among the 238 patients with AIDS who received HAART, 47 patients developed IRIS. The percentages of CD4(+) and CD8(+) naive, memory, and activated cells exhibited no significant differences between AIDS patients with and without IRIS 24 weeks after initial HAART. The percentage of CD4(+)CD25(+)Foxp3(+) regulatory T cells was lower in IRIS patients than in non-IRIS patients before HAART, 12 weeks after HAART, 24 weeks after HAART, and at the onset of IRIS. IL-2 and interferon (IFN)-γ levels were significantly higher at week 4 and at the onset of IRIS in IRIS patients than in non-IRIS patients. In contrast, IL-4 and IL-10 levels were significantly lower at week 4 and at the onset of IRIS in IRIS patients than in non-IRIS patients. Plasma IL-7 decreased gradually with the progression of HAART. The level of IL-7 was higher in IRIS patients than in non-IRIS patients at all follow-up time points. An imbalance of Th1/Th2 cytokines, a consistently low CD(+)CD25(+)Fox3(+) percentage, and a high IL-7 level may be crucial in the pathogenesis of IRIS in AIDS patients who had received HAART.

Leishmaniasis as a Manifestation of Immune Reconstitution Inflammatory Syndrome (IRIS) in HIV-Infected Patients: A Literature Review

INTRODUCTION

After the onset of highly active antiretroviral therapy (HAART), some HIV-infected patients present a severe inflammation in response to a latent or a previously treated opportunistic pathogen termed immune reconstitution inflammatory syndrome (IRIS). Few reports of tegumentary and visceral leishmaniasis have been described in association with IRIS.

METHODS

A systematic literature review of IRIS in association with leishmaniasis identified 34 reported cases.

RESULTS AND DISCUSSION

The majority of these occurred in males 4 months following the onset of HAART. The mean CD4 count before HAART was 94 ± 77 cells/mm³ increasing to 5 times the initial value between the onset of HAART and IRIS presentation. Visceral leishmaniasis and post-kala-azar dermal leishmaniasis were the most commonly reported clinical manifestations, followed by tegumentary leishmaniasis and uveitis.

CONCLUSIONS

Commonly found characteristics included cutaneous involvement, regardless of Leishmania species; appearance of lesions unrelated to time of probable Leishmania infection; rapid recovery of CD4 count following HAART; and rapid progression.

The immunopathogenesis of the HIV tuberculosis immune reconstitution inflammatory syndrome

HIV-1 patients co-infected with some pathogens are at risk of developing the immune reconstitution inflammatory syndrome (IRIS) when initiating antiretroviral therapy (ART). IRIS is characterized by inflammation leading to the clinical worsening of a treated infection or the unmasking of a previously undiagnosed condition or infection. It is commonly associated with tuberculosis (TB), 8-43% of the HIV-TB co-infected patients prescribed with antitubercular treatment and ART develop TB-IRIS. Although IRIS has been recognized for over 20 years, relatively little was known until recently about its pathogenesis. Despite these advances in understanding IRIS, there remains no immune biomarker for diagnostic or prognostic purposes. Here, we review the risk factors associated with TB-IRIS, the challenges in studying this syndrome, and how T lymphocytes, dysregulated cytokine responses, and innate immunity may contribute to the development of TB-IRIS.

HIV-1 and the immune response to TB

TB causes 1.4 million deaths annually. HIV-1 infection is the strongest risk factor for TB. The characteristic immunological effect of HIV is on CD4 cell count. However, the risk of TB is elevated in HIV-1 infected individuals even in the first few years after HIV acquisition and also after CD4 cell counts are restored with antiretroviral therapy. In this review, we examine features of the immune response to TB and how this is affected by HIV-1 infection and vice versa. We discuss how the immunology of HIV-TB coinfection impacts on the clinical presentation and diagnosis of TB, and how antiretroviral therapy affects the immune response to TB, including the development of TB immune reconstitution inflammatory syndrome. We highlight important areas of uncertainty and future research needs.

Pathogenesis and prevention of immune reconstitution disease during antiretroviral therapy

The risks of unmasking and paradoxical forms of immune reconstitution disease in HIV-infected patients starting antiretroviral therapy (ART) are fuelled by a combination of the late presentation of patients with advanced immunodeficiency, the associated high rates of opportunistic infections (OIs) and the need for rapid initiation of ART to minimize overall mortality risk. We review the risk factors and our current knowledge of the immunopathogenesis of immune reconstitution disease, leading to a discussion of strategies for prevention. Initiation of ART at higher CD4 counts, use of OI-preventive therapies prior to ART eligibility, intensified screening for OIs prior to ART initiation and optimum therapy for OIs are all needed. In addition, use of a range of pharmacological agents with immunosuppressive and immunomodulatory activity is being explored.

Circulating inflammatory biomarkers can predict and characterize tuberculosis-associated immune reconstitution inflammatory syndrome

OBJECTIVE

To identify inflammatory biomarker profiles during paradoxical and unmasking tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS), and determine whether differences in biomarkers prior to antiretroviral therapy (ART) predict subsequent development of TB-IRIS.

DESIGN

Case-control study within a cohort of patients initiating ART in South Africa (n = 498).

METHODS

Participants were followed up for 24 weeks for development of TB-IRIS. Plasma samples were collected at baseline and presentation with symptoms. Groups of cases and controls were as follows: pre-ART TB and developed paradoxical TB-IRIS (n = 9); pre-ART TB but no IRIS (n = 12); no pre-ART TB but developed unmasking TB-IRIS (n = 13); no pre-ART TB and no TB or IRIS during treatment (n = 12). Concentrations of 18 cytokines and chemokines, and C-reactive protein (CRP), were measured and compared.

RESULTS

Event samples were drawn a median of 28 days after ART initiation [interquartile range (IQR) 14-56 days]. During paradoxical TB-IRIS events, there were lower median concentrations of interleukin-10 [IL-10; 22.1 (IQR 15.3-34.9) vs. 82.2 (29.4-128.4) pg/ml, P = 0.047] and monocyte chemotactic protein-1 [MCP-1; 27.6 (20.0-29.7) vs. 71.4 (40.6-77.8) pg/ml, P = 0.005], and higher CRP: IL-10 ratio [2.2 × 10³ (1.8-3.4) vs. 0.3 × 10³ (0.2-0.5), P = 0.003] than in controls. Patients who developed unmasking TB-IRIS had higher median pre-ART levels of CRP [25 (8-47) vs. 6 (lower limit of detection, LLD-12) mg/l, P = 0.046] and interferon gamma (IFN-γ) [9.1 (4.4-24.7) vs. 0.9 (LLD-8.7) pg/ml, P = 0.032] than controls.

CONCLUSION

Patients with unmasking TB-IRIS had higher pre-ART levels of plasma IFN-γ and CRP, consistent with preexisting subclinical TB. Paradoxical TB-IRIS was associated with lower levels of biomarkers of monocyte and regulatory T-cell activity, and higher CRP.

The search for biomarkers of immune restoration disease associated with Mycobacterium tuberculosis in HIV patients beginning antiretroviral therapy

Immune restoration disease associated with Mycobacterium tuberculosis is a complication of antiretroviral therapy seen in a subset of HIV-1 patients soon after they commence antiretroviral therapy. It is characterized by a ‘paradoxical’ worsening of treated tuberculosis or an ‘unmasking’ of subclinical tuberculosis. As antiretroviral therapy becomes increasingly available in countries with a high prevalence of tuberculosis, this form of immune restoration disease will become more common. Here we summarize biomarkers that may illuminate immunopathogenesis and assist in diagnosis.

Potential role of statins for the management of immune reconstitution syndrome

It has become evident that while a robust inflammatory response plays a critical role in eradicating invading microbes, dysregulated immunity can be detrimental to the host if an optimal balance between the inflammatory and anti-inflammatory reactions is disrupted. Opportunistic infection-associated immune reconstitution syndrome is characterized by an aggressive inflammatory immune response and its management remains challenging and largely unknown. Statins, in addition to their lipid lower effects have anti-inflammatory attributes and there is precedence for the use of these agents as a therapeutic modality for autoimmune inflammatory disorders which have similar underlying pathogenesis as immune reconstitution syndrome. We hypothesize that statins may have a potential role for the management of immune reconstitution syndrome. Our proposal has biologic and translational implications for optimizing outcomes in patients with immune reconstitution syndrome.

Increased peripheral blood leukocyte subsets with regulatory phenotype in clinically stable long-term HIV-infected hemophilia patients on HAART may be beneficial and contribute to a decrease in autoimmunity

After initiation of highly-active antiretroviral therapy (HAART), long-term HIV-infected hemophilia patients have been shown to lose autoantibodies against CD4(+) peripheral blood leukocytes (PBL), suggesting that HAART induces autoimmunity-blocking mechanisms. We compared cytokine levels and subpopulations of lymphocytes and dendritic cells (DC) in the blood of 40 long-term HIV(+) patients with those of 13 long-term HIV(-) hemophilia patients; 23 HIV(+) patients had a detectable retroviral load. Cell subsets were determined using flow cytometry and cytokine levels were measured using ELISA. HIV(+) patients showed higher proportions of DC subpopulations with immunostimulatory phenotypes (p < 0.01), CD8(+) PBL (p < 0.001), and IL-2 (p < 0.001) and sIL-2R plasma levels (p = 0.002) than HIV(-) patients. They also exhibited increased proportions of T PBL with immunosuppressive phenotypes such as CD3(+)CD4(+)CD25(+)Foxp3(+) (p = 0.001), and CD3(+)CD8(+)CD28(-)Foxp3(+) PBL (p < 0.001), and a decreased IL-7R expression on CD3(+)CD8(+) PBL (p = 0.001) compared to HIV(-) patients. Frequencies of CD3(+)CD4(+)CD25(+) PBL producing IL-2, IL-4, IL-10, IL-12, and/or IFN-gamma, and of CD3(+)CD4(+)CD28(-) PBL secreting IL-2 and/or IL-4 were lower in HIV(+) than in HIV(-) patients (p <or= 0.02). Proportions of CD4(+) PBL coated with IgG, IgM, and C3d were similar in HIV(+) and HIV(-) patients (p = n.s.). However, the proportion of CD4(+)gp120(+) PBL was higher in HIV(+) patients (p = 0.002), and associated with low CD3(+)CD4(+)CD25(+)Foxp3(+) PBL (p = 0.012). We conclude that long-term HIV-infected hemophilia patients on HAART show an adaptive immune response, presumably against HIV, in the presence of upregulated immunosuppressive T PBL, downregulated cytokine-producing CD4(+) PBL, and downregulated IL-7R expression on CD8(+) PBL. Increased immunoregulatory T PBL might decrease autoimmunity, thereby contributing to immunological reconstitution and stabilization of long-term HIV-infected hemophilia patients on HAART.

Immune restoration diseases reflect diverse immunopathological mechanisms

Up to one in four patients infected with human immunodeficiency virus type 1 and given antiretroviral therapy (ART) experiences inflammatory or cellular proliferative disease associated with a preexisting opportunistic infection, which may be subclinical. These immune restoration diseases (IRD) appear to result from the restoration of immunocompetence. IRD associated with intracellular pathogens are characterized by cellular immune responses and/or granulomatous inflammation. Mycobacterial and cryptococcal IRD are attributed to a pathological overproduction of Th1 cytokines. Clinicopathological characteristics of IRD associated with viral infections suggest different pathogenic mechanisms. For example, IRD associated with varicella-zoster virus or JC polyomavirus infection correlate with a CD8 T-cell response in the central nervous system. Exacerbations or de novo presentations of hepatitis associated with hepatitis C virus (HCV) infection following ART may also reflect restoration of pathogen-specific immune responses as titers of HCV-reactive antibodies rise in parallel with liver enzymes and plasma markers of T-cell activation. Correlations between immunological parameters assessed in longitudinal sample sets and clinical presentations are required to illuminate the diverse immunological scenarios described collectively as IRD. Here we present salient clinical features and review progress toward understanding their pathogeneses.

Immunologic markers as predictors of tuberculosis-associated immune reconstitution inflammatory syndrome in HIV and tuberculosis coinfected persons in Thailand

This study analyzes immunologic markers to predict and diagnose tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) in HIV and TB coinfected adults who initiated antiretroviral therapy (ART) in Thailand. T helper 1 cytokines interleukin (IL)-2, IL-12, and interferon-gamma (IFN-gamma) levels in response to PPD and RD1 antigens were assessed prior to ART, at weeks 6, 12, and 24 of treatment, and at time of TB-IRIS. Of 126 subjects, 22 (17.5%) developed TB-IRIS; 14 (64%) subjects received steroid treatment and 3 (14%) received NSAIDs; none of the subjects died. Median interval between ART initiation and TB-IRIS development was 14 days. IFN-gamma, IL-2, and IL-12 responses did not differ between TB-IRIS and no TB-IRIS subjects (p > 0.05). More research into the immunopathogenesis of TB-IRIS and diagnostic potential of cytokine markers is warranted.

Polychromatic immunophenotypic characterization of T cell profiles among HIV-infected patients experiencing immune reconstitution inflammatory syndrome (IRIS)

Objective

To immunophenotype CD4⁺ and CD8⁺ T cell sub-populations in HIV-associated immune reconstitution inflammatory syndrome (IRIS).

Design

Nested case-control immunological study.

Methods

ART-naïve HIV-infected patients were prospectively observed for IRIS during the first 6 months of ART. Twenty-two IRIS cases and 22 ART-duration matched controls were sampled for T cell immunophenotyping.

Results

IRIS cases demonstrated significantly lower CD4 cell counts compared to controls (baseline: 79 versus 142, p = 0.02; enrollment: 183 versus 263, p = 0.05, respectively) with no differences in HIV RNA levels. Within CD4⁺T cells, cases exhibited more of an effector memory phenotype compared to controls (40.8 versus 27.0%, p = 0.20), while controls trended towards a central memory phenotype (43.8 versus 30.8%, p = 0.07). Within CD8⁺ T cells, controls exhibited more central memory (13.9 versus 7.81%, p = 0.01, respectively) and effector (13.2 versus 8.8%, p = 0.04, respectively) phenotypes compared to cases, whereas cases demonstrated more terminal effectors than controls (28.8 versus 15.1%, p = 0.05). Cases demonstrated increased activation of CD8⁺ T cell effector memory, terminal effector, and effector subsets than controls (p = 0.04, 0.02, and 0.02, respectively).

Conclusion

CD4⁺ and CD8⁺ T cell subset maturational phenotypes were heterogeneous among IRIS cases and controls. However, IRIS cases demonstrated significant increases in activation of CD8⁺ T cell effector subpopulations.

Type 1 helper T cells and FoxP3-positive T cells in HIV-tuberculosis-associated immune reconstitution inflammatory syndrome

RATIONALE

Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) induced by combination antiretroviral therapy (cART) has been attributed to dysregulated expansion of tuberculin PPD-specific IFN-gamma-secreting CD4(+) T cells.

OBJECTIVES

To investigate the role of type 1 helper T cell expansions and regulatory T cells in HIV-TB IRIS.

METHODS

Longitudinal and cross-sectional studies of Mycobacterium tuberculosis-specific IFN-gamma enzyme-linked immunospot responses and flow cytometric analysis of blood cells from a total of 129 adults with HIV-1-associated tuberculosis, 98 of whom were prescribed cART.

MEASUREMENTS AND MAIN RESULTS

In cross-sectional analysis the frequency of IFN-gamma-secreting T cells recognizing early secretory antigenic target (ESAT)-6, alpha-crystallins 1 and 2, and PPD of M. tuberculosis was higher in patients with TB-IRIS than in similar patients treated for both HIV-1 and tuberculosis who did not develop IRIS (non-IRIS; P <or= 0.03). The biggest difference was in the recognition of alpha-crystallin molecules: peptide mapping indicated a polyclonal response. Flow cytometric analysis indicated equal proportions of CD4(+) and CD8(+) cells positive for activation markers HLA-DR and CD71 in both patients with TB-IRIS and non-IRIS patients. The percentage of CD4(+) cells positive for FoxP3 (Forkhead box P3) was low in both groups (TB-IRIS, 5.3 +/- 4.5; non-IRIS, 2.46 +/- 2.46; P = 0.13). Eight weeks of longitudinal analysis of patients with tuberculosis who were starting cART showed dynamic changes in antigen-specific IFN-gamma-secreting T cells in both the TB-IRIS and non-IRIS groups: the only significant trend was an increased response to PPD in the TB-IRIS group (P = 0.041).

CONCLUSIONS

There is an association between helper T-cell type 1 expansions and TB-IRIS, but the occurrence of similar expansions in non-IRIS brings into question whether these are causal. The defect in immune regulation responsible for TB-IRIS remains to be fully elucidated.