Human immunodeficiency virus type 1 Rev- and Tat-specific cytotoxic T lymphocyte frequencies inversely correlate with rapid progression to AIDS

Immunological correlates of AIDS-free survival after human immunodeficiency virus type 1 (HIV-1) infection are largely unknown. Cytotoxic T lymphocyte (CTL) responses are generally believed to be a major component of protective immunity against viral infections. However, the relationship between HIV-1-specific CTL responses and disease progression rate is presently unclear. Here we show in twelve HIV-1-infected individuals that detection of Rev-specific CTL precursors (CTLp) early in the asymptomatic stage, as well as detection of Rev- and Tat-specific CTLp later during follow-up, inversely correlate with rapid disease progression. No such correlation was found for detection of CTLp against Gag, RT or Nef. Further studies are required to determine whether a protective mechanism is indeed the basis of the observed correlation. The data presented are in agreement with the hypothesis that CTL against proteins that are important for early viral transcription and translation are of particular importance in protection from rapid disease progression.

The role of CD4+ and CD8+ T cells in the destruction of islet grafts by spontaneously diabetic mice

Spontaneous development of diabetes in the nonobese diabetic (NOD) mouse is mediated by an immunological process. In disease-transfer experiments, the activation of diabetes has been reported to require participation of both CD4+ and CD8+ T-cell subsets. These findings seem to indicate that the CD4+ cells are the helper cells for the activation of cytotoxic CD8+ cells that directly destroy islet beta cells in type I diabetes. In this report we challenge this interpretation because of two observations: (i) Destruction of syngeneic islet grafts by spontaneously diabetic NOD mice (disease recurrence) is CD4+ and not CD8+ T-cell dependent. (ii) Disease recurrence in islet tissue grafted to diabetic NOD mice is not restricted by islet major histocompatibility complex antigens. From these observations we propose that islet destruction depends on CD4+ effector T cells that are restricted by major histocompatibility complex antigens expressed on NOD antigen-presenting cells. Both of these findings argue against the CD8+ T cell as a mediator of direct islet damage. We postulate that islet damage in the NOD mouse results from a CD4+ T-cell-dependent inflammatory response.

Functional T cell reconstitution and human immunodeficiency virus-1-specific cell-mediated immunity during highly active antiretroviral therapy

Lymphoproliferative responses (LPRs) to recall antigens (Ags) and human immunodeficiency virus type 1 (HIV-1) Gag and frequencies of circulating HIV-1-specific cytotoxic T lymphocyte precursors (CTLps) were measured in 12 patients undergoing highly active antiretroviral therapy (HAART) after long-standing HIV-1 infection. LPRs to at least 1 recall Ag became detectable or increased in all patients during HAART. No significant LPRs to Gag-p24 were observed, whereas 4 of 8 patients tested presented with Gag-p17-specific LPRs. HIV-1-specific CTLp frequencies became measurable or increased early during therapy in 6 of 10 patients tested and were maintained or decreased thereafter. Increasing HIV-1-specific CTLp frequencies were seen only in association with partial HAART failure in 1 patient. In conclusion, restoration of CD4+ T lymphocyte responsiveness to recall Ags is achieved during HAART. The data provide evidence for limited HIV-1-specific CD4+ memory T cells during advanced HIV-1 infection and suggest that both CD4+ and CD8+ HIV-1-specific T cells are poorly stimulated when viral load is suppressed.

Longitudinal analysis of human immunodeficiency virus type 1-specific cytotoxic T lymphocyte responses: a predominant gag-specific response is associated with nonprogressive infection

To establish correlates of protective immunity during human immunodeficiency virus type 1 (HIV-1) infection, the frequencies of circulating cytotoxic T lymphocyte (CTL) precursors (p) directed against 4 HIV-1 gene products (reverse transcriptase, gag, nef, and env) were evaluated in HIV-1-infected homosexual men who progressed to AIDS and in long-term survivors over time. For both groups, HIV-1-specific CTL responses had similar kinetics and magnitude. At maximum expansion, HIV-1-specific CTLp had a median frequency of 0.2% mononuclear cells in both progressors and long-term survivors, with peaks of 0.5% and 2%, respectively. Long-term survivors maintained the established CTLp pool and presented a persistently predominant gag-specific response. The fraction and, to a lesser extent, the frequency of gag-specific CTLp were inversely correlated with virus load. In progressors, general T cell function and measurable HIV-1-specific CTLp frequencies dropped simultaneously, suggesting a further loss of virus control due to the ensuing immunodeficiency.

High Treatment Uptake in Human Immunodeficiency Virus/Hepatitis C Virus-Coinfected Patients After Unrestricted Access to Direct-Acting Antivirals in the Netherlands

Background

The Netherlands has provided unrestricted access to direct-acting antivirals (DAAs) since November 2015. We analyzed the nationwide hepatitis C virus (HCV) treatment uptake among patients coinfected with human immunodeficiency virus (HIV) and HCV.

Methods

Data were obtained from the ATHENA HIV observational cohort in which >98% of HIV-infected patients ever registered since 1998 are included. Patients were included if they ever had 1 positive HCV RNA result, did not have spontaneous clearance, and were known to still be in care. Treatment uptake and outcome were assessed. When patients were treated more than once, data were included from only the most recent treatment episode. Data were updated until February 2017. In addition, each treatment center was queried in April 2017 for a data update on DAA treatment and achieved sustained virological response.

Results

Of 23574 HIV-infected patients ever linked to care, 1471 HCV-coinfected patients (69% men who have sex with men, 15% persons who [formerly] injected drugs, and 15% with another HIV transmission route) fulfilled the inclusion criteria. Of these, 87% (1284 of 1471) had ever initiated HCV treatment between 2000 and 2017, 76% (1124 of 1471) had their HCV infection cured; DAA treatment results were pending in 6% (92 of 1471). Among men who have sex with men, 83% (844 of 1022) had their HCV infection cured, and DAA treatment results were pending in 6% (66 of 1022). Overall, 187 patients had never initiated treatment, DAAs had failed in 14, and a pegylated interferon-alfa-based regimen had failed in 54.

Conclusions

Fifteen months after unrestricted DAA availability the majority of HIV/HCV-coinfected patients in the Netherlands have their HCV infection cured (76%) or are awaiting DAA treatment results (6%). This rapid treatment scale-up may contribute to future HCV elimination among these patients.

Lymphoproliferative response to HIV type 1 p24 in long-term survivors of HIV type 1 infection is predictive of persistent AIDS-free infection

To establish immunologic correlates of progression to AIDS in long-term survivors of HIV-1 infection, HIV-1-specific T cell-mediated responses, together with T cell reactivity to recall antigens, were studied in frozen samples collected after 5 and 8 years of documented HIV-1 infection. Eight of 21 homosexual men, who remained asymptomatic and maintained CD4+ T cell numbers >400 cells/microl for 9 years of HIV-1 infection, progressed to AIDS (CDC 1993 definition) within 12.5 years of infection (late progressors, LPs). The remainders showed minimal deterioration of immune parameters (long-term nonprogressors, LTNPs). CD4+ T cell numbers and T cell function measured at years 5 and 8 of follow-up were comparable in the two groups. At both time points responses to recall antigens did not significantly differ between the two groups, although a significant decline of lymphoproliferative responses to Candida and tetanus toxoid was observed in LPs. Circulating HIV-1-specific cytotoxic T lymphocyte precursors were found in broad frequency ranges in both LPs and LTNPs and, similarly, no significant differences were found in comparing the breadth of serum neutralizing activity against heterologous HIV-1 primary isolates. In contrast, lymphoproliferative responses to p24gag, but not p17gag or gp160env, were detected only in LTNPs and were totally absent in LPs at both time points (p < 0.01). Our data suggest that the presence of circulating p24-specific CD4+ T cells may reflect effective viral control and be predictive of subsequent favorable clinical course in long-term asymptomatic individuals.

Specific lysis of varicella zoster virus-infected B lymphoblasts by human T cells

Epstein-Barr virus-transformed human B cells expressed cell surface varicella-zoster virus (VZV) antigens after superinfection with VZV although they did not form infectious centers in a plaque assay. The VZV-superinfected cells were lysed by autologous VZV-stimulated T-cell lines and their derivative clones. The effector cells were specific for VZV and an HLA DR antigen and were T4+. The specificity of lysis of Epstein-Barr virus-transformed, VZV-superinfected targets by prestimulated mononuclear cells in this system contrasted with the unrestricted lysis seen when the targets were VZV-infected fibroblasts.

A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Antigen-specific T-lymphocyte proliferative responses during highly active antiretroviral therapy (HAART) of HIV-1 infection

To evaluate functional T-cell recovery during combination therapy with ritonavir, lamivudine (3TC), and zidovudine (ZDV), peripheral blood mononuclear cells (PBMC) were obtained from 4 HIV-1 infected patients (baseline values: 40 403 CD4+ T-cells/microl; 4.6-6.4 log HIV-1 RNA copies/ml) before HAART administration (week -1) and after 5, 20, and 37 weeks of treatment on average. In vitro lymphoproliferative responses (LPR) to C. albicans, tetanus toxoid, and M. tuberculosis protein purified derivative (PPD), as recall antigens (Ag), and to recombinant HIV-1 Gag-p24 and p17 were measured by 3H-Thymidine incorporation. LPR to recall Ag, almost undetectable before therapy, appeared in all four patients during HAART soon after maximal load reduction was achieved. LPR to Gag-p17, but not to p24, became also detectable in three patients, even though remaining weak. In conclusion, improved T-lymphocyte function during HAART was achieved probably mostly as a result of lower virus inhibitory factors and cytokines.

Phase II controlled trial of post-exposure immunization with recombinant gp160 versus antiretroviral therapy in asymptomatic HIV-1-infected adults. VaxSyn Protocol Team

OBJECTIVE

To alter the natural course of HIV-1 infection by inducing or potentiating immune responses to HIV-1 envelope glycoprotein.

DESIGN

Multicentre, double-blind, three-arm, placebo-controlled study.

SETTING

Outpatients attending clinics in two University Hospitals.

PATIENTS

Ninety-nine asymptomatic HIV-1-infected adults with CD4+ T-cell counts > 400 and < 600 x 10(6)/l and no previous antiretroviral therapy were included.

INTERVENTIONS

Patients were randomly assigned to three groups treated with: (i) gp160 in alum over a 2-year period in combination with placebo for the full study duration (n = 32); (ii) gp160 in alum over a 2-year period in combination with zidovudine for the full study duration (n = 34); and (iii) alum over a 2-year period in combination with zidovudine for the full study duration (n = 33).

RESULTS

Immunotherapy was well tolerated and no significant differences in disease progression were seen in the treatment groups. The majority of patients (85%) receiving gp160 showed persistent lymphoproliferative responses to the immunogen and to a different Env antigen preparation. CD4+ cell count changes in patients receiving zidovudine alone were significantly higher than those seen in patients receiving immunotherapy alone after 1 year of treatment. Zidovudine administration was associated with initial transient reduction of plasma viraemia.

CONCLUSIONS

Prolonged immunization with a soluble HIV-1 subunit provided no benefit to asymptomatic HIV-1-infected patients and was inferior to zidovudine monotherapy. Furthermore, immunization with gp160 shortened the duration of the transient viral load reduction induced by zidovudine.

HIV-specific lymphoproliferative responses in asymptomatic HIV-infected individuals

In vitro lymphoproliferative responses to HIV-1 recombinant antigens (gp160, p24, and Rev protein) were studied in 83 patients with asymptomatic HIV-1 infection (CDC groups II and III) and circulating CD4 lymphocyte numbers > 400/mm3. Significant response to at least one of the three antigens was detected in 52.4% of the subjects, but the responses were weak, and concordance of the response to the three antigens was rare, the frequency of individuals responding to each antigen not exceeding 22.4%. Increasing frequencies of response were observed when recall antigens (tetanus toxoid and Candida albicans glycomannoprotein) (65.5%) and anti-CD3 MoAb (76.6%) were used as stimuli. Although a significant association between lymphocyte response to p24, but not gp160, and steadiness of CD4 lymphocyte numbers before the assay was observed, no predictive value for lack of CD4 cell decrease was confirmed for either antigen, and fluctuation of the responses to HIV antigens was seen during subsequent follow up. The panel of T cell assays used could be regarded as appropriate for monitoring both HIV-specific responses and T lymphocyte function during immunotherapy with soluble HIV antigens.

Suppression of hepatitis B virus replication mediated by hepatitis A-induced cytokine production

BACKGROUND

Acute hepatitis A virus (HAV) infection can cause severe hepatitis especially in patients with underlying chronic liver disease. In patients with pre-existing chronic hepatitis B (HBV) acute HAV infection can suppress HBV replication. The exact mechanism of HBV suppression during acute HAV infection is still a subject of debate. One mechanism may be the production of HAV infection-induced cytokines leading to suppression of HBV replication and viral clearance.

AIM

To evaluate cytokine production and HBV-specific lympho-proliferative responses (LPR) during acute HAV infection in a patient with chronic HBV infection-clearing markers of active HBV replication.

DESIGN

Early detection of a case of acute HAV infection in an HBeAg-positive, HBV DNA-positive chronic HBV patient treated with lamivudine.

RESULTS

At the time of HAV infection a sharp peak in the gamma-interferon (IFN-gamma) level occurred just before the rise in serum transaminase activity. This was subsequently followed by a decrease in HBV DNA and HBeAg below the limit of detection of the assay. However the HBV-specific T-cell response was not modified. After resolution of the acute HAV infection and withdrawal of antiviral therapy HBV replication relapsed.

CONCLUSION

The sharp rise in IFN-gamma production mediated by the acute HAV infection may be pivotal in the suppression of HBV replication in chronic hepatitis B.

Kinetics of immune functions and virus replication during HIV-1 infection

INTRODUCTION

Kinetics of human immunodeficiency virus type 1 (HIV-1) cytotoxic T lymphocyte (CTL) responses and viral load were evaluated in HIV-1 infected homosexual men who progressed to AIDS within 3-6 years after seroconversion and in long-term survivors who remained AIDS-free for > 9 years with normal CD4+ T cell counts.

METHODS

CTL against four major HIV-1 gene products (i.e. Gag, reverse transcriptase (RT), Nef and Env) were expanded in vitro under limiting dilution conditions using antigen specific stimulation. CTL activity was measured in standard split-well 51Cr-release assay. Viral load was measured both as serum HIV-1 RNA levels and frequency of circulating CD4+ T cells productively infected with HIV-1. Polyclonal T cell function in vitro was determined in whole blood lymphocyte cultures, measuring lymphoproliferative responses to CD3 monoclonal antibody.

RESULTS

Long-term survival was associated with either persistently high or stable low HIV-1 specific CTL responses, accompanied by preserved in vitro polyclonal T cell reactivity and low viral load. In progressors, HIV-1 specific CTL responses were initially generated with similar kinetics as compared to long-term survivors. However, with progression to AIDS antiviral CTL activity and T cell function deteriorated simultaneously, while viral load increased.

CONCLUSIONS

Our results are consistent with the hypothesis that HIV-1 specific CTL are beneficial through control of viremia to the virologic set-point and contribute to maintenance of the asymptomatic phase. However, loss of HIV-1 specific immune control as part of a more general loss of T cell function is the precipitating event in AIDS pathogenesis.

Detection and partial characterization of circulating immune complexes in hydatid disease

Thirty sera from eight patients with disseminated or localized hydatid disease have been examined for the presence of circulating immune complexes (CICs) by the conglutinin-binding assay and for immunoglobulin levels. The highest levels of CICs were of the immunoglobulin A (IgA) class, with lower values of IgG-CIC and IgM-CIC; these results did not correlate, except for IgG, with the free immunoglobulin levels. Efforts to identify parasitic antigen(s) involved in the CIC formation with different methods have been unsuccessful. In the follow-up of each patient, CIC appeared to be better correlated to clinical conditions than to hemagglutination titers. We have concluded that the presence of CIC in hydatid disease is probably an expression of B-cell polyclonal activation and that these complexes are valuable in the clinical monitoring of the disease.

IgG anti-IgE in circulating immune complexes in the hyper-IgE syndrome

We fractionated, by gel chromatography, sera with high IgE content from atopic subjects and five cases with the hyper-IgE syndrome, and measured the presence of IgE in high molecular weight (HMW) fractions. Two out of four asthmatics and four out of five hyper-IgE had HMW IgE. The same serum fractions gave positive results for conglutinin binding IgG (all six) and IgA (three cases) as well as C1q binding complexes (five cases). IgG auto-antibodies to IgE were also detected together with IgE in HMW fractions. Anti-F(ab)'2 activity was present in five cases (one of them negative for IgG anti-IgE). Our data indicate that complexes made of IgE and IgG anti-IgE are present mainly in patients with chronic allergic symptoms and most frequent in cases of hyper-IgE syndrome.

In vitro use of autologous dendritic cells improves detection of T cell responses to hepatitis B virus (HBV) antigens

T lymphocyte responses to hepatitis B virus (HBV) core antigen (HBcAg) are vigorous and easily detectable in vitro during recovery from acute hepatitis B but significantly weaker in patients with chronic HBV infection. In contrast, T cell responses to hepatitis B surface antigen (HBsAg) are almost undetectable during infection and even in a substantial fraction of subjects receiving vaccination with HBsAg. The aim of this study was to investigate whether the use of dendritic cells (DCs) in an in vitro assay could increase the detection of HBV-specific T cells in these conditions. Autologous monocyte-derived DCs, compared to direct HBsAg addition to the cultures, increased the stimulation of HBs- specific T cells. These were detected in 73% of healthy subjects who had recently received hepatitis B vaccine and in 43% of patients recovering from acute hepatitis B. Likewise, proliferation in response to DC-presented HBcAg was detected in both CD4(+) and CD8(+) T cells from the majority of chronic hepatitis B patients. A longitudinal evaluation of HBc-specific T cell responses during and after a 1-year treatment with pegylated interferon (IFN)-alpha showed that HBc-specific CD4(+) T cell responses had no correlation with sustained virus suppression whereas CD8(+) T cell responses were more frequently detected in patients able to control HBV replication after therapy interruption. The use of autologous DCs as antigen-presenting cells appears applicable to clinically relevant in vitro evaluation of T cell responses, particularly in those conditions characterized by low frequency of circulating antigen-specific cells and suboptimal in vivo activation.

Antiviral treatment with alpha interferon up-regulates CD14 on liver macrophages and its soluble form in patients with chronic hepatitis B

To investigate whether therapy with alpha interferon (IFN-alpha) induces changes in intrahepatic antigen-presenting cells (APCs), we obtained liver biopsy specimens before, during, and after therapy with IFN-alpha from chronic hepatitis B patients whose viral load had already been reduced by at least 8 weeks of treatment with lamivudine. HLA-DR, CD1a, and CD83 were not modified by the therapy. The intralobular expression of CD68 on Kupffer cells remained stable, denoting no changes in the number of resident macrophages during IFN-alpha treatment. In contrast, CD14 was weakly expressed in the absence of IFN-alpha and was significantly up-regulated during therapy. At the same time, the levels of soluble CD14 and interleukin-10 in plasma increased significantly. In vitro, monocytes maintained in the presence of IFN-alpha differentiated into macrophages or dendritic cells with higher levels of expression of CD14 than that for the control cultures. During therapy with IFN-alpha, T-cell infiltration in the portal spaces was reduced, mainly due to a significant decrease in the number of CD8(+) T cells. These findings show that IFN-alpha is biologically active on APCs in vivo and in vitro and suggest that this newly described regulatory function, together with the already known inhibitory effects on lymphocytes, may cooperate to reduce inflammation and consequent tissue damage in patients with chronic viral hepatitis.

Hepatitis B virus-specific T cell response in chronic hepatitis B patients treated with lamivudine and interferon-alpha

AIMS

The goal of the present study was to assess the impact combination antiviral therapy has on immune responses in chronic hepatitis B.

MATERIALS AND METHODS

T cell responses were studied in 16 chronically hepatitis B virus (HBV)-infected patients treated with sequential, partially overlapping, lamivudine-interferon (IFN)-alpha combination therapy.

RESULTS

HBcAg-specific lymphoproliferative response (LPR) was transiently detected in four of five patients who achieved virus suppression (HBV DNA < 10(4) genome equivalents/ml) at end of dual therapy, and then reverted to pre-treatment viral load after therapy discontinuation. In contrast, no significant HBcAg-specific LPR was detected in 8 patients who did not attain profound HBV suppression, as well as in three patients who experienced no HBV DNA rebound after therapy discontinuation.

CONCLUSIONS

This pilot study suggests that restored viral replication after pharmacological suppression drives the immune response to HBV in chronically infected patients. Further characterization of the adaptive immunity and its regulatory mechanisms at time of therapy discontinuation appears therefore necessary in controlled trials.

Reciprocal changes of naïve and effector/memory CD8+ T lymphocytes in chronic hepatitis B virus infection

Persistent viruses, such as cytomegalovirus or human immunodeficiency virus, cause major perturbations of CD8+ T-lymphocyte subpopulations. To test whether chronic infection with hepatitis B virus (HBV) could also be responsible for such modifications, we analyzed the expression of CD27, CD28, CCR7, and perforin in blood CD8+ T lymphocytes. In comparison to healthy subjects and patients recovering from acute hepatitis B, chronic hepatitis B patients showed higher percentages of naïve CD8+ T lymphocytes (CD45RA+CD27+CD28+), and lower percentages of intermediately-differentiated CD27+CD28⁻CD8+ T cells. The late differentiated CD45RA+CD27⁻CD28⁻ subset was also present in a large percentage in some patients, but no statistically significant difference with healthy controls was observed. Removal from the circulation of intermediately-differentiated CD8+ T lymphocytes may occur during chronic HBV infection, favoring the recruitment of naïve cells. This may result in impairment of the generation of functionally-competent memory cells, and an inability to achieve control of HBV replication.

CD28 costimulation and T lymphocyte proliferative responses in HIV-1 infection

To investigate whether defective costimulatory signals could be involved in the loss of T lymphocyte functions during HIV-1 infection, we tested the effect of CD28 costimulation on both T cell receptor/CD3 and HIV-1 antigen-induced proliferative responses. Although CD3-mediated responses significantly decreased with more advanced stages of HIV-1 infection, the ability of potentiating the responses through CD28 costimulation was maintained at all stages and did not differ from that of HIV-1- subjects. When CD28 costimulation was studied in lymphocyte cultures stimulated with HIV-1 gp160 or p24, potentiation was seen only when a significant response was present without additional CD28 triggering, namely in subjects receiving active immunization with recombinant gp160. These results confirm the integrity of the CD28 pathway of costimulation during HIV-1 infection, and suggest that lymphocytes responding to soluble HIV-1 antigen are not deleted in HIV-1-infected patients, but do not receive significant priming during the natural course of the infection.