Different profiles of immune reconstitution in children and adults with HIV-infection after highly active antiretroviral therapy

Modified quantitative approach for assessing peripheral blood TREC and KREC levels in immunodeficient patients

Introduction. The immune status is a multifaceted parameter quantitatively and qualitatively analyzing functional activity immune system state in immune organs as well as some non-specific mechanisms of antimicrobial protection. Peripheral blood level of T-receptor excision rings (TREC) and B-cell excision rings (KREC), respectively, can serve as surrogate markers of T- and B-cell maturation. Currently, the diagnostic kits available on the market have two significant disadvantages: i) the kits are aimed at diagnosing immunodeficiency conditions only in newborns and children, while keeping adult patients uncovered; ii) essentially, use solely single reference normalization gene for data normalization resulting in increased variability and decreased sensitivity of the assay data. The aim: to develop a highly sensitive method for laboratory assessment of the state of immunity in immunodeficient patients by using real-time PCR for assessing TREC and KREC level in children and adults. Materials and methods. There were used whole blood and dry blood spot samples obtained from newborns and adults, apparently healthy individuals as well as patients with verified PID and HIV-infection. A total of 2577 samples were examined. Commercial kits were used as comparison methods. Results. Multiplex PCR was carried out, analyzing the number of target molecules TREC and KREC, as well as fragments of the HPRT and RPP30 normalization genes analyzed with the developed series of plasmid calibrators. The established analytical range of TREC/KREC DNA measurements comprised 103 to 109 copies/mL. The accuracy of measurements on a tablet-type instrument (CFX) was 95.84%, on a rotary-type instrument (Rotor-Gene 3000) 95.11%, which corresponds to the standard indicator. The equivalence between the data obtained after assessing whole blood samples and dry blood drops was shown. The data analysis allowed to find out 100%-diagnostic specificity and sensitivity of the method proposed. Conclusion. The method developed by us allows to diagnose decline in T- and/or B-cell immunity in children and adults and can be used to detect TREC and KREC molecules both in peripheral whole blood samples and dry blood spots using Guthrie cards. Moreover, the uniform values of reference norms can be used regardless of the type of analyzed clinical material. The study data evidence about potential for effective use of multiplex PCR diagnostics both for complex primary testing/screening of newborns and assessing state of immunity to identify adult patients with PID and as a part of the diagnostic monitoring of patients with secondary immunodeficiencies, e.g., HIV infection.

Restoration of recent thymic emigrant CD4+ T cells is associated with sustained adherence to antiretroviral treatment in HIV-infected children

To evaluate the levels of recent thymic emigrant (RTE) CD4⁺ T cells in HIV-infected children and to explore the associations among their frequency, antiretroviral treatment (ART) adherence, and CD4⁺ T cell restoration. The group evaluated comprised 85 HIV-infected patients classified as subjects with moderate or severe immunosuppression or as those with no evidence of immunosuppression. To evaluate the association between the frequency of RTE CD4⁺ T cells and ART adherence, 23 of the 85 patients were evaluated at two different time points during a one-year follow-up period. Children with severe immunosuppression had lower frequencies of RTE CD4⁺ T cells compared with children without evidence of immunosuppression (P < .001). The frequency of RTE CD4⁺ T cells in children with a high rate of adherence was significantly higher (P < .05) than that observed among those with suboptimal adherence. The latter group presented with infectious intercurrences on admission that decreased after initiation of treatment along with improved CD4⁺ and RTE naïve CD4⁺ T cells counts. The adequate ART adherence is essential for immune reconstitution, which might be reflected by the levels of RTE CD4⁺ T cells.

Age is not just a number: Naive T cells increase their ability to persist in the circulation over time

The processes regulating peripheral naive T-cell numbers and clonal diversity remain poorly understood. Conceptually, homeostatic mechanisms must fall into the broad categories of neutral (simple random birth–death models), competition (regulation of cell numbers through quorum-sensing, perhaps via limiting shared resources), adaptation (involving cell-intrinsic changes in homeostatic fitness, defined as net growth rate over time), or selection (involving the loss or outgrowth of cell populations deriving from intercellular variation in fitness). There may also be stably maintained heterogeneity within the naive T-cell pool. To distinguish between these mechanisms, we confront very general models of these processes with an array of experimental data, both new and published. While reduced competition for homeostatic stimuli may impact cell survival or proliferation in neonates or under moderate to severe lymphopenia, we show that the only mechanism capable of explaining multiple, independent experimental studies of naive CD4⁺ and CD8⁺ T-cell homeostasis in mice from young adulthood into old age is one of adaptation, in which cells act independently and accrue a survival or proliferative advantage continuously with their post-thymic age. However, aged naive T cells may also be functionally impaired, and so the accumulation of older cells via ‘conditioning through experience’ may contribute to reduced immune responsiveness in the elderly.

The body maintains large populations of naive T cells, a type of white blood cell that is able to respond specifically to pathogens. This arsenal is essential for our capacity to fight novel infections throughout our lifespan, and their numbers remain quite stable despite a gradual decline in the production of new naive T cells as we age. However, the mechanisms that underlie this stability are not well understood. In this study, we address this problem by testing a variety of potential mechanisms, each framed as a mathematical model, against multiple datasets obtained from experiments performed in mice. Our analysis supports a mechanism by which naïve T cells gradually increase their ability to survive the longer they reside in the circulation. Paradoxically, however, naïve T cells may also lose their ability to respond effectively to infections as they age. Together, these processes may drive the accumulation of older, functionally impaired T cells, potentially at the expense of younger and more immunologically potent cells, as we age.

Supranormal thymic output up to 2 decades after HIV-1 infection

OBJECTIVES

AIDS is caused by CD4 T-cell depletion. Although combination antiretroviral therapy can restore blood T-cell numbers, the clonal diversity of the reconstituting cells, critical for immunocompetence, is not well defined.

METHODS

We performed an extensive analysis of parameters of thymic function in perinatally HIV-1-infected (n = 39) and control (n = 28) participants ranging from 13 to 23 years of age. CD4 T cells including naive (CD27 CD45RA) and recent thymic emigrant (RTE) (CD31/CD45RA) cells, were quantified by flow cytometry. Deep sequencing was used to examine T-cell receptor (TCR) sequence diversity in sorted RTE CD4 T cells.

RESULTS

Infected participants had reduced CD4 T-cell levels with predominant depletion of the memory subset and preservation of naive cells. RTE CD4 T-cell levels were normal in most infected individuals, and enhanced thymopoiesis was indicated by higher proportions of CD4 T cells containing TCR recombination excision circles. Memory CD4 T-cell depletion was highly associated with CD8 T-cell activation in HIV-1-infected persons and plasma interlekin-7 levels were correlated with naive CD4 T cells, suggesting activation-driven loss and compensatory enhancement of thymopoiesis. Deep sequencing of CD4 T-cell receptor sequences in well compensated infected persons demonstrated supranormal diversity, providing additional evidence of enhanced thymic output.

CONCLUSION

Despite up to two decades of infection, many individuals have remarkable thymic reserve to compensate for ongoing CD4 T-cell loss, although there is ongoing viral replication and immune activation despite combination antiretroviral therapy. The longer term sustainability of this physiology remains to be determined.

Thymic hyperplasia after chemotherapy in adults with mature B cell lymphoma and its influence on thymic output and CD4(+) T cells repopulation

To investigate the thymic regenerative potential in adults accepting chemotherapy for lymphoma. The dynamics of thymic activity in 54 adults from baseline to 12 mo post-chemotherapy was analyzed by assessing thymic structural changes with serial computed tomography (CT) scans, and correlating these with measurements of thymic output by concurrent analysis of single-joint (sj) T-cell receptor excision circles (sjTREC) and CD31⁺ recent thymic emigrants (RTE) in peripheral blood. Furthermore, the consequence of thymic renewal on peripheral CD4⁺ T cell recovery after chemotherapy was evaluated. Time-dependent changes of thymic size and thymic output assessed by both sjTREC levels and CD31⁺ RTE counts in peripheral blood were observed during and after chemotherapy. Enlargement of thymus over baseline following chemotherapy regarded as rebound thymic hyperplasia (TH) was identified in 20 patients aged 18−53 y (median 33 y). By general linear models repeated measure analysis, it was found that, patients with TH (n = 20) had a faster recovery of sjTREC levels and CD31⁺ RTE counts after chemotherapy than patients with comparable age, gender, diagnosis, disease stage, thymic volume and output function at baseline but without TH (n = 18) (p = 0.035, 0.047); besides, patients with TH had a faster repopulation of both naïve CD4⁺ T cell and natural regulatory CD4⁺ T cell subsets than those without TH (p = 0.042, 0.038). These data suggested that adult thymus retains the capacity of regeneration after chemotherapy, especially in young adults. The presence of TH could contribute to the renewal of thymopoiesis and the replenishment of peripheral CD4⁺ T cell pool following chemotherapy in adults.

Immune Reconstitution but Persistent Activation After 48 Weeks of Antiretroviral Therapy in Youth With Pre-Therapy CD4 >350 in ATN 061

BACKGROUND

Measures of immune outcomes in youth who initiate combination antiretroviral therapy (cART) early in HIV infection are limited.

DESIGN

Adolescent Trials Network 061 examined changes over 48 weeks of cART in T-cell subsets and markers of T-cell and macrophage activation in subjects with pre-therapy CD4 > 350 cells/mm. All subjects had optimal viral suppression from weeks 24 through 48.

METHODS

Subjects (n = 48) initiated cART with tenofovir/emtricitabine plus ritonavir-boosted atazanavir. Data were collected at baseline and weeks 12, 24, and 48. Trends were compared to uninfected controls.

RESULTS

Significant increases over 48 weeks were noted in all CD4 populations, including total, naive, central memory (CM), and effector memory RO (EM RO) and effector memory RA (EM RA), whereas numbers of CM and EM RO CD8 cells declined significantly. By week 48, CD4 naive cells were similar to controls, whereas CM CD4 cells remained significantly lower and EM RO and EM RA subsets were significantly higher. CD38 and HLA DR expression, both individually and when co-expressed, decreased over 48 weeks of cART on CD8 cells but remained significantly higher than controls at week 48. In contrast, markers of macrophage activation measured by sCD14 and sCD163 in plasma did not change with cART and were significantly higher than controls.

CONCLUSIONS

In youth initiating early cART, CD4 cell reconstitution is robust with decreases in CD8 cells. However, CD8 T-cell and macrophage activation persists at higher levels than uninfected controls.

Long-term effect of highly active antiretroviral therapy on immunologic features in children

BACKGROUND

Highly active antiretroviral therapy (HAART) has transformed human immunodeficiency virus infection (HIV) into a chronic condition. The effects of long-term HAART on the immune system activity of early infected children are not fully understood. Hence, the aim of this review is to investigate immune system recovery and residual alteration in HIV-infected children receiving HAART in high-income countries.

METHODS

A systematic review was performed by searches of PubMed and references of the relevant articles. Studies published between January 1, 2000 and April 1, 2014 and conducted in high-income countries reporting data on immunological features in HIV-infected children receiving HAART were included in this review.

RESULTS

Fifty-three articles were included in this review. Present knowledge on B-cell and T-cell function, immunoglobulin production, response to vaccine and innate immune system activity in HIV-infected children receiving HAART is discussed.

CONCLUSION

Starting therapy as soon as diagnosis is ascertained and monitoring vaccine response in children under HAART are the most important tools to safeguard immunological function in HIV-infected children.

Incomplete immune reconstitution despite virologic suppression in HIV-1 infected children and adolescents

OBJECTIVES

Some perinatally infected children do not regain normal CD4(+) T-cell counts despite suppression of HIV-1 plasma viremia by antiretroviral therapy (ART). The frequency, severity and significance of these discordant treatment responses remain unclear.

DESIGN

We examined the persistence of CD4(+) lymphocytopenia despite virologic suppression in 933 children (≥ 5 years of age) in the USA, Latin America and the Caribbean.

METHODS

CD4(+) T-cell trajectories were examined and Kaplan-Meier methods used to estimate median time to CD4(+) T-cell count at least 500 cells/μl.

RESULTS

After 1 year of virologic suppression, most (99%) children achieved a CD4(+) T-cell count of at least 200 cells/μl, but CD4(+) T-cell counts remained below 500 cells/μl after 1 and 2 years of virologic suppression in 14 and 8% of children, respectively. Median times to first CD4(+) T-cell count at least 500 cells/μl were 1.29, 0.78 and 0.46 years for children with less than 200, 200-349 and 350-499 cells/μl at the start of virologic suppression. New AIDS-defining events occurred in nine children, including four in the first 6 months of virologic suppression. Other infectious and HIV-related diagnoses occurred more frequently and across a wide range of CD4(+) cell counts.

CONCLUSION

ART improved CD4(+) cell counts in most children, but the time to CD4(+) cell count of at least 500 cells was highly dependent upon baseline immunological status. Some children did not reach a CD4(+) T-cell count of 500 cells/μl despite 2 years of virologic suppression. AIDS-defining events occurred in 1% of the population, including children in whom virologic suppression and improved CD4(+) T-cell counts were achieved.

Changes in cellular immune activation and memory T-cell subsets in HIV-infected Zambian children receiving HAART

BACKGROUND

Increased exposure to a broad array of pathogens in children residing in sub-Saharan Africa may lead to heightened immune activation and increased proportions of memory T cells. Changes in the size of these cellular subsets have implications for restoration of normal immune function after treatment with highly active antiretroviral therapy (HAART) and are not well characterized in young sub-Saharan African children.

METHODS

CD4⁺ and CD8⁺ T-cell subsets were measured by flow cytometry in 157 HIV-infected Zambian children before and at 3-month intervals during HAART for up to 30 months and in 34 control children at a single study visit.

RESULTS

Before HAART, HIV-infected children had higher levels of activated and effector memory (EM) CD4⁺ and CD8⁺ T cells, and lower levels of naive T cells and CD8⁺ T cells expressing IL-7Rα, compared with control children. The median duration of follow-up was 14.9 months (interquartile range, 6.4-23.2) among 120 HIV-infected children with at least 1 study follow-up visit. Levels of immune activation and EM CD4⁺ T cells declined within 6 months of HAART, but the percentages of EM CD4 T cells and effector CD8⁺ T cells remained elevated through 30 months of HAART. IL-7Rα-expressing CD8⁺ T cells increased with HAART, suggesting expansion of memory capacity.

CONCLUSIONS

HAART significantly reduced levels of immune activation and EM CD4⁺ T cells, and promoted reconstitution of naive T cells and IL-7Rα-expressing CD8⁺ T cells. However, persistently high levels of EM CD4⁺ T cells in HIV-infected children may reflect chronic perturbations in T-cell subset composition.

Immunology of pediatric HIV infection

Most infants born to human immunodeficiency virus (HIV)-infected women escape HIV infection. Infants evade infection despite an immature immune system and, in the case of breastfeeding, prolonged repetitive exposure. If infants become infected, the course of their infection and response to treatment differs dramatically depending upon the timing (in utero, intrapartum, or during breastfeeding) and potentially the route of their infection. Perinatally acquired HIV infection occurs during a critical window of immune development. HIV's perturbation of this dynamic process may account for the striking age-dependent differences in HIV disease progression. HIV infection also profoundly disrupts the maternal immune system upon which infants rely for protection and immune instruction. Therefore, it is not surprising that infants who escape HIV infection still suffer adverse effects. In this review, we highlight the unique aspects of pediatric HIV transmission and pathogenesis with a focus on mechanisms by which HIV infection during immune ontogeny may allow discovery of key elements for protection and control from HIV.

Predicting patterns of long-term CD4 reconstitution in HIV-infected children starting antiretroviral therapy in sub-Saharan Africa: a cohort-based modelling study

BACKGROUND

Long-term immune reconstitution on antiretroviral therapy (ART) has important implications for HIV-infected children, who increasingly survive into adulthood. Children's response to ART differs from adults', and better descriptive and predictive models of reconstitution are needed to guide policy and direct research. We present statistical models characterising, qualitatively and quantitatively, patterns of long-term CD4 recovery.

METHODS AND FINDINGS

CD4 counts every 12 wk over a median (interquartile range) of 4.0 (3.7, 4.4) y in 1,206 HIV-infected children, aged 0.4-17.6 y, starting ART in the Antiretroviral Research for Watoto trial (ISRCTN 24791884) were analysed in an exploratory analysis supplementary to the trial's pre-specified outcomes. Most (n = 914; 76%) children's CD4 counts rose quickly on ART to a constant age-corrected level. Using nonlinear mixed-effects models, higher long-term CD4 counts were predicted for children starting ART younger, and with higher CD4 counts (p<0.001). These results suggest that current World Health Organization-recommended CD4 thresholds for starting ART in children ≥5 y will result in lower CD4 counts in older children when they become adults, such that vertically infected children who remain ART-naïve beyond 10 y of age are unlikely ever to normalise CD4 count, regardless of CD4 count at ART initiation. CD4 profiles with four qualitatively distinct reconstitution patterns were seen in the remaining 292 (24%) children. Study limitations included incomplete viral load data, and that the uncertainty in allocating children to distinct reconstitution groups was not modelled.

CONCLUSIONS

Although younger ART-naïve children are at high risk of disease progression, they have good potential for achieving high CD4 counts on ART in later life provided ART is initiated following current World Health Organization (WHO), Paediatric European Network for Treatment of AIDS, or US Centers for Disease Control and Prevention guidelines. In contrast, to maximise CD4 reconstitution in treatment-naïve children >10 y, ART should ideally be considered even if there is a low risk of immediate disease progression. Further exploration of the immunological mechanisms for these CD4 recovery profiles should help guide management of paediatric HIV infection and optimise children's immunological development. Please see later in the article for the Editors' Summary.

Use of V(D)J recombination excision circles to identify T- and B-cell defects and to monitor the treatment in primary and acquired immunodeficiencies

T-cell receptor excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs) are circular DNA segments generated in T and B cells during their maturation in the thymus and bone marrow. These circularized DNA elements persist in the cells, are unable to replicate, and are diluted as a result of cell division, thus are considered markers of new lymphocyte output. The quantification of TRECs and KRECs, which can be reliably performed using singleplex or duplex real-time quantitative PCR, provides novel information in the management of T- and B-cell immunity-related diseases. In primary immunodeficiencies, when combined with flow cytometric analysis of T- and B-cell subpopulations, the measure of TRECs and KRECs has contributed to an improved characterization of the diseases, to the identification of patients’ subgroups, and to the monitoring of stem cell transplantation and enzyme replacement therapy. For the same diseases, the TREC and KREC assays, introduced in the newborn screening program, allow early disease identification and may lead to discovery of new genetic defects. TREC and KREC levels can also been used as a surrogate marker of lymphocyte output in acquired immunodeficiencies. The low number of TRECs, which has in fact been extensively documented in untreated HIV-infected subjects, has been shown to increase following antiretroviral therapy. Differently, KREC number, which is in the normal range in these patients, has been shown to decrease following long-lasting therapy. Whether changes of KREC levels have relevance in the biology and in the clinical aspects of primary and acquired immunodeficiencies remains to be firmly established.

T-cell subset distribution in HIV-1-infected patients after 12 years of treatment-induced viremic suppression

OBJECTIVE

Residual immune activation and skewed T cell maturation may contribute to excess comorbidity and mortality in successfully treated HIV-infected patients, and long-term effects of combination antiretroviral therapy (cART) on immune reconstitution remain a debated issue. Quantitative T cell reconstitution and activation and its association with residual viremia in patients with 12 years of viremic suppression were investigated.

DESIGN

Blood samples collected cross-sectionally from 71 HIV-infected patients with cART-induced viremic suppression through 12 years were compared with samples from 16 healthy controls.

METHODS

Several different subsets of naive, memory, and activated T cells were analyzed in fresh whole blood by 6-color flowcytometry, and ultrasensitive quantification of HIV RNA was performed.

RESULTS

HIV-infected patients had lower absolute and relative CD4 T cell counts and higher absolute and relative CD8 T cell counts than controls. HIV-infected patients had lower concentrations of naive CD4 cells than controls, but proportions were similar. HIV-infected patients had higher concentrations of CD8 T cells than controls in all the examined subsets but only a higher proportion of CD8 cells in the intermediately differentiated and activated subsets. Residual viremia did not correlate to proportions of naive CD4, CD4 recent thymic emigrants, or activated CD8 T cells.

CONCLUSIONS

This study demonstrated some degree of T cell imbalance even after 12 years of successful cART. Large longitudinal studies are needed to establish whether these discrete changes have clinical relevance.

Detectable viral load aggravates immunosenescence features of CD8 T-cell subsets in vertically HIV-infected children

BACKGROUND

CD8 T cells are crucial in the immune responses against HIV infection, but HIV-infected adults suffer a naive CD8 T-cell depletion and accelerated senescence caused by chronic antigen stimulation. Although HIV-infected children preserve a better immune reconstitution capacity their CD8 responses are defective. We wanted to know, whether HIV vertical transmission produces a premature aging of the CD8 population due to antigen exposition to HIV from birth and persistent chronic activation.

METHODS

We conducted a multicentre cross-sectional study that compared vertically HIV-infected children with detectable (viremic) or undetectable (aviremic) viral load and age-matched healthy children. Using multiparameter flow cytometry, we studied within the CD8 population the frequencies of naive, memory, effector memory (effector memory), and TemRA subsets and measured markers of senescence, activation, and proliferation in these cells.

RESULTS

We found that naive subset in viremic children was markedly decreased and had a replicative senescence phenotype. Furthermore, viremic children showed increased frequencies of memory, TEM and TemRA CD8 T cells, with a more activated and replicative senescence phenotype. We found that HIV-infected children with undetectable viral load have an increased senescence in memory and effector CD8 T cells, but the frequencies and phenotype of the CD8 subsets analyzed are comparable to healthy children.

CONCLUSIONS

[corrected] Our study shows that CD8 T cells of HIV-infected children have a more senescent phenotype when compared with age-matched healthy children. Interestingly enough, our results support the importance of maintaining undetectable viral load in HIV-infected children to avoid the premature ageing and dysfunction of CD8 T cells.

Impact of CD4 T cell count on the outcome of planned treatment interruptions in early-treated human immunodeficiency virus-infected children

Early highly active antiretroviral therapy is recommended in all vertically human immunodeficiency virus (HIV)-infected infants. We describe the long-term immunologic outcome after planned treatment interruption (PTI) in 7 children diagnosed and treated during acute HIV infection (age <12 weeks). Children had remained a median of 57 months off treatment, 3 of them indefinitely. The 2 patients with the lowest nadir CD4% reinitiated highly active antiretroviral therapy because of a CD4 cell decline of <20%; 2 children resumed treatment because of clinical progression and parents' wishes. All patients experienced a decrease in CD4% after PTI, which particularly affected the naive subpopulation. The interferon-γ response against HIV-p24 antigen directly correlated with nadir CD4%. Our results suggest that early treatment in HIV-infected infants increases their potential to safely control viral replication after PTI for long periods.

Immune Reconstitution Syndrome in HIV-1 infected children - a study from India

OBJECTIVE

To determine incidence of Immune Reconstitutional Syndrome (IRIS) in HIV infected children and also to determine risk factors associated with it.

METHODS

Thirty-seven HIV infected children who were started on Antiretroviral therapy (ART) in past 2 years were included in the study. Statistical Analysis was done using Chi Square test.

RESULTS

Seven patients (18.9%) had IRIS at a mean interval of 1.7 ± 0.8 months. Two patients (28.6%) had tuberculosis (TB), 2 patient (28.6%) had herpes zoster and 1 patient (14.3%) each had pneumonia, toxoplasmosis and esophageal candidiasis. There was no significant difference as per age (p = 0.8), WHO Stage of disease (p = 0.93), Sex (0.45), type of antiretroviral regime (p = 0.38) and severity of immune suppression (0.98). It was found that patients with opportunistic infections (OIs) before treatment would have increased incidence of IRIS (p = 0.05). The mean OIs/year prior to treatment in patients with IRIS was 2.6 ± 1.4 vs. 1.7 ± 1.2.

CONCLUSIONS

Incidence of IRIS in HIV infected children in Mumbai is 18.9%. Patients with OIs before treatment with ART have an increased incidence of IRIS. Clinical stage of disease or degree of immune suppression prior to treatment had no effect on incidence of IRIS.

Characterization of quantitative and functional innate immune parameters in HIV-1-infected Colombian children receiving stable highly active antiretroviral therapy

BACKGROUND

The immunological benefits of highly active antiretroviral therapy (HAART) in HIV-1-infected children include reconstitution of CD4+ T-cell count and functional activity. The effect of HAART on innate immune cells has not been well established.

AIM

To characterize innate immune responses in HAART-treated HIV-1-infected children.

PATIENTS AND METHODS

23 HIV-1-infected children on stable HAART and 23 uninfected children were evaluated. The frequency of innate immune cells in peripheral blood was determined by flow cytometry and functional activity was evaluated using Toll-like receptor agonists.

RESULTS

Compared with uninfected children, HAART-treated HIV-1-infected children exhibited a significant decrease in the frequency of plasmacytoid dendritic cells and natural killer and T-cell receptor (TCR)-invariant CD1d-restricted T cells. This deficiency of innate immune cells was observed mainly in children with detectable viral load. We also compared the magnitude of the quantitative restoration of those cells comparing HIV-1-infected children with HIV-1-infected adults and found a partial effect of HAART on immune restoration that was independent of age. In both pediatric and adult subjects Toll-like receptor agonists induced expression of costimulatory molecules and production of proinflammatory cytokines by dendritic cells. Peripheral blood mononuclear cells of HIV-1-infected children produced significantly reduced amounts of interferon-alpha compared with uninfected children.

CONCLUSIONS

HAART administration to HIV-1-infected children does not lead to a complete increase of circulating innate immune cells, particularly in patients with incomplete suppression of HIV.

CD4 cell response before and after HAART initiation according to viral load and growth indicators in HIV-1-infected children in Abidjan, Côte d'Ivoire

OBJECTIVE

To analyze the determinants of CD4 change in children during 3 periods: before highly active antiretroviral therapy (HAART), during the first year after HAART initiation, and past 1 year after HAART initiation.

METHODS

One hundred seventy-seven children enrolled in a prospective cohort in Abidjan received HAART during a mean follow-up of 30 months. A linear mixed-effects model was used for the first period, a mixed-effects piecewise model for the second period, and an asymptotic mixed-effects model for long-term CD4 dynamics.

RESULTS

Before HAART initiation, CD4 percentage decreased along time [beta = -0.59 (-0.92 to -0.26)] was positively associated with body mass index for age [beta = 0.47 (0.22 to 0.72)] and negatively associated with viral load [beta = -1.01 (-1.90 to -0.13)]. During the first year of treatment, the CD4 decrease reverted to a steep increase that was negatively associated with age at HAART initiation [beta = -0.24 (-0.4 to -0.07)] and with the mean viral load under HAART [beta = -1.51 (-2.21 to -0.81)]. The long-term CD4 percentage was also negatively associated with the mean viral load under HAART [beta = -4.97 (-6.22 to -3.72)] and age at HAART initiation [beta = -0.82 (-1.12 to -0.51)].

CONCLUSIONS

Before HAART initiation, the CD4 cell percentage was associated with growth indicators whereas, after HAART, an early increase and a long-term plateau were negatively associated with the viral load and age at HAART initiation.

Successful Rescue Therapy with a Darunavir/Ritonavir and Etravirine Antiretroviral Regimen in a Child with Vertically Acquired Multidrug-Resistant HIV-1

An increasing prevalence of antiretroviral therapy (ART) resistance in ART-experienced and ART-naive pregnant women has been reported. Some studies suggest that antiretroviral drug-resistant viruses might have decreased replication capacity and transmissibility. However, cases of perinatal transmission of multidrug-resistant HIV type-1 (HIV-1) have been described. Here, we report the case of one child with vertically-acquired multidrug-resistant HIV-1 and the outcome of a rescue therapy with a darunavir/ritonavir- and etravirine-containing antiretroviral regimen. During the 15 months of therapy, the child showed clinical improvement, including no side effects, persistent suppression of viral replication and a great increase in CD4+ T-cell count. Paediatric HIV specialists should be prepared to manage a small, but increasing, number of babies with a ‘nightmare’ multid-rug-resistant virus with no available treatment options. The use of experimental agents might become a compelling issue in vertically HIV-infected children born in the era of highly active ART.