Correlation of CD8 lymphocyte activation with cellular viremia and plasma HIV RNA levels in asymptomatic patients infected by human immunodeficiency virus type 1

CRISPR/Cas9-Mediated Insertion of HIV Long Terminal Repeat within BACH2 Promotes Expansion of T Regulatory-like Cells

One key barrier to curative therapies for HIV is the limited understanding of HIV persistence. HIV provirus integration sites (ISs) within BACH2 are common, and almost all sites mapped to date are located upstream of the start codon in the same transcriptional orientation as the gene. These unique features suggest the possibility of insertional mutagenesis at this location. Using CRISPR/Cas9-based homology-directed repair in primary human CD4+ T cells, we directly modeled the effects of HIV integration within BACH2 Integration of the HIV long terminal repeat (LTR) and major splice donor increased BACH2 mRNA and protein levels, altered gene expression, and promoted selective outgrowth of an activated, proliferative, and T regulatory-like cell population. In contrast, introduction of the HIV-LTR alone or an HIV-LTR-major splice donor construct into STAT5B, a second common HIV IS, had no functional impact. Thus, HIV LTR-driven BACH2 expression modulates T cell programming and leads to cellular outgrowth and unique phenotypic changes, findings that support a direct role for IS-dependent HIV-1 persistence.

Short Communication: Extremely Severe CD4 Lymphopenia During HIV-1 Primary Infection

We report the case of a patient with a very profound CD4 T cell lymphopenia <20 cells/mm³ in the context of a primary HIV-1 infection, associated with both delayed HIV-specific antibody and CD8 T cell responses. A long-term immune reconstitution was observed after immediate initiation of antiretroviral therapy.

Forkhead box protein 3(+) regulatory T cells and Helios(+) subset in perinatally acquired HIV

Forkhead box protein 3 (FoxP3)(+) regulatory T cells (Tregs ) are important not only in regulating the development of autoimmune conditions, but also in chronic infectious diseases. Given their cardinal function in suppressing immune activation, research has focused upon whether they play a detrimental role in chronic infections, particularly HIV. While the role of Tregs in HIV has been investigated intensively, it remains an unresolved topic. However, it is generally accepted that Tregs are susceptible to HIV infection and are preferentially preserved over conventional CD4(+) T cells. It is unknown whether the peripheral-induced or the thymic-derived Tregs are more susceptible to HIV cytotoxicity. It has been recognized that Tregs can be segregated into two subsets based on Helios expression, with the vast majority being Helios(+) . This study examines the impact of HIV infection on total Tregs and their Helios subsets in a perinatal-acquired HIV-infected paediatric population. The finding indicates a selective expansion or survival of Tregs in association with CD4 depletion and increased viraemia. The Helios(+) and Helios(-) subsets within Tregs appear to be equally affected. However, the Helios(+) Tregs seem to be more preserved in patients with low CD4(+)  ≤ 25% and detectable plasma HIV RNA >20 copies/ml. In this group, the frequencies of Tregs are increased, but their numbers appear insufficient to restrain immune activation. In conclusion, our findings suggest that both Helios subsets of Tregs are susceptible to HIV infection and are preferentially preserved compared to conventional CD4(+) T cells.

Modulating DNA methylation in activated CD8+ T cells inhibits regulatory T cell-induced binding of Foxp3 to the CD8+ T Cell IL-2 promoter

We have previously demonstrated that CD4(+)CD25(+) regulatory T cells (Tregs) activated during the course of feline immunodeficiency virus (FIV) infection suppress CD8(+) CTL function in a TGF-β-dependent fashion, inhibiting IFN-γ and IL-2 production and inducing G1 cell-cycle arrest. In this article, we describe the molecular events occurring at the IL-2 promoter leading to suppression of IL-2 production. These experiments demonstrate that Foxp3 induced by lentivirus-activated Tregs in the CD8(+) target cells binds to the IL-2 promoter, actively repressing IL-2 transcription. We further demonstrate that the chronic activation of CD8(+) T cells during FIV infection results in chromatin remodeling at the IL-2 promoter, specifically, demethylation of CpG residues. These DNA modifications occur during active transcription and translation of IL-2; however, these changes render the IL-2 promoter permissive to Foxp3-induced transcriptional repression. These data help explain, in part, the seemingly paradoxical observations that CD8(+) T cells displaying an activation phenotype exhibit altered antiviral function. Further, we demonstrate that blocking demethylation of CpG residues at the IL-2 promoter inhibits Foxp3 binding, suggesting a potential mechanism for rescue and/or reactivation of CD8(+) T cells. Using the FIV model for lentiviral persistence, these studies provide a framework for understanding how immune activation combined with Treg-mediated suppression may affect CD8(+) T cell IL-2 transcription, maturation, and antiviral function.

Immune activation and viral replication after vaccination with an influenza A H1N1 2009 vaccine in HIV-infected children receiving antiretroviral therapy

Immunization with a pandemic influenza A H1N1 2009 was recommended for HIV-infected patients. However, there is limited information concerning the impact of immunization with this vaccine on immune activation and HIV viral replication. In this study, 45 HIV-infected children and adolescents receiving antiretroviral therapy were immunized with a 2-dose series of nonadjuvated monovalent influenza A H1N1 2009 vaccine upon enrollment and approximately 1 month later. Immunogenicity was determined by haemagglutination inhibition assay. The level of immune activation was determined by identification of CD38 and HLA-DR on CD8+ T cells. Patients were divided into 2 groups which include patients who had an undetectable HIV viral load (HIV detectable group) and patients who show virological failure (HIV nondetectable group). The results showed seroconversion rate of 55.2% in HIV nondetectable group, whereas 31.3% was found in HIV detectable group. Both groups of patients showed no major increase in immune activation after immunization. Interestingly, a decrease in the frequency of CD8+ T cells that coexpressed CD38 and HLA-DR was observed after immunization in both groups of patients. We suggested that immunization with influenza A H1N1 2009 vaccine can induce immune response to the pandemic virus without major impact on HIV viral replication and immune activation.

CD4+FOXP3+ Regulatory T-Cell Subsets in Human Immunodeficiency Virus Infection

The role of CD4+FOXP3+ regulatory T cells (Treg) in human immunodeficiency virus (HIV) infection has been an area of intensive investigation and remains a matter of ardent debate. Investigation and interpretation suffered from uncertainties concerning Treg quantification. Firstly, Treg quantification and function in HIV infection remain controversial in part because of the lack of reliable and specific markers to identify human Tregs. Secondly, analyzing Treg percentages or absolute numbers led to apparent discrepancies that are now solved: it is now commonly accepted that Treg are targets of HIV infection, but are preferentially preserved compared to conventional CD4 T cells. Moreover, the duality of immune defects associated to HIV infection, i.e., low grade chronic inflammation and defects in HIV-specific responses also casts doubts on the potential impact of Treg on HIV infection. Tregs may be beneficial or/and detrimental to the control of HIV infection by suppressing chronic inflammation or HIV-specific responses respectively. Indeed both effects of Treg suppression have been described in HIV infection. The discovery in recent years of the existence of phenotypically and functionally distinct human CD4+FOXP3+ Treg subsets may provide a unique opportunity to reconcile these contrasting results. It is tempting to speculate that different Treg subsets exert these different suppressive effects. This review summarizes available data concerning Treg fate during HIV infection when considering Treg globally or as subsets. We discuss how the identification of naïve and effector Treg subsets modulates our understanding of Treg biology during HIV infection and the potential impact of HIV infection on mechanisms governing peripheral differentiation of adaptive Tregs.

CD8+ clonality is associated with prolonged acute plasma viremia and altered mRNA cytokine profiles during the course of feline immunodeficiency virus infection

Acute lentiviral infection is characterized by early CD8(+) cytotoxic T cell (CTL) activity and a subsequent decline in plasma viremia. However, CD8(+) lymphocytes fail to eliminate the virus and a progressive T cell immune dysfunction develops during the course of chronic lentiviral infection. To further define this CD8(+) immune dysfunction we utilized PARR (PCR for antigen receptor rearrangements), a technique which measures clonally expanded lymphocyte populations by comparison of highly conserved T cell receptor (TCR) regions to identify the prevalence of clonal CD8(+) T cells following FIV infection. We then compared phenotype, mRNA profiles, CD8(+) proliferation and plasma viremia during acute and chronic infection for PARR positive (PARR(+)) and PARR negative (PARR(-)) Feline Immunodeficiency Virus (FIV) infected cats. We demonstrated that approximately forty percent of the FIV(+) cats examined exhibit CD8(+) clonality compared to none of the FIV(-) control cats. There were no phenotypic differences between PARR(+) and PARR(-) CD8(+) lymphocytes from FIV(+) cats but retrospective analysis of plasma viremia over the course of infection revealed a delayed peak in plasma viremia and a decline in lymphocyte counts were observed in the PARR(+) group during acute infection. CD8(+) lymphocytes isolated from chronically infected PARR(-) cats exhibited significantly higher mRNA expression of IFN-γ and IL-2 following mitogenic stimulation when compared to PARR(+) CD8(+) lymphocytes. These data suggest that clonal CD8(+) expansion may be related to impaired control of acute viremia and less effective CD8(+) anti-viral function. Using PARR to assess changes in CD8(+) clonality during the progression from acute to chronic FIV infection may help to better characterize the factors which contribute to CD8(+) anergy and lentiviral persistence.

Study of T cell subsets and IL-7 protein expression in HIV-1-infected patients after 7 years HAART

Objective

To study the changes in T cell subsets and IL-7 in HIV-1-infected patients after seven years of highly active antiretroviral therapy (HAART).

Methods

Seventy-five individuals were included in this study (25 with effective HAART, 18 with ineffective HAART, 17 untreated HIV+ patients, and 15 volunteers in the HIV negative control group). The counts of CD4⁺, CD8⁺, CD8/CD38⁺, and CD8/HLADR⁺ T cells as well as the IL-7 protein expression was measured at 5 time points during a period of seven years in patients starting HAART (baseline) and in the HIV negative control group. The expression of CD127 on CD3⁺ T cells was measured by flow cytometry at a single time point (after 7 years) in patients with HAART and was compared with untreated HIV+ patients and the HIV negative control group.

Results

At baseline CD4⁺ T cell counts of HIV-1-infected patients were lower than that in the control group (p < 0.01), whereas the CD8⁺, CD8/HLADR⁺ and CD8/CD38⁺ T cell counts were higher than those in the control group (p <0.01). After seven years of effective HAART, the CD4⁺ T cell counts had increased and the CD8⁺ T cell count had decreased, although not to the normal levels (p < 0.05). Both the CD8/HLADR⁺ and CD8/CD38⁺ T cell counts had gradually approached those of the control group (p > 0.05). In the ineffective HAART group, the CD8/CD38⁺ T cell count had not decreased significantly, and CD8/HLADR⁺ T cell count gradually decreased. Before treatment, IL-7 serum levels of patients were significantly higher than that in the control group (p < 0.01). After seven years of effective HAART, IL-7 levels had gradually decreased, but were still higher than in the control group (p < 0.01). The CD127 expression on CD3⁺ CD8⁺ T cells in effective HAART patients was higher than in untreated HIV+ patients (p < 0.05), but was lower than that in the control group (p < 0.05). CD127 expression on CD3⁺ CD4+ T cells was not significantly different among the control group, untreated HIV+ patients and effective HAART group.

Conclusion

After seven years of effective HAART, the quantity and capacity of T cell subsets and IL-7 in HIV-1-infected patients had been partially restored, and the abnormal immune activation has significantly diminished.

Differences in HIV burden and immune activation within the gut of HIV-positive patients receiving suppressive antiretroviral therapy

BACKGROUND

The gut is a major reservoir for human immunodeficiency virus (HIV) in patients receiving antiretroviral therapy (ART). We hypothesized that distinct immune environments within the gut may support varying levels of HIV.

METHODS

In 8 HIV-1-positive adults who were receiving ART and had CD4(+) T cell counts of >200 cells/μL and plasma viral loads of <40 copies/mL, levels of HIV and T cell activation were measured in blood samples and endoscopic biopsy specimens from the duodenum, ileum, ascending colon, and rectum.

RESULTS

HIV DNA and RNA levels per CD4(+) T cell were higher in all 4 gut sites compared with those in the blood. HIV DNA levels increased from the duodenum to the rectum, whereas the median HIV RNA level peaked in the ileum. HIV DNA levels correlated positively with T cell activation markers in peripheral blood mononuclear cells (PBMCs) but negatively with T cell activation markers in the gut. Multiply spliced RNA was infrequently detected in gut, and ratios of unspliced RNA to DNA were lower in the colon and rectum than in PBMCs, which reflects paradoxically low HIV transcription, given the higher level of T cell activation in the gut.

CONCLUSIONS

HIV DNA and RNA are both concentrated in the gut, but the inverse relationship between HIV DNA levels and T cell activation in the gut and the paradoxically low levels of HIV expression in the large bowel suggest that different processes drive HIV persistence in the blood and gut.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00884793 (PLUS1).

Dynamic correlation between CTL response and viral load in primary human immunodeficiency virus-1 infected Koreans

Background

HIV-1 specific cytotoxic T lymphocytes (CTLs) have an important role as antiviral effector cells for controlling HIV-1 infection.

Methods

To investigate CTL response during the early stage of HIV infection, we measured immunity-related factors including CD4⁺ T cell counts, CD8⁺ T cell counts, HIV-1 RNA viral loads and IFN-γ secretion according to CTL response in 78 selected primary HIV-1-infected Koreans.

Results

The CTL response was strongly induced by HIV-1 specific Gag and Nef peptides (p = 0.016) compared with induction by Tat or Env peptides. These results suggest that the major antiviral factors inducing strong HIV-specific CTL responses are associated with the Gag and Nef viral regions in primary HIV-1 infected Koreans. The relationship between viral load and CTL response showed varying correlations with time following HIV infection. CTL response was inversely correlated with viral loads at preseroconversion stage I (r = -0.224 to -0.33) and changed to a positive correlation at the preseroconversion stage II (r = 0.132 to 0.854). Finally, it changed to an inverse correlation again after seroconversion until a viral set point was established on serological profiling (r = -0.195 to -0.407).

Conclusions

These findings demonstrate a dynamic correlation between viral load and subsequent CTL responses during early HIV infection.

Infection of CD8+CD45RO+ memory T-cells by HIV-1 and their proliferative response

CD8+ T-cells are involved in controlling HIV-1 infection by eliminating infected cells and secreting soluble factors that inhibit viral replication. To investigate the mechanism and significance of infection of CD8+ T-cells by HIV-1 in vitro, we examined the susceptibility of these cells and their subsets to infection. CD8+ T-cells supported greater levels of replication with T-cell tropic strains of HIV-1, though viral production was lower than that observed in CD4+ T-cells. CD8+ T-cell infection was found to be productive through ELISA, RT-PCR and flow cytometric analyses. In addition, the CD8+CD45RO+ memory T-cell population supported higher levels of HIV-1 replication than CD8+CD45RA+ naïve T-cells. However, infection of CD8+CD45RO+ T-cells did not affect their proliferative response to the majority of mitogens tested. We conclude, with numerous lines of evidence detecting and measuring infection of CD8+ T-cells and their subsets, that this cellular target and potential reservoir may be central to HIV-1 pathogenesis.

The role of compartment penetration in PI-monotherapy: the Atazanavir-Ritonavir Monomaintenance (ATARITMO) Trial

OBJECTIVES

To limit exposure to anti-HIV drugs and minimize risk of long-term side effects, studies have looked at the possibility of simplified maintenance strategies. Ritonavir-boosted protease-inhibitor (PI)-monotherapies are an attractive alternative, but limited compartmental penetration of PI remains a concern.

DESIGN

Non-comparative 24-week pilot study.

METHOD

Ritonavir-boosted atazanavir (ATV/r) monotherapy administered to fully suppressed patients (>3 month HIV RNA < 50 copies/ml). Plasma was obtained every 4 weeks and cerebrospinal fluid (CSF) and semen at W24.

RESULTS

Two patients (7%) failed ATV/r monotherapy. One patient was subsequently identified as a protocol violator since he had a previous history of treatment failure under indinavir. The second patient deliberately decided to stop treatment after W20. Excluding failing patients, individual measurements of HIV RNA in patients having occasional viral 'blips' was found in five patients. At W24, 3/20 patients had elevated viral loads in CSF (HIV RNA > 100 copies/ml), and 2/15 in semen, despite viral suppression in plasma (< 50 copies/ml). Samples with elevated HIV RNA (> 500 copies/ml) in CSF were all wild type. The mean ATV drug concentration ratio (CSF/blood, n = 22) was 0.9%. Indicators of altered immune activation (CD8CD38 C-reactive protein) remained unchanged.

CONCLUSION

This study supports previous results indicating the potential use of PI-based mono-maintenance therapies. However, our results in CSF cautions against the uncontrolled use of PI-based monotherapies.

Association between HIV Type 1-specific T cell responses and CD4+ T cell counts or CD4+:CD8+ T cell ratios in HIV Type 1 subtype B infection in China

CD4+ T cell counts and CD4+:CD8+ T cell ratios represent key determinants of HIV disease progression and infectivity. However, the relationship between the HIV-1-specific cytotoxic T lymphocyte (CTL) response and these determinants has not been elucidated for all HIV-1B and HIV-1C proteins. In the present study, virusspecific T cell responses to HIV-1B and HIV-1C proteins were analyzed with interferon gamma (IFN-gamma) enzyme- linked immunospot (ELISpot) assays using synthetic overlapping peptides corresponding to naturally occurring HIV-1B and HIV-1C consensus sequences. For Gag/Gag p24/Gag p17, a correlation between T cell responses and CD4+ T cell count in HIV-1 clade B and clade C was seen: elevated T cell response resulted in higher CD4+ T cell production. A statistically significant correlation between the Pol-specific T cell response and CD4+ T cell counts was also found in HIV-1 subtype C. For all HIV-1B and HIV-1C proteins, a correlation between the HIV-1-specific T cell response and CD4+:CD8+ T cell ratios was found for Tat and Pol proteins. CD4+ T cell counts in patients with Tat and/or Rev T cell response were higher than in patients without Tat and/or Rev T cell response. We suggest that this correlation within HIV-1B and HIV-1C Gag p24/Gag p17 responses makes the Gag p24/Gag p17 region a potential vaccine candidate and that HIV-1-specific CTL epitopes toward Pol are important in controlling HIV-1 infection; we emphasize that future vaccination strategies should include these early antigens, Tat and Rev.

Correlation of T-lymphocyte subpopulations with immunological markers in HIV-1-infected Indian patients

Progressive HIV disease is characterized by CD4 T cell decline and activation of the immune system. We aimed to study the quantitative alterations in the naive (CD45RA+CD62L+), memory/effector (CD45RO+) and activated (HLA-DR+CD38+) T-lymphocyte subpopulations in antiretroviral treatment naive, HIV-1 infected Indian patients by three-color multi-parametric flow cytometry. The association of different CD4+ and CD8+ T cell subsets with the immunological markers- CD4+ and CD8+ T cell percentages was examined by calculating the partial correlation coefficients. We also observed significant differences in the expression of different CD4+ and CD8+ T-cell subsets among the two groups of patients formed using the median CD4+ T cell percentage value (15%) of the study population. The correlations of different CD4+ and CD8+ T cell subsets reflected the quantitative alterations in the T-lymphocyte subpopulations and activation of the immune system during HIV-infection. The study outcome also emphasizes the significance of the CD38+CD8+ T-lymphocyte subset as a prognostic marker for HIV management and ART monitoring in resource-limited settings of developing countries like India.

Assessment of CD8 T cell immune activation markers to monitor response to antiretroviral therapy among HIV-1 infected patients in Côte d'Ivoire

Because of the paucity of plasma HIV RNA viral load (VL) tests in resource-poor settings, the CD4(+) T cell count is often used as the sole laboratory marker to evaluate the effectiveness of antiretroviral therapy (ART) in HIV-infected patients. In untreated patients, the level of activated T cells is positively correlated with VL and represents a prognostic marker of HIV infection. However, little is known about its value to predict early drug failure, taking into account the relatively high non-specific immune activation background observed in many resource-limited tropical countries. We assessed the use of immune activation markers (expression of CD38 and/or human leucocyte antigen-DR on CD8(+) lymphocytes) to predict virological response to ART in a cohort of HIV-1 infected patients in Abidjan, Côte d'Ivoire. Correlations between VL, absolute CD4(+) T cell counts and immune activation levels were examined in 111 HIV patient samples at baseline and after 6 and 12 months of therapy. The percentage of CD38(+) CD8(+) T cells appeared to be the best correlate of VL. In contrast, changes in CD4(+) T cell counts provided a poor correlate of virological response to ART. Unfortunately, CD38(+) CD8(+) percentages lacked specificity for the determination of early virological drug failure and did not appear to be reliable surrogates of RNA viral load. CD38(+) CD8(+) T cell percentages may, rather, provide a sensitive estimate of the overall immune recovery, and be a useful extra laboratory parameter to CD4 counts that would contribute to improve the clinical management of HIV-infected people when VL testing facilities are lacking.

[Changes in CD4+ and CD8+ T-cell subsets in HIV-infected children differently correlate with viral replication and thymic function]

BACKGROUND AND OBJECTIVE

We intended to study the relationship between T-cell subsets with plasmatic detectable viral load (VL) and T-receptor excision circles (TREC).

PATIENTS AND METHOD

Twenty HIV-infected children on highly active antiretroviral therapy (HAART) were recruited in a 1-year longitudinal retrospective study. We analyzed the relationship between changes in peripheral blood T-cell subsets, VL and TREC markers by lineal regression.

RESULTS

Memory and activated CD4+ T-cells increases had a negative association with log10 TRECs increases. However, naive CD4+ T-cells increases had a positive association with log10 TRECs increases. In contrast, memory, activated and effector CD8+ T-cells increases positively correlated with log10 VL increases. On the other hand, naive CD8+ T-cells increases had a negative association with log10 VL increases.

CONCLUSIONS

CD4+ and CD8+ T-cells subsets change in a different way as a response to the changes produced by HAART in HIV vertically infected children. CD4+ T-cells are more dependent on thymic function and CD8+ T-cells are more dependent on viral replication. Thus, the decline in cellular activation would allow the production of more naive T-cells by the thymus.

CD8+ T cells specific for EBV, cytomegalovirus, and influenza virus are activated during primary HIV infection

Primary viral infections, including primary HIV infection, trigger intense activation of the immune system, with marked expansion of CD38(+)CD8(+) T cells. Whether this expansion involves only viral-specific cells or includes a degree of bystander activation remains a matter of debate. We therefore examined the activation status of EBV-, CMV-, and influenza virus (FLU)-specific CD8(+) T cells during primary HIV infection, in comparison to HIV-specific CD8(+) T cells. The activation markers CD38 and HLA-DR were strongly expressed on HIV-specific CD8(+) T cells. Surprisingly, CD38 expression was also up-regulated on CD8(+) T cells specific for other viruses, albeit to a lesser extent. Activation marker expression returned to normal or near-normal values after 1 year of highly active antiretroviral therapy. HIV viral load correlated with CD38 expression on HIV-specific CD8(+) T cells but also on EBV-, CMV-, and FLU-specific CD8(+) T cells. In primary HIV infection, EBV-specific CD8(+) T cells also showed increased Ki67 expression and decreased Bcl-2 expression, compared with values observed in HIV-seronegative control subjects. These results show that bystander activation occurs during primary HIV infection, even though HIV-specific CD8(+) T cells express the highest level of activation. The role of this bystander activation in lymphocyte homeostasis and HIV pathogenesis remains to be determined.

Subpoblaciones de células T CD8+ en niños asintomáticos infectados verticalmente por el VIH-1

BACKGROUND AND OBJECTIVE

HIV-infection has distinct patterns of disease progression with heterogeneous manifestations. We analyzed the subsets of CD8+ T cells in a group of long term asymptomatic (LTA) HIV-1-infected children who had stable CD4+ T cell counts (> 600/l).

PATIENTS AND METHODS

Cross-sectional study in HIV-1-vertically infected children older than 7 years who were rated into two groups according to the clinical and immunological classification: a) LTA: 7 asymptomatic HIV-1-infected children in A1, and b) rapid progressor (PR): 14 age-matched C3 HIV-1-infected children. Controls included 17 age-matched uninfected children. Characterization of CD8+ T-cell subsets was done by three-color flow cytometry.

RESULTS

LTA children displayed similar values of memory CD8+ T cells (CD8+CD45RO+, CD8+CD45RA-CD28+, CD8+ CD45RA-CD62L+) as controls but lower than PR children. LTA patients also showed similar values of naïve CD8+ T cells (CD8+CD45RA+CD62L+, CD8+CD45RA+CD28+, CD8+CD45RA+, CD8+CD28+ and CD8+CD62L+) as controls but higher values than PR children. The values of CD8+CD38+ T cells were similar in LTA and controls but lower in PR. However, LTA children had higher values of CD8+HLA-DR+CD38+ and CD8+HLA-DR+ T cells than controls. Additionally, LTA patients had higher values of pre-effector CD8+ T cells than controls yet the values of effector CD8+ T-cells were similar in both LTA and controls. Moreover, the LTA group had lower values of CD8+CD11b+ T cells than controls.

CONCLUSIONS

Asymptomatic HIV-1 infected children have an almost normal CD8+ subset distribution, with the exception of activated and pre-effector CD8+ T cells which were higher.

Characterizing the immune system after long-term undetectable viral load in HIV-1-infected children

Thirty two HIV-infected children, on highly active antiretroviral therapy (HAART) and > 500 CD4+ T cells/mm3, were rated according to the time-course of viral load (VL) during the whole follow-up period (> 18 months) in a longitudinal retrospective study. (a) uVL group: 15 children with VL below 400 copies/mL; (b) dVL group: 17 children with higher VL. The uVL group showed higher memory (CD4+CD45RO+) T cells than did dVL group, and higher number of memory activated CD4+CD45RO+HLA-DR+ than did control group (healthy age-matched uninfected children), whereas CD4+CD45RA(hi)+CD62L+ was similar. However, TCR rearrangement excision circles (TRECs) were higher in uVL group than in dVL group. uVL Group showed CD8+CD45RO+ and CD8+CD45RO+CD38- higher number than the control group, but lower than the dVL group. The percentage of CD8+CD45RA(hi)+CD62L+, CD8+CD45RA+, CD8+CD62L-, and CD8+CD28+ was higher in uVL group than in dVL group, and lower than in control group. The uVL group showed higher number of activated (HLA-DR+CD38+, HLA-DR+, HLA-DR+CD38-) CD4+ T cells and lower percentages of CD4+HLA-DR-CD38+ than dVL group. In activated CD8- T cell, the uVL group had lower CD8+HLA-DR+CD38+, CD8+HLA-DR+, and CD8+CD38+ than the dVL group. Preeffector (CD8+CD57-CD28- and CD8+CD45RA-CD62L-) T cells were lower in the uVL group than in dVL group. In the effector (CD8+CD57+, CD8+CD57+CD28-, and CD8+CD45RA+CD62L-) T cells, HIV-infected-children had higher values than control group. HIV-infected-children who respond to HAART had TRECs reconstitution, decreased immune activation, and lower effector CD8+ T cells. Moreover, successful HAART allow the increment of activated CD4+ T cells.

T-lymphocyte populations in hepatitis C and HIV co-infected patients treated with interferon-alfa-2a and ribavirin

OBJECTIVE

The effects on T-lymphocyte populations of two interferon-alfa-2a (IFN) regimens associated with ribavirin were evaluated in 36 HCV-HIV co-infected patients with chronic hepatitis C, T-CD4 cell count > 250 cells/ micro L and a plasma viral load of < 10 000 HIV RNA copies/mL.

METHODS

Patients were given IFN for 48 weeks. Group A (18 patients) received 6 mega units (MU) subcutaneously three times a week for 24 weeks, then 3 MU three times a week for the last 24 weeks. Group B (18 patients) received 9 MU daily for 2 weeks, 3 MU daily for 22 weeks, then 3 MU three times a week for the last 24 weeks. Serum HCV RNA was evaluated at weeks 12 and 72. Ribavirin was added at week 16 for virologic nonresponders at week 12. CD3, CD3 CD4, CD3 CD8, CD3 CD4 human leucocyte antigen (HLA)-DR and CD3 CD8 HLA-DR lymphocyte subsets were evaluated before, during and after treatment by cytofluorometry. Controls were healthy and HCV mono-infected patients.

RESULTS

CD3 CD4 and CD3 CD8 T-cells counts were both impaired during anti-HCV therapy, but returned to baseline value after treatment completion. Lymphopenia concerned mainly CD8 T-cells, the percentage of which decreased, whereas that of CD4 increased. Three patients displayed reversible CD4 lymphopenia < 200 cells/ micro L. HIV infection at inclusion was responsible for higher CD3 CD8 HLA-DR T-cell percentages in co-infected patients than in healthy and HCV mono-infected subjects. T-cell sequestration in lymphoid tissues and enhanced apoptosis may account for lymphopenia.

CONCLUSION

High-dosed IFN anti-HCV therapy induced only moderate and transient CD4 lymphopenia in HIV co-infected patients.

Characterizing immune reconstitution after long-term highly active antiretroviral therapy in pediatric AIDS

In this study, we sought to characterize the T lymphocyte recovery in vertically HIV-1-infected children who respond to long-term highly active antiretroviral therapy (HAART). A 3-year longitudinal retrospective study was used to perform a cross-sectional study of 32 children rated according to the time course of CD4(+) T cell percentages in response to antiretroviral therapy and CDC clinical classification: (1) long-term asymptomatic (LTA group): 8 children in A1 during the whole follow-up period; (2) responsive to HAART (Rec group): 13 children in C3 before HAART who achieved CD4(+) T cell counts of > 500 cells/mm(3) after 3 years of HAART; and (3) nonresponsive to HAART (Non-Rec group): 11 children in C3 during the whole follow-up period despite 3 years of HAART. We also studied 17 healthy age-matched uninfected children as controls. Lymphoproliferative responses (LPRs) were evaluated by incorporation of [(3)H]thymidine, identification of T cell subsets by three-color flow cytometry, and determination of thymic production of T cells by quantification of T cell receptor rearrangement excision circles (TRECs). Interestingly, the Rec group showed an increase in percentage of CD4(+) T cells and a decrease in viral load, and recovered LPRs to mitogens and recall antigens, with values similar to those of the LTA group. Moreover, the Rec group produced similar percentages and absolute counts of naive (CD45RA(+)CD62L(+)) CD4(+) and CD8(+) T cells, and TRECs similar to those of the LTA group. In particular, the Rec group produced similar percentages of CD8(+)CD28(-)CD57(+) and CD8(+)CD28(-)CD57(-) T cell subsets compared with controls. Our data indicate that among children who have already progressed to AIDS and severe immunodeficiency but who respond to HAART, the immune system can recover and resemble those of nonprogressors or even uninfected children, in quantitative as well as in functional terms.

HIV-1 replication cycle

The HIV-1 is a formidable pathogen with establishment of a persistent infection based on the ability to integrate the proviral genome into chronically infected cells, and by the rapid evolution made possible by a high mutation rate and frequent recombination during the viral replication. HIV-1 has a variety of novel genes that facilitate viral persistence and regulation of HIV replication, but this virus also usurps cellular machinery for HIV replication, particularly during gene expression and virion assembly and budding. Recent success with antiretroviral therapy may be limited by the emergence HIV drug resistance and by toxicities and other requirements for successful long-term therapy. Further investigation of HIV-1 replication may allow identification of novel targets of antiretroviral therapy that may allow continued virus suppression in patients of failing current regiments, particularly drugs that target HIV-1 entry and HIV-1 integration.

[Different immune profiles according to the immunological and clinical progression in vertically HIV-infected children]

BACKGROUND

Our goal was to evaluate immunologic profile differences of HIV-infected children on antiretroviral treatment (ART). PATIENTS AND METHODDS: We studied 23 HIV-vertically infected children: a) N-A1 group: 10 HIV-infected children in A1 category; b) N-B2 group: 6 HIV-infected children in B2 category, and c) N-C3 group: 7 HIV-infected children in C3 category. We also studied 13 healthy age-matched HIV-negative children as controls. Cell proliferation was evaluated by incorporation of [3H]-Thymidine. The cytokine production in culture was quantified using commercially available specific ELISA assays. T-cell subsets were determined by flow cytometry.

RESULTS

Stimulation indexes of PHA, PWM, and anti-CD3+ anti-CD28 in N-A1 group were higher than in N-C3 group. In unstimulated PBMC, TNF-alpha production of HIV-infected children was higher than the control group (p < 0.05). However, in stimulated PBMC, TNF-alpha production in N-B2 and N-C3 groups was lower than the control group (p < 0.05). In HIV-infected children, CD8+ CD45RA+ CD62L+ T-cells were significantly lower (p < 0.01) and CD8+ CD45RO+ T-cells were higher (p < 0.05) than the control group. Moreover, in NA-1 group, CD4+ CD45RA+ CD62L+ T-cells were higher, and CD4+ CD45RO+ and CD8+ CD45RO+ T-cells were lower, than in N-B2 and N-C3 groups (p < 0.05). On the other hand, CD45RO+, CD45RO+ CD38+, HLA-DR+, CD38+ HLA-DR+ and CD38+ CD4+ and CD8+ T-cells were higher in N-C3 group than the N-A1 and control groups, except for CD4+ CD38+ T-cells. Activated CD8+ T-cells in N-A1 group were higher than in control group (p < 0.01).

CONCLUSION

Our data demonstrate that in spite of ART, there still remain important differences in the immunologic status of HIV-infected children depending on the HIV-infection stage.

Decrease in immune activation in HIV-infected patients treated with highly active antiretroviral therapy correlates with the function of hematopoietic progenitor cells and the number of naive CD4+ cells

This study was conducted to determine the impact of immune activation, cytokine production and apoptosis on the naive CD4+ cell count and the function of hematopoietic progenitor cells during the initial phase of highly active antiretroviral therapy (HAART). Blood samples from 11 HIV-infected patients were collected prior to HAART and after 4 and 12 weeks of therapy. Flow cytometry was used to determine the naive CD4+ count and activated T cells. The cloning efficiency of progenitor cells was determined using a colony-forming cells assay. Finally, apoptosis and cytokine production were determined. During the study period, the naive CD4+ count and the cloning efficiency increased significantly. Immune activation was found in HIV-infected patients and decreased during HAART. The level of immune activation correlated negatively with both the naive CD4+ count and the function of progenitor cells. A negative correlation was found between apoptosis and the naive CD4+ count. Alterations in cytokine production during HAART or correlation between cytokine production and the naive CD4+ count or the cloning efficiency of progenitor cells were not detected. In conclusion, immune activation in HIV-infected patients treated with HAART is inversely correlated with the function of progenitor cells and the naive CD4+ count.

Immunology and the REACH study: HIV immunology and preliminary findings. Reaching for Excellence in Adolescent Care and Health

This review paper presents the immunology findings in human immunodeficiency virus (HIV) infected and uninfected youth in the Reaching for Excellence in Adolescent Care and Health (REACH) Project within the context of basic and HIV immunology concepts. Methods employed in the study for specimen collection, management, and laboratory analysis are presented. This paper reviews published analyses of cross-sectional data; longitudinal analyses are underway. These preliminary data extend the work of others in demonstrating the potential for substantial thymic reserve in youth. This finding in HIV infected adolescents has implications for a fuller response to antiretroviral or immune-based therapies compared to that seen in adults. Dysregulation in mucosal immunity may appear before systemic HIV effects are seen and requires attention particularly to screening and treatment of genital co-infections. REACH has demonstrated gender differences in immunologic measures irrespective of HIV infection status.

Comparison of CD8(+) T-cell subsets in HIV-infected rapid progressor children versus non--rapid progressor children

BACKGROUND

CD8(+) T-cell subsets have not been adequately described in HIV-infected (HIV(+)) children classified with respect to disease progression as rapid-progressors (RPs) and non-rapid progressors (non-RPs).

OBJECTIVE

The purpose of this investigation was to determine the distribution of CD8(+) T-cell subsets in HIV(+) children and correlate the findings with degree of immunosuppression and HIV viral burden.

METHODS

By means of 3-color flow cytometry, percentages of CD38(+)DR(+), CD28(+), and CD57(+) CD8(+) T-cell subsets were examined in RP (n = 15) and non-RP (n = 36) HIV(+) children and in HIV-exposed but uninfected (n = 11) and HIVunexposed (n = 8) children. The CD8(+) T-cell subsets were correlated with mean CD4(+) T-cell percentages and HIV RNA levels. Analysis of covariance was used for group comparisons for the control of the covariate of age.

RESULTS

The HIV-exposed and HIV-unexposed controls were not different from each other in CD8(+) T-cell subset percentages, except that the DR(-)CD38(+)CD8(+) T-cell percentages were higher in the exposed controls than in the unexposed controls. RPs had a higher mean percentage of DR(+)CD38(+)CD8(+) T cells than non-RPs and both control groups, and RPs had higher viremia than non-RPs. CD38(+)CD8(+) T-cell percentages did not correlate with viral burden as it has been seen to do in HIV(+) adults. Percentages of CD28(+)CD8(+) T cells were lower in HIV-infected children than in controls. There was a positive correlation of percentage of CD28(+)CD57(-)CD8(+) T cells with CD4(+) T-cell percentages in each HIV-infected group.

CONCLUSION

CD8(+) T cells become activated (dual expression of DR and CD38) and lose CD28, some acquiring CD57, in relation to rapidity of disease progression in pediatric HIV infection.

[Relationship between T-cells subsets and prognostic markers in HIV-1-infected children]

BACKGROUND

To investigate the relationship between peripheral blood T-cell subsets and both CD4+ T-cell percentage and viral load (VL) in HIV-1-infected children.

PATIENTS AND METHOD

We studied 50 HIV-1-infected children on antiretroviral therapy. T-cell subsets were determined by flow cytometry. The VL was quantified using standardized molecular methods.

RESULTS

Memory (CD45RO+), activated memory (CD45RO+HLA-DR+) and CD45RA-CD62L+ (memory cells expressing L-selectin) CD4+ and CD8+ T-cells correlated positively with the VL and negatively with the percentage of CD4+ T-cells. Inversely, naive CD4+ and CD8+ T-cells (CD45RA+CD62L+) correlated positively with the percentage of CD4+ T-cells and negatively with the VL. HLA-DR+, CD38+ or HLA-DR+CD38+CD4+ and CD8+ T-cells correlated also positively with the VL and negatively with the percentage of CD4+ T-cells (with the exception of CD4+CD38+ which did not show any association with the VL). CD8+CD28+ T-cells correlated positively with the percentage of CD4+ T-cells and negatively with the VL, whereas CD8+ CD57+ and CD8+CD28-CD57+ exhibited an opposite association.

CONCLUSIONS

Our data suggest a relationship between the different lymphocyte subsets (memory, naïve, activated and effector T-cells) and the most commonly used markers in clinical practice, namely the viral load and the CD4+ T-cell percentage. Some of these subsets may be useful to determine the virologic and immunologic status in HIV-1-infected children.

Association of CD8+ T lymphocyte subsets with the most commonly used markers to monitor HIV type 1 infection in children treated with highly active antiretroviral therapy

In contrast to adults, there is no information about children concerning the effects of the new antiretroviral therapy on the chronic activation and expansion of CD8+ T cells. We have investigated the relationship between blood CD8(+) T cell subsets, with percent CD4+ cells (%CD4), percent CD8+ cells (%CD8), and plasma viral load (VL), in 39 vertically HIV-1-infected children receiving highly active antiretroviral therapy (HAART) (mean age, 7.6 years; range, 2-15.6 years). CD8+ subsets were examined by three-color multiparametric flow cytometry, and VL was quantified by standard assays. There was a strong positive correlation between activated CD8+ T cells and VL. An increase in memory and memory-activated CD8+ T cells correlated with increased VL, whereas nonactivated memory cells and CD28+ CD8+ T cells correlated negatively with VL. Naive and effector cells did not correlate with VL, although the CD8+ CD45RA -CD62L- subset correlated with increased VL. Activated CD8(+) T cells did not correlate with %CD4, but an increase in memory-activated and effector CD8+ T cells was associated with lower %CD4. Increased naive CD8+ and CD28 +CD8+ T cells showed a positive correlation with %CD4 and a negative correlation with %CD8. In conclusion, in HIV-1-infected children receiving HAART, the activation of CD8+ T cells is associated with high VL, whereas CD8 +CD28+ and nonactivated CD8+ memory cells are associated with lower viral load. Naive CD8+ and CD28 +CD8+ T cells are associated with an improved immunological status.

Protease-sparing regimen in a real-life practice with naïve patients: an equal opportunity approach?

PURPOSE

Proven clinical efficacy of protease-sparing regimens (PSR) has been shown. Concerns exist about broad applicability of these regimens in advanced naïve patients. Recent reports have associated a rise in liver enzymes with nevi rapine; however, no data exist with efavirenz.

METHOD

17 consecutive antiretroviral-naïve HIV patients were started on a PSR with efavirenz plus two nucleoside reverse transcriptase inhibitors. Baseline liver enzymes, serum CD38, CD4, and HIV viral load data were collected. Correlation between change in viral load and immune reconstitution on therapy were compared to baseline laboratory values.

RESULTS

All patients had a mean viral load decrease of >2 logs, including patients with low initial CD4% or high viral load, and there was no increase of liver enzymes observed at a median follow-up of 42 weeks (range 17-78). There was a perfect correlation between the change in viral load and the initial viral load (p <.0001, r = 1.00) including patients with viral load > or =100,000 copies/mL and CD4 count< or =50 (n = 5). Even patients with low initial CD4 had a significant percentage increase in CD4 count (p <.0002, r = 0.7880). CD38% showed a positive correlation with change in viral load (p =.046, r = 0.522).

CONCLUSION

All patients experienced a mean viral load decrease of >2 logs (88% less than 400 copies/mL and 35% less than 20 copies/mL). There were no observed increases in liver enzymes. Patients with low CD4 counts, high initial viral load, or high CD38 expression still experienced a significant change in viral load.

Comparison of T-cell subsets' reconstitution after 12 months of highly active antiretroviral therapy initiated during early versus advanced states of HIV disease

This research comprised a pilot open prospective clinical study comparing T-cell subset reconstitution in antiretroviral-naive patients, after 12 months of HAART when treatment was initiated in early stages (ES; n = 18) of infection versus advanced stages (AS; n = 20).

CONTROL GROUP

10 healthy HIV-negative individuals. Immunophenotypic markers were evaluated before and after 6-and 12-months' therapy. Functional assays were performed in one subset.

RESULTS

Viral load (VL) was < 200 copies/ml in all patients. Median percentages of CD4+ pretherapy were 33% and 6%, respectively, in the ES and AS groups, increment after 12 months of therapy was +15% and +13% respectively. Only the ES group achieved normal values. Declines of CD8+ percentage were significantly higher in the ES (-18%) than in the AS group (-2%). CD4+ memory and naive cells in the ES group were similar to those of controls before treatment and did not change after therapy. In contrast, CD4+ memory and naive cells in the AS group did not reach normal levels despite treatment. In the ES group, there was a significant increment in CD8+ naive cells (+8%) and a decrement in CD8+CD38+ cells (-17%), both populations reached values close to normal, whereas these subsets remained far from normal in the AS group. Improvement of lymphoproliferative response after therapy was observed in both groups. One patient in the ES group showed positive LPR against p24 after treatment. After 12 months' highly active antiretroviral therapy, only those who began such therapy in ES disease reached values within the range of healthy controls. To achieve a more complete immunologic reconstitution, early initiation of potent antiretroviral therapy should be recommended.

A single measurement of CD38CD8 cells in HIV+, long-term surviving injecting drug users distinguishes those who will progress to AIDS from those who will remain stable

This study compares the predictive power of a single measurement of CD8+CD38+, CD8+CD45RO+ or CD8+CD38+CD45RO+ subpopulations in predicting progression to AIDS in a cohort of HIV+ long-term surviving injecting drug users. The results showed that both the total CD8+ percentage, and the CD8+CD38+ and CD8+CD38+CD45RO+ subpopulations of cells all individually predicted progression to AIDS. In combination with CD4, only the CD8+CD38+ subpopulation enhanced the predictive power of the CD4 percentage alone. The CD8+ percentage correlated negatively with the CD4 percentage and the CD8+CD45RO+ subpopulation did not predict disease progression. The proportion of CD8+CD38+ cells identified which patients with a moderate CD4 level were more likely to progress to AIDS, and conversely, which patients with a low CD4 count were likely to remain clinically stable. The results were consistent irrespective of whether time was measured from the date of seroconversion, or from the date of the test. This study is the first to measure these markers in HIV-infected injecting drug users, and in long-term survivors. The results demonstrate the considerable added value of the CD8+CD38+ cell percentage over the CD4 count alone, in predicting HIV clinical progression.

Immunological benefits of antiretroviral therapy in very early stages of asymptomatic chronic HIV-1 infection

OBJECTIVES

To assess whether an almost complete restoration of immune system can be achieved when antiretroviral therapy is initiated at very early stages of asymptomatic chronic HIV-1 infection.

DESIGN

T cell subsets and cell-mediated responses were analysed at baseline and after 12 months of either a double or a triple antiretroviral therapy in 26 asymptomatic HIV-1-infected patients with CD4 T cell counts > 500 x 10(6) cells/l and a baseline plasma viral load > 10000 copies/ml.

RESULTS

Triple therapy was significantly more effective in reducing plasma HIV RNA to undetectable levels, in returning CD4:CD8 ratio to nearly normal levels, in reducing activated cells (CD38) and in increasing naive (CD45RA+CD45RO-) and memory (CD45RA-CD45RO+) CD4 cells. Both double and triple therapies caused a clear decrease in memory (CD45RA-CD45RO+) CD8 cells as well as a significant increase in the CD28 subset of CD8 cells. At baseline, there was an important increase in cells producing interferon-gamma (IFNgamma) with no significant abnormalities in T lymphocytes producing interleukin 2 (IL-2), tumour necrosis factor alpha and interleukin 4. Both types of therapy reduced IFNgamma- and IL2-producing CD4 T lymphocytes while IFNgamma-producing CD8 cells remained increased. Even before therapy, these HIV-1-positive patients lacked significant abnormalities in the T cell responsiveness to polyclonal stimuli as well as in the secretion of CCR5 chemokines by peripheral blood mononuclear cells.

CONCLUSIONS

Initiating highly active antiretroviral therapy at very early stages of chronic HIV-1 infection allows rapid and almost complete normalization of T cell subsets and preservation of T cell functions. These early-treated patients could be excellent candidates for receiving additional HIV-specific immune-based therapies, which might be essential for the control of HIV infection.

Activation of CD8 T cells normalizes and correlates with the level of infectious provirus in tonsils during highly active antiretroviral therapy in early HIV-1 infection

OBJECTIVES

To study the effects of antiretroviral therapy on T cell activation in blood and tonsils from HIV-1 infected individuals in relation to CD4 cell count, plasma viremia, and infectious HIV-1 provirus.

DESIGN

A 48-week study of viral load and T cell subsets in blood and tonsils from 12 HIV-1-positive individuals with a mean CD4 cell number of 400 x 10(6) cells/l treated with a combination of zidovudine, lamivudine, and indinavir.

METHODS

Tonsil biopsies and blood samples were collected at regular intervals. Lymphocytes were phenotyped and quantified by three-color flow cytometry; infectious provirus was quantified by a limiting dilution assay. HIV-1-negative individuals were included as controls.

RESULTS

The fraction of tonsillar CD8 T cells expressing CD69, CD38, or HLA-DR in the patients with suppressed virus replication declined to levels comparable with that in controls by 48 weeks and showed a strong positive correlation with tonsillar infectious provirus and plasma viremia. The level of CD4 T cell activation was within normal range in tonsils throughout the study. The fraction of HLA-DR+ cells within CD4 and CD8 T cells in blood declined rapidly in parallel with plasma viremia but remained slightly higher compared with that in uninfected individuals.

CONCLUSION

Antiretroviral therapy normalizes tonsillar CD8 T cell activation in HIV-1-positive individuals in parallel with suppression of viral replication, indicating reduced CD8 cell turnover. Normal tonsillar CD4 T cell activation suggests limited CD4 cell turnover in early HIV infection. Activated CD8 T cells in lymphoid tissue is superior to that in blood as an immunological marker for the virological response to antiretroviral therapy.

Effect of long-term infection with nef-defective attenuated HIV type 1 on CD4+ and CD8+ T lymphocytes: increased CD45RO+CD4+ T lymphocytes and limited activation of CD8+ T lymphocytes

Members of the Sydney Blood Bank Cohort (SBBC) have been infected with an attenuated strain of HIV-1 with a natural nef/LTR mutation and have maintained relatively stable CD4+ T lymphocyte counts for 14-18 years. Flow cytometric analysis was used to examine the phenotype of CD4+ and CD8+ T lymphocytes in these subjects, including the immunologically important naive (CD45RA+CD62L+), primed (CD45RO+), and activated (CD38+HLA-DR+ and CD28-) subsets. The median values were compared between the SBBC and control groups, comprising age-, sex-, and transfusion-matched HIV-1-uninfected subjects; transfusion-acquired HIV-1-positive LTNPs; and sexually acquired HIV-1-positive LTNPs. Members of the SBBC not only had normal levels of naive CD4+ and CD8+ T lymphocytes, but had primed CD45RO+ CD4+ T lymphocytes at or above normal levels. Furthermore, these primed cells expressed markers suggesting recent exposure to specific antigen. SBBC members exhibited variable activation of CD8+ T lymphocytes. In particular, SBBC members with undetectable plasma HIV-1 RNA had normal levels of activated CD8+ T lymphocytes. Therefore, the result of long-term infection with natural nef/LTR mutant HIV-1 in these subjects suggests a decreased cytopathic effect of attenuated HIV-1 on susceptible activated CD4+ T lymphocyte subsets in vivo, and minimal activation of CD8+ T lymphocytes.

Prospective study of CD8+ lymphocyte activation in relation to viral load in HIV-infected patients with > or = 400 CD4+ lymphocytes per microliter

To investigate the temporal relationship between CD8+ lymphocyte phenotypic alterations, the CD4+ T cell decline, and plasma HIV RNA levels during the natural history of HIV infection, 33 treatment-naive HIV-infected patients with > or =400 CD4+ cells/microl were studied prospectively for 3 years. During the study period, 20 patients remained untreated, and only 6 received more than 6 months of therapy. A significant relationship was found between changes in plasma HIV RNA and changes in the proportion of CD38+CD8+ cells. Conversely, the number of CD4+ T cells lost per year was strongly related to the increase in the proportion of CD28-CD8+ T cells. A strong relationship between mean yearly changes in CD4+ T cell numbers and changes in HIV RNA was also observed. CD4+ T cell changes were associated with changes in both viral load and CD8+ T cell activation. These results provide support for the use of both virologic and immunologic parameters for prognosis and management during HIV infection.

Immune reconstitution in HIV-1 infected subjects treated with potent antiretroviral therapy

The introduction of potent antiretroviral drug regimens contributed to a decline in HIV-1 associated morbidity and mortality. Clinical observations of spontaneous remission of previously untreatable opportunistic infections in subjects on highly active antiretroviral therapy (HAART) reflect the substantial degree of immune reconstitution which can be achieved by those therapies. A biphasic increase of CD4+ T lymphocytes has been reported including naive (CD45RA+) and memory (CD45RO+) cell subsets. Proliferative lymphocyte responses to recall antigens and mitogens are enhanced over time, while T lymphocyte activation is largely reduced and T cell receptor (TCR) repertoires are partly restored. Proliferative lymphocyte responses specific to HIV-1 antigens, in contrast, remain weak. A complete normalisation of HIV-1 associated immunological alterations has not been reported so far, but the observation period of subjects on potent antiretroviral therapies is still relatively short.

Perforin is not co-expressed with granzyme A within cytotoxic granules in CD8 T lymphocytes present in lymphoid tissue during chronic HIV infection

BACKGROUND

Residual HIV-1-infected cells are poorly eliminated from lymphoid tissue (LT) reservoirs by effector cytotoxic T lymphocytes (eCTL) despite antiretroviral therapy. Perforin and granzyme A (grA) constitute major effector molecules within eCTL granules that induce apoptosis and lysis of virally infected cells.

OBJECTIVE

Expression of perforin and grA was studied at the single cell level in LT and blood from 16 patients infected with HIV-1 (stage A1-C) who were not taking antiretroviral therapy.

METHOD

Immunohistochemical analysis by in situ imaging of cells from blood and LT.

RESULTS

Quantitative in situ imaging showed that perforin-expressing CD8 T cells comprised 0.3-1.5% of total cells within the LT from recent HIV-1 seroconverters, while grA was found in 2.1-7.2% of total cells. However, despite high-level grA upregulation (1.5-4.5% of total cells) compared with that in non-infected individuals (0.4-0.9%), perforin expression remained low (< 0.1% of total cells) (P < 0.02) in LT from patients with chronic HIV-1 infection (stage A2-C). This contrasted with findings in peripheral blood mononuclear cells (PBMC) from the same HIV-1 infected cohort where perforin was detected in 13-31% of all PBMC, which was 10- to 100-fold higher than in lymphoid tissue (P < 0.001); grA was found in 14-32% of total PBMC. Two-colour staining showed that granular expression of perforin and grA was restricted to CD8 T cells in over 90% of total cells in both LT and blood.

CONCLUSIONS

These findings indicate that cytotoxic perforin expression is impaired at local sites of HIV replication within lymphoid tissue. Since perforin is required together with grA for granule-mediated cytolysis, the low perforin expression in the LT may limit the ability of eCTL to eliminate HIV-1 infected cells in lymphoid tissue.

Phenotypic analysis of CD8+ T lymphocytes in a cohort of HIV type 1-infected patients treated with saquinavir, ritonavir, and two nucleoside analogs for 1 year, and association with plasma HIV type 1 RNA

The phenotype of circulating CD8+ T lymphocytes and its association with plasma HIV-1 RNA were analyzed in 34 HIV-1-infected subjects, who were treated with saquinavir, ritonavir, and two nucleoside analogs (HAART) for 1 year. Four-color flow cytometry was applied to measure the expression of cell surface antigens CD38, HLA-DR, CD45RA, CD28, and CD62L on CD8+ T lymphocytes. The results were compared with data on 35 HIV-1-seronegative subjects, 18 untreated asymptomatic HIV-1-seropositive individuals, and 24 HIV-1-infected subjects receiving reverse transcriptase inhibitors (RTIs). Subjects receiving HAART showed a significantly elevated number and percentage of CD38- and HLA-DR-positive and CD28-negative CD8+ T lymphocytes as well as a lower percentage of naive (CD45RA+62L+) CD8+ T lymphocytes compared with HIV-1-uninfected controls. Even subjects with undetectable plasma HIV-1 RNA showed a persistent elevation of activated CD8+ T lymphocytes. However, fewer activated CD8+ T lymphocytes were observed in subjects receiving HAART than in untreated individuals and subjects administered RTIs. In individuals receiving RTIs, CD8+ cell activation was not significantly reduced compared with untreated subjects. Of all evaluated activation markers, the percentage of CD8+ T lymphocytes expressing CD38 and the combination of CD38 and HLA-DR showed the best correlation with plasma HIV-1 RNA. The persistence of CD8+ T lymphocyte activation in subjects receiving HAART strongly suggests ongoing viral activity, even in subjects with undetectable plasma HIV-1 RNA. A complete normalization of immunologic changes of CD8+ T lymphocytes would therefore require a more potent drug regimen or a longer duration of therapy.

C1.7 Antigen Expression on CD8+ T Cells Is Activation Dependent: Increased Proportion of C1.7+CD8+ T Cells in HIV-1-Infected Patients with Progressing Disease

The C1.7 Ag is a surface marker previously shown to be expressed on all NK cells and on a subset of CD8+ T cells. We report in this study that C1.7 Ag expression on peripheral blood-derived CD8+ T cells overlaps with activation markers S6F1high and CD29high and is reciprocally expressed with CD62L. C1.7 Ag expression can be induced in vitro on CD8+ T cells by anti-CD3 cross-linking, suggesting that C1.7 Ag is activation dependent. In contrast to NK cells, C1.7 Ag does not signal on CD8+ T cells, nor does it induce redirected lysis upon ligation. The proportion of C1.7 Ag+CD8+ T cells is increased in HIV-infected patients compared with healthy donors. In 69 HIV-infected patients, we observed a significant inverse correlation between the percentage of C1.7 Ag-expressing CD8+ T cells and the absolute CD4+ T cell count. Two-year clinical follow-up of patients with initial CD4+ T cell count of &gt;400 cells/mm3 and a normal proportion of C1.7 Ag+CD8+ T cells revealed that these patients were clinically stable with minimal HIV-associated symptoms. In contrast, 10 of 12 patients with CD4+ T cell counts of &gt;400 cells/mm3 and an elevated proportion of C1.7 Ag+CD8+ T cells were symptomatic. ANOVA analysis of patients indicates that C1.7 Ag is a better predictor of disease progression than CD4 count. Overall, our findings indicate that C1.7 Ag is the first described marker for activated/memory CD8+ T cells and a useful parameter for evaluating the level of CD8+ T cell activation in vivo.

Expansion of CD57 and CD62L-CD45RA+ CD8 T lymphocytes correlates with reduced viral plasma RNA after primary HIV infection

OBJECTIVE

CD8 T cells, expressing cell surface molecules distinct from those on resting and naive T cells, are increased in HIV infection. The association of increased CD38 and human leukocyte antigen DR (HLA-DR) CD8 T cells with poor prognosis has suggested that activated CD8 T cells may aggravate HIV infection. We examined whether other immunological parameters might influence the viral setpoint.

DESIGN

Peripheral T cells from nine untreated patients, obtained after primary HIV infection when plasma HIV had stabilized, were examined for proteins expressed in activated versus resting, memory versus naive, and cytolytic versus non-cytolytic T cells.

METHODS

The proportion of CD8 T cells that stain for CD38 and HLA-DR, CD28 and CD57 was compared with plasma viraemia and CD4 cell count. These parameters were also compared with the proportion of CD4 and CD8 T cells that express CD62L and CD45RA, present on naive cells and down-modulated in memory cells. Internal staining for the cytotoxic protein granzyme A was also examined.

RESULTS

An increase in CD38 and CD38 HLA-DR CD8 T cells correlated with increased plasma viral RNA (P < 0.00002, P < 0.03, respectively). An increase in CD8 T cells expressing granzyme A was associated with lower CD4 cell counts (P < 0.04). However, the expansion of CD57 and CD62L CD45RA+ CD8 T cells was associated with a lower viral setpoint (P < 0.01, P < 0.02, respectively).

CONCLUSION

Phenotypically defined activated CD8 T cells may have different functions in HIV infection. Activated CD8 T cells that are CD57 or CD62L(-)CD45RA+ may be beneficial, because their expansion in untreated patients correlates with a reduced viral setpoint after primary infection.

CD8+ lymphocytes in pregnancy and HIV infection: characterization of CD8+ subpopulations and CD8+ noncytotoxic antiviral activity

The distribution and function of lymphocytes vary in different clinical states. The object of this study was to characterize the CD8+ lymphocyte subpopulations and CD8+ anti-HIV suppressor activity in HIV-infected and uninfected pregnant and nonpregnant women. The total percentage of CD8+ lymphocytes was not altered by pregnancy but the percentage of activated CD8+ T cells increased during pregnancy and decreased postpartum. HIV infection in pregnant women resulted in both an increased percentage of CD8+ lymphocytes and a marked increase in activated and memory CD8+ lymphocyte subsets, which did not change in the postpartum period. Most HIV-infected women had CD8+-mediated noncytotoxic antiviral activity. However, the activity was not correlated with alterations in CD8+ lymphocyte subsets. This study provides baseline information on changes in CD8 immunologic parameters during pregnancy and HIV infection for further studies that employ antiretroviral therapeutic regimens capable of impacting the immune response.

Expression of CD28 and CD38 by CD8+ T lymphocytes in HIV-1 infection correlates with markers of disease severity and changes towards normalization under treatment. The Swiss HIV Cohort Study

The relationship between blood CD8+ T lymphocyte subsets, as defined by CD28 and CD38 expression, and plasma viraemia and CD4+ T cells in HIV-1 infection was investigated. In a cross-sectional study of 46 patients with either no or stable anti-retroviral treatment, there was a strong negative correlation between the percentage of CD8+CD28- and the percentage of CD4+ T cells (r = -0.75, P < 0.0001), and a positive correlation between absolute numbers of CD8+CD28+ and CD4+ T cells (r = 0.56, P < 0.0001). In contrast, the expression of CD38 by CD8+ T lymphocytes correlated primarily with plasma viraemia (e.g. the percentage of CD38+ in CD8bright cells, r = 0.76, P < 0.0001). In the 6 months following triple therapy initiation in 32 subjects, there was a close correlation between changes (delta) in CD8+CD28+ or CD8+CD28- and in CD4+ T cells (e.g. delta % CD8+CD28+ versus delta % CD4+, r = 0.37, P = 0.0002; delta % CD8+CD28- versus delta % CD4+, r = -0.66, P < 0.0001). A marked decline of the number of CD8+ T cells expressing CD38 was also observed. These results suggest the existence of a T cell homeostasis mechanism operating in blood with CD4+ and CD8+CD28+ cells on the one hand, and with CD8+CD28- cells on the other. In addition, the percentage of CD38+ cells in CD8+ cells, generally considered an independent prognostic factor, could merely reflect plasma viral load.

Highly active antiretroviral therapy during early HIV infection reverses T-cell activation and maturation abnormalities. Swiss HIV Cohort Study

OBJECTIVES

To evaluate the impact of early initiation of highly active antiretroviral therapy (HAART) on disease-induced T-cell activation and maturation abnormalities during asymptomatic HIV infection.

DESIGN

A prospective open-label trial of zidovudine, lamivudine and ritonavir in treatment-naive asymptomatic HIV-infected individuals with CD4 cells > or = 400 x 10(6)/l.

METHODS

Peripheral blood CD4+ and CD8+ T cells derived from 15 asymptomatic HIV-infected individuals (median baseline CD4+ cells, 608 x 10(6)/l; CD8+ cells, 894 x 10(6)/l; plasma HIV RNA, 3.93 log10 copies/ml) undergoing therapy with zidovudine (300 mg twice daily), lamivudine (150 mg twice daily), and ritonavir (600 mg twice daily) were assessed for changes in expression of phenotypic markers of T-cell activation (HLA-DR and CD38) and maturation (CD45RA and CD45RO). At weeks 0, 2, 4, 8, 12, 16, 20 and 24, T-cell subsets were quantified by flow cytometry and plasma HIV viral loads determined using reverse transcription PCR.

RESULTS

HAART-induced decrease in plasma HIV RNA levels coincided with a significant reduction in numbers of activated CD4+/HLA-DR+ (maximum change, -36%; P < or = 0.05), CD8+/HLA-DR+ (maximum change, -66%; P < or = 0.005) and CD8+/CD38+ (maximum change, -51%; P < or = 0.01) T cells. A concomitant significant increase in numbers of naive CD4+/CD45RA+ (maximum change, +12%; P < or = 0.005) and memory CD4+/CD45RO+ (maximum change, +6%; P < or = 0.05) T cells was also evident, which contrasted with a significant decrease in memory CD8+/CD45RO+ cells (maximum change, -42%; P < or = 0.005).

CONCLUSION

The observed ability of HAART during early asymptomatic HIV infection to initiate rapid reversal of disease-induced T-cell activation and maturation abnormalities, while preserving pretherapy levels of immune function, supports the concept that therapeutic advantage is to be gained by commencing early aggressive antiretroviral therapy.

Highly active antiretroviral therapy results in a decrease in CD8+ T cell activation and preferential reconstitution of the peripheral CD4+ T cell population with memory rather than naive cells

OBJECTIVE

Highly active antiretroviral therapy (HAART) can produce marked increases in peripheral blood CD4+ T cells and decreases in HIV plasma RNA copy numbers. However, it is not clear whether these absolute changes will be accompanied by a recovery in the known naive CD4+ T cell depletion or a decrease in the marked CD8+ T cell activation.

DESIGN

Twenty-nine patients were enrolled in studies of either nucleoside therapy alone or nucleoside therapy combined with a protease inhibitor (zidovudine + lamivudine + indinavir). One hundred and ninety-one examinations were carried out at three baseline time points and during 40 weeks of follow-up to evaluate the effect of HAART on CD4+ memory/naive phenotype and CD8+ T cell activation.

METHODS

CD4+ and CD8+ T cell number, CD62L/CD45RA expression on CD4+ T cells and CD38 expression on CD8+ T cells were measured by three-color flow cytometry.

RESULTS

Most protease inhibitor treated patients had a significant rise in CD4+ numbers. The marked rise in the CD4+ T cells seen in individuals in this study was not accompanied over a 40-week period by a change in the abnormally low CD4+ naive compartment, and thus was almost completely of memory phenotype. The CD38 expression on CD8+ cells fell during treatment, and decreased to a greater degree than the comparable rise in CD4+ T cell counts. This decrease continued in many patients after the CD4+ T cell rise or viral load decline had plateaued.

CONCLUSION

HAART results in changes in activation to a greater extent than absolute changes in CD4+ T cell numbers, but is not accompanied by an increase in naive CD4+ T cells. Measurements of CD4+ T cell numbers alone may not allow appropriate interpretation of immune activation or immune competence in patients receiving those drugs.

Immunologic effects of combined protease inhibitor and reverse transcriptase inhibitor therapy in previously treated chronic HIV-1 infection

OBJECTIVE

To evaluate the efficacy of combination protease and reverse transcriptase inhibitor therapy in correcting HIV-1-induced lymphocyte subset abnormalities in previously treated adults.

DESIGN

A 48-week observational study of lymphocyte subsets in 12 participants in the Multicenter AIDS Cohort Study who were already taking at least one reverse transcriptase inhibitor and added a protease inhibitor to their treatment regimen. Comparison groups were HIV-seronegative homosexual men, HIV-seronegative heterosexual men, and homosexual HIV-1-infected men who were long-term non-progressors.

METHODS

Three-color immunofluorescence and monoclonal antibodies were used to assess HIV-1-induced lymphocyte subset alterations related to immune deficiency and immune activation. Plasma HIV-1 RNA levels were monitored to assess suppression of viral replication.

RESULTS

CD4+ cell counts significantly increased and lymphocyte activation measured as CD38 and HLA-DR expression on CD8+ T cells significantly decreased by 48 weeks. CD4+ cell values remained abnormal even in those who were fully suppressed. Some T-cell activation markers decreased to levels observed in long-term non-progressors. The increase in CD4+ T-cell numbers reached a plateau by week 24, but the increase in resting HLA-DR- CD38-T cells was sustained through week 48. Proportions of CD45RA+ CD62L-selectin+ and CD28+ CD4+ T-cell subsets and Fas expression were not abnormal at baseline compared with seronegative homosexual controls.

CONCLUSIONS

The most significant impact of suppression of viral replication was reversal of T-cell activation. However, normalization of lymphocyte subset perturbations associated with chronic HIV-1 infection was not achieved after 1 year of treatment with current combination antiretroviral regimens. More profound viral suppression, therapy for longer than 1 year, or immunologic augmentation may be needed to fully reverse the abnormalities.