Functional restoration of human immunodeficiency virus and Epstein-Barr virus-specific CD8(+) T cells during highly active antiretroviral therapy is associated with an increase in CD4(+) T cells

Direct intranodal tonsil vaccination with modified vaccinia Ankara vaccine protects macaques from highly pathogenic SIVmac251

Human immunodeficiency virus (HIV) is a mucosally transmitted virus that causes immunodeficiency and AIDS. Developing efficacious vaccines to prevent infection is essential to control the epidemic. Protecting the vaginal and rectal mucosa, the primary routes of HIV entry has been a challenge given the significant compartmentalization between the mucosal and peripheral immune systems. We hypothesized that direct intranodal vaccination of mucosa associated lymphoid tissue (MALT) such as the readily accessible palatine tonsils could overcome this compartmentalization. Here we show that rhesus macaques primed with plasmid DNA encoding SIVmac251-env and gag genes followed by an intranodal tonsil MALT boost with MVA encoding the same genes protects from a repeated low dose intrarectal challenge with highly pathogenic SIVmac251; 43% (3/7) of vaccinated macaques remained uninfected after 9 challenges as compared to the unvaccinated control (0/6) animals. One vaccinated animal remained free of infection even after 22 challenges. Vaccination was associated with a ~2 log decrease in acute viremia that inversely correlated with anamnestic immune responses. Our results suggest that a combination of systemic and intranodal tonsil MALT vaccination could induce robust adaptive and innate immune responses leading to protection from mucosal infection with highly pathogenic HIV and rapidly control viral breakthroughs.

Comparing the sub-gingival levels of Cytomegalovirus, Epstein-Barr virus, Porphyromonas gingivalis in human immunodeficiency virus-1 seropositive patients with and without antiretroviral therapy

OBJECTIVES

The effect of antiretroviral therapy (ART) on the oral pathogenic microbes in human immunodeficiency virus-1 seropositive patients remains relatively unexplored. Thus, the present study assessed the effect of ART on the sub-gingival levels of 3 pathogenic microbes.

MATERIALS AND METHODS

The study groups consisted of 60 human immunodeficiency virus-1 seropositive patients divided into 3 groups of 20 each. Group 1 had periodontitis and did not start with the ART. Group 2 had periodontitis and started with ART (Tenofovir Disoproxil Fumarate 300 mg + Lamivudine 300 mg + Efavirenz 600 mg) at least 6 months before the study. Group 3 with normal periodontium, and have not started ART. The sub-gingival loads of Cytomegalovirus, Epstein-Barr virus, and the Porphyromonas gingivalis levels were assessed, along with the CD4 counts.

RESULTS

The cytomegalovirus load was highest in group 1, followed by groups 2, and 3 (p-value of 0.271). The Epstein-Barr load was highest for group 2, followed by group 3, and 1 (p-value of 0.022). The P.gingivalis load was highest in group 2, followed by groups 1 and 3, (p-value of 0.028). The Epstein-Barr and Cytomegalovirus counts were significantly higher (p-value < 0.02) when the CD4 counts were less than 500 cells/cu3.

CONCLUSION

ART did not cause any significant reduction in the sub-gingival levels of any of the 3 examined microbes. Given the lack of any significant effect on the sub-gingival microbial loads by the ART, human immunodeficiency virus patients may require additional anti-microbial agents and regular mechanical plaque removal to maintain their periodontal status.

Serological Assessment of 18 Pathogens and Risk of AIDS-Associated Non-Hodgkin Lymphoma

BACKGROUND

HIV infection is associated with increased susceptibility to common pathogens, which may trigger chronic antigenic stimulation and hyperactivation of B cells, events known to precede the development of AIDS-associated non-Hodgkin lymphoma (AIDS-NHL).

METHODS

To explore whether cumulative exposure to infectious agents contributes to AIDS-NHL risk, we tested sera from 199 AIDS-NHL patients (pre-NHL, average lead time 3.9 years) and 199 matched HIV-infected controls from the Multicenter AIDS Cohort Study, for anti-IgG responses to 18 pathogens using multiplex serology. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression models.

RESULTS

We found no association between cumulative exposure to infectious agents and AIDS-NHL risk (OR 1.01, 95% CI: 0.91 to 1.12). However, seropositivity for trichodysplasia spinulosa polyomavirus (TSPyV), defined as presence of antibodies to TSPyV capsid protein VP1, was significantly associated with a 1.6-fold increase in AIDS-NHL risk (OR 1.62, 95% CI: 1.02 to 2.57). High Epstein-Barr virus (EBV) anti-VCA p18 antibody levels closer to the time of AIDS-NHL diagnosis (<4 years) were associated with a 2.6-fold increase in AIDS-NHL risk (OR 2.59, 95% CI: 1.17 to 5.74). In addition, high EBV anti-EBNA-1 and anti-ZEBRA antibody levels were associated with 2.1-fold (OR 0.47, 95% CI: 0.26 to 0.85) and 1.6-fold (OR 0.57, 95% CI: 0.35 to 0.93) decreased risk of AIDS-NHL, respectively.

CONCLUSIONS

Our results do not support the hypothesis that cumulative exposure to infectious agents contributes to AIDS-NHL development. However, the observed associations with respect to TSPyV seropositivity and EBV antigen antibody levels offer additional insights into the pathogenesis of AIDS-NHL.

National Institutes of Health Hematopoietic Cell Transplantation Late Effects Initiative: The Immune Dysregulation and Pathobiology Working Group Report

Immune reconstitution after hematopoietic stem cell transplantation (HCT) beyond 1 year is not completely understood. Many transplant recipients who are free of graft-versus-host disease (GVHD) and not receiving any immunosuppression more than 1 year after transplantation seem to be able to mount appropriate immune responses to common pathogens and respond adequately to immunizations. However, 2 large registry studies over the last 2 decades seem to indicate that infection is a significant cause of late mortality in some patients, even in the absence of concomitant GVHD. Research on this topic is particularly challenging for several reasons. First, there are not enough long-term follow-up clinics able to measure even basic immune parameters late after HCT. Second, the correlation between laboratory measurements of immune function and infections is not well known. Third, accurate documentation of infectious episodes is notoriously difficult. Finally, it is unclear what measures can be implemented to improve the immune response in a clinically relevant way. A combination of long-term multicenter prospective studies that collect detailed infectious data and store samples as well as a national or multinational registry of clinically significant infections (eg, vaccine-preventable severe infections, opportunistic infections) could begin to address our knowledge gaps. Obtaining samples for laboratory evaluation of the immune system should be both calendar and eventdriven. Attention to detail and standardization of practices regarding prophylaxis, diagnosis, and definitions of infections would be of paramount importance to obtain clean reliable data. Laboratory studies should specifically address the neogenesis, maturation, and exhaustion of the adaptive immune system and, in particular, how these are influenced by persistent alloreactivity, inflammation, and viral infection. Ideally, some of these long-term prospective studies would collect information on long-term changes in the gut microbiome and their influence on immunity. Regarding enhancement of immune function, prospective measurement of the response to vaccines late after HCT in a variety of clinical settings should be undertaken to better understand the benefits as well as the limitations of immunizations. The role of intravenous immunoglobulin is still not well defined, and studies to address it should be encouraged.

Acute HIV infection: it takes more than guts

PURPOSE OF REVIEW

To understand the cellular and molecular mechanisms of acute HIV pathogenesis.

RECENT FINDINGS

Recent studies have given us new insights into the mechanisms of acute HIV pathogenesis by demonstrating the 'systemic' destruction of the CD4 memory T cell compartment. This destruction occurs well before the emergence of a strong and broad immune response, highlighting the failure of the immune response to contain early viral infection and destruction. However, recent data also suggest that very few founder populations of cells are infected early, at the portal of entry, making them ideal targets for vaccine-induced immune responses that may aid in the effective control of early infection and transmission.

SUMMARY

HIV causes a massive destruction of memory CD4 T cells during the early acute phase of infection. This destruction proceeds largely in the absence of emerging antiviral immune responses, and severely disables the ability of the immune system to generate secondary immune responses. Early preservation of the memory CD4 compartment by shifting emphasis of antiretroviral therapeutic strategies to early treatment, and development of vaccines that can induce strong and broad immune responses, will be critical to prevent the destructive effects of early HIV infection.

Influence of HIV infection on cytomegalovirus-specific immunity: T-cell responses to pp65 and IE1 before and after HAART may reflect altered cytomegalovirus biology

BACKGROUND

Data are inconclusive whether treatment with HAART induces functional recovery of HIV-specific T-cells. Since the introduction of HAART, a marked decrease of cytomegalovirus (CMV) disease - for which untreated HIV-infected individuals are at increased risk - is observed, suggesting that this treatment influences CMV-specific T-cell immunity.

METHODS

To study potential functional recovery of HIV- and CMV-specific T-cells, CD4(+) and CD8(+) T-cell responses were measured longitudinally after in vitro expansion using gag, pp65 and IE1 peptide pools, during HIV infection and after long-term HAART.

RESULTS

HIV-specific T-cell function, measured by interferon (IFN)-γ production, was low after initiation of HAART. Interestingly, the cytotoxic function - measured by CD107a expression - of these T-cells temporarily increased after start of treatment, suggesting some functional recovery. The pp65-specific CD8(+) T-cell responses tended to decrease during HIV infection, whereas pp65-specific CD4(+) T-cell responses decreased upon treatment with HAART. Both pp65-specific CD4(+) and CD8(+) T-cell responses were low after initiation of HAART compared to healthy controls. By contrast, IE1-specific CD4(+) T-cell responses increased during the course of HIV infection. After initiation of HAART, IE1-specific T-cell responses decreased, but IE1-specific CD8(+) T-cells seemed increased compared to healthy controls.

CONCLUSIONS

This study suggests that HIV-infection leads to an altered CMV biology, affecting pp65- and IE1-specific T-cell responses in a different way, which is not restored by treatment with long-term HAART.

Antiretroviral therapy-induced dominant interleukin-2 HIV-1 Gag CD4+ T cell response: evidence of functional recovery of HIV-1-specific CD4+ T cells

Prolonged antiretroviral treatment (ART) significantly changes the cytokine secretion capacities of HIV-1-specific T cells. However, it is unclear whether these changes result from decreased viremia or they correspond to true functional recovery of viral-specific immune response. To study this issue, we analysed the quantitative and qualitative differences of HIV-1-specific and polyclonal CD4+ and CD8+ T cells between 26 naive and 52 treated individuals. HIV-1 Gag and staphylococcal enterotoxin B (SEB)-reactive T cells were determined by flowcytometric intracellular secretion of IFN-γ or/and ΙL-2. ART resulted in increase of single IL-2 and decrease of single IFN-γ-secreting HIV-1 CD4+ T cells, while both cytokines secreting HIV-1 CD4+ T cells were presented in comparable frequencies in both groups. Viral loads correlated negatively with single IL-2 and positively with single IFN-γ-secreting HIV-1 CD4+ cells. Single IL-2 HIV-1 CD4+ T cells correlated positively with both cytokines secreting polyclonal CD8+ T cells. By qualitative analysis, a dominant IL-2 HIV-1 CD4+ T cell response (> 70% single IL-2) was identified only in ART suppressed patients, who also generated increased dual specific polyclonal CD8+ T cells. Polyfunctional HIV-1 CD4+ T cell responses were detected even in naive individuals with high viremia. In conclusion, the presence of dominant IL-2 HIV-1 CD4+ T cell response, associated with increased CD8+ T cells capable to produce IL-2, indicates that the recovery of HIV-1-specific CD4+ T cell functionality under ART is a feasible goal. Furthermore, polyfunctional HIV-1 CD4+ T cell responses seem not to be directly involved in viral replication control.

Immunological analysis of treatment interruption after early highly active antiretroviral therapy

We longitudinally evaluated HIV-specific T-cell immunity after discontinuation of highly active antiretroviral therapy (HAART). After treatment interruption (TI), some individuals could maintain a low plasma viral load (<15,000 copies/mL), whereas others could not (>50,000 copies/mL). Before HAART was initiated, plasma viral load was similar. After TI, the numbers of CD8(+) T cells increased more in individuals without viral control, whereas individuals maintaining a low viral load showed a more pronounced increase in HIV-specific CD8(+) T-cell numbers. No differences were seen in the number or percentage of cytokine-producing HIV-1-specific CD4(+) T cells, or in proliferative capacity of T cells. Four weeks after TI, the magnitude of the total HIV-1-specific CD8(+) T-cell response (IFN-γ(+) and/or IL-2(+) and/or CD107a(+)) was significantly higher in individuals maintaining viral control. Degranulation contributed more to the overall CD8(+) T-cell response than cytokine production. Whether increased T-cell functionality is a cause or consequence of low viral load remains to be elucidated.

Epstein-Barr virus (EBV) gene expression in interstitial pneumonitis in Brazilian human immunodeficiency virus-1-infected children: is EBV associated or not?

To gain further knowledge on the subject we evaluated Epstein-Barr virus (EBV) gene expression and TCD4+, TCD8+, and B lymphocyte counts in lung tissue samples from 20 human immunodeficiency virus (HIV)-infected children with chronic lung disease. Twenty HIV-1 infected children with chronic pulmonary disease underwent open lung biopsy to define the diagnosis. Histological section of this material was submitted to nonisotopic in situ hybridization (ISH) using EBV-encoded RNA (EBER) 1/2 probes and TCD4+, TCD8+, and CD20+ B-cell counts by immunohistochemistry. The histology of 16 out of the 20 children (median age 53.5 months) proved to be examples of pulmonary lymphoid hyperplasia/lymphoid interstitial pneumonitis (PLH/LIP) complex, 13 of which were EBER positive, but no significant association was found (Fisher exact test P = 0.439). Four patients had non-LIP diseases (3, nonspecific interstitial pneumonia; 1, diffuse advanced alveolar damage), two being EBER negative. Nineteen children showed a predominant T-CD8+ cell response (CD4+/CD8+ <1) in lung tissue. The mean TCD4+ and theTCD4/TCD8 ratio in lung tissue were significantly higher in the sections with PLH/LIP complex, but without significant difference between EBER positive and EBER negative samples. EBV gene expression was detected in the majority of the lung samples but without significant association with PLH/LIP complex or with TCD4+, TCD8+, B cells and the TCD4+/TCD8+ ratio. Regarding the pattern of lung disease in HIV-1 infected children, associated or not to EBV, the findings are of importance concerning the possible role of EBV in the pathogenesis of PLH/LIP.

The Effect of Antiretroviral Combination Treatment on Epstein-Barr Virus (EBV) Genome Load in HIV-Infected Patients

We evaluated the effect of combination anti-retroviral treatment (cART) on the host control of EBV infection in moderately immunosuppressed HIV-1 patients. Twenty HIV-1 infected individuals were followed for five years with repeated measurements of EBV DNA load in peripheral blood lymphocytes in relation to HIV-RNA titers and CD4+ cell counts. Individuals with optimal response, i.e. durable non-detectable HIV-RNA, showed a decline of EBV load to the level of healthy controls. Individuals with non-optimal HIV-1 control did not restore their EBV control. Long-lasting suppression of HIV-replication after early initiation of cART is a prerequisite for re-establishing the immune control of EBV.

CTL fail to accumulate at sites of HIV-1 replication in lymphoid tissue

The inability of HIV-1-specific CTL to fully suppress virus replication as well as the failure of administration of exogenous CTL to lower viral loads are not understood. To evaluate the hypothesis that these phenomena are due to a failure of CTL to localize at sites of HIV-1 replication, we assessed the distribution of HIV-1 RNA and HIV-1-specific CTL identified by HIV-1 peptide/HLA class I tetrameric complexes (tetramers) within lymph nodes of 14 HIV-1-infected individuals who were not receiving antiretroviral therapy. A median of 0.04% of follicular compared with 0.001% of extrafollicular CD4(+) cells were estimated to be producing HIV-1 RNA, a 40-fold difference (p = 0.0001). Tetramer-stained cells were detected by flow cytometry in disaggregated lymph node cells from 11 subjects and constituted a significantly higher fraction of CD8(+) cells in lymph node (mean, 2.15%) than in PBMC (mean, 1.52%; p = 0.02). In situ tetramer staining in three subjects' lymph nodes, in which high frequencies of tetramer-stained cells were detected, revealed that tetramer-stained cells were primarily concentrated in extrafollicular regions of lymph node and were largely absent within lymphoid follicles. These data confirm that HIV-1-specific CTL are abundant within lymphoid tissues, but fail to accumulate within lymphoid follicles where HIV-1 replication is concentrated, suggesting that lymphoid follicles may be immune-privileged sites. Mechanisms underlying the exclusion of CTL from lymphoid follicles as well as the role of lymphoid follicles in perpetuating other chronic pathogens merit further investigation.

Association of human leukocyte antigen haplotypes with posttransplant lymphoproliferative disease after solid organ transplantation

BACKGROUND

Posttransplant lymphoproliferative disease (PTLD) after solid organ transplantation (SOT) is commonly characterized by Epstein-Barr virus (EBV)-driven proliferation of recipient B cells due to impaired immune surveillance in the context of immunosuppression. Because EBV-specific T-cell responses are focused on the level of EBV antigen and epitope choice depending on the individual human leukocyte antigen (HLA) alleles, we hypothesized that certain HLA alleles or a distinct HLA haplotype may influence the risk of development of PTLD after SOT.

METHODS

A multicenter case-control study was performed comparing a group of 155 recipients after SOT with development of PTLD with a group of 1996 recipients after SOT without development of PTLD. Alleles, genotypes, and three locus haplotypes were compared of SOT recipients with and without PTLD.

RESULTS

The bivariate analysis showed that carrying HLA-A03 was negatively associated (odds ratio [OR] 0.61, confidence interval [CI] 0.40-0.92, P < 0.02) whereas carrying of HLA-B18 (OR 1.79, CI 1.18-2.73, P < 0.006) and HLA-B21 (OR 2.08, CI 1.14-3.77, P < 0.02) were positively associated with PTLD after SOT. HLA-DR analysis demonstrated a significant negative association between the expression of HLA-DR7 (OR 0.46, CI 0.28-0.78, P < 0.004) and PTLD. Three locus haplotype analysis underlined the relevance of a dominant protective effect of HLA-DR7 expression concerning the risk of PTLD development.

CONCLUSIONS

Our data suggest an influence of HLA variants on the risk of the development of PTLD. We hypothesize that HLA genes or non-HLA genes within the HLA loci confer a risk modification for the individual patient.

Vaccination preserves CD4 memory T cells during acute simian immunodeficiency virus challenge

Acute simian immunodeficiency virus (SIV)/human immunodeficiency virus infection is accompanied by a massive destruction of CD4 memory T cells across all the tissue compartments. These early events set the course toward disease progression and immunodeficiency. Here, we demonstrate that prior vaccination reduces this destruction during acute SIV Mac251 infection, leading to better survival and long-term outcome. Systemic vaccination with a DNA-prime recombinant adenovirus boost regimen preserved memory CD4 T cells throughout the body. The vaccine regimen induced broad CD4 and CD8 T cell responses in all tissues examined and, importantly, induced antibodies that neutralized the primary isolate of SIV used for challenge. Finally, we demonstrate that the extent of preservation of the CD4 memory compartment during the acute phase provides a strong predictor for subsequent progression to death. Our data provide a mechanism to explain clinical observations that acute-phase viral loads predict long-term disease progression and underscore the need for interventions that protect against early destruction of CD4 memory T cells during acute infection.

Long-Term Highly Active Antiretroviral Therapy in Chronic HIV-1 Infection: Evidence for Reconstitution of Antiviral Immunity

In this study we investigated the long-term effect of highly active antiretroviral therapy (HAART) on HIV-specific CD4+ T-cell responses in comparison with virus-specific CD4+ T-cell responses against the persistent herpes viruses cytomegalovirus (CMV) and Epstein-Barr virus (EBV). To this end, HIV- and herpes virus-specific cellular immune responses were measured longitudinally in 10 seroconverters with long-term follow-up including 55 months of successful suppression of viral load by HAART. HIV- and CMV-specific CD4+ T cells producing interferon-γ (IFNγ) or interleukin-2 (IL-2) were analysed as well as proliferative capacity. EBV-specific CD4+ T cells were determined using a 12-day ex vivo assay. Initiation of HAART resulted in a transient increase of HIV-specific IL-2+IFNγ+CD4+ T cells and, to a lesser extent, IL-2+CD4+ T cells. Long-term HAART resulted in an increase in HIV-, CMV- and EBV-specific CD4+ T-cell proliferative capacity. The increase in HIV- and herpes-virus-specific CD4+ T-cell proliferative capacity after 55 months of HAART suggests that the improved proliferative response is not specific for HIV, but reflects a more general improvement of antiviral immune responses, which is induced by HAART.

Natural controlled HIV infection: preserved HIV-specific immunity despite undetectable replication competent virus

Long-term non-progressive HIV infection, characterized by low but detectable viral load and stable CD4 counts in the absence of antiviral therapy, is observed in about 5% of HIV-infected patients. Here we identified four therapy naïve individuals who are strongly seropositive for HIV-1 but who lack evidence of detectable HIV p24 antigen, plasma RNA, and proviral DNA in routine diagnostic testing. With an ultrasensitive PCR, we established that frequencies of pol proviral DNA sequences were as low as 0.2-0.5 copies/10(6) PBMC. HIV could not be isolated using up to 30x10(6) patient PBMC. One individual was heterozygous for CCR5 Delta32, but CCR5 expression on CD4+ T cells was normal to high in all four individuals. In vitro R5 and X4 HIV-1 susceptibility of CD8-depleted PBMC of all study subjects was significantly lower than the susceptibility of CD8-depleted PBMC of healthy blood donors. All individuals expressed protective HLA-B*58s alleles and showed evidence of HIV-specific cellular immunity either by staining with HLA-B*57 tetramers folded with an HIV RT or gag peptide or after stimulation with HIV-1 p24 gag, RT, or nef peptides in ELIspot analysis. HIV-specific CD4+ T helper cells were demonstrated by proliferation of CD4+ T cells and intracellular staining for IL-2 and IFNgamma after stimulation with an HIV-gag peptide pool. Sera of all individuals showed antibody-mediated neutralization of both R5 and X4 HIV-1 variants. These data implicate that very low-level antigen exposure is sufficient for sustained HIV-specific immunity and suggest the possibility of a multi-factorial control of HIV infection.

Reconstitution of EBV Latent but Not Lytic Antigen-Specific CD4+and CD8+T Cells after HIV Treatment with Highly Active Antiretroviral Therapy

The incidence of (EBV-related) malignancies in HIV-infected subjects has declined since the introduction of highly active antiretroviral therapy (HAART). To investigate the effect of HAART on EBV infection, we performed a longitudinal analysis of the T cell response to both a latent and a lytic Ag and EBV viral load in 10 subjects from early in HIV infection up to 5 years after HAART. All individuals responded to HAART by a decline in HIV viral load, a restoration of total CD4+ T cell numbers, and a decline in T cell immune activation. Despite this, EBV load remained unaltered, even after 5 years of therapy, although a decline in both CD4+ and CD8+ T cells specific for the lytic EBV protein BZLF1 suggested a decreased EBV reactivation rate. In contrast, latent EBV Ag EBNA1-specific CD4+ and CD8+ T cell responses were restored after 5 years of treatment to levels comparable to healthy individuals. In two individuals who were treated by HAART late during HIV progression, a lymphoma developed shortly after initiation of HAART, despite restoration of EBV-specific CD4+ and CD8+ T cells. In conclusion, long-term HAART does not alter the EBV DNA load, but does lead to a restoration of EBNA1-specific T cell responses, which might allow better control of EBV-infected cells when applied early enough during HIV infection.

Analysis of antigen-specific T-cell responses with synthetic peptides--what kind of peptide for which purpose?

The analysis of T-cell responses to peptides has recently become a busy area of immunologic research. Peptides may be used as single stimulants, pools or libraries, or as part of peptide/major histocompatibility complexes (MHC) for direct T-cell receptor staining. For stimulating T cells, peptides must be bound to MHC molecules. In this study we have used 9- or 10-amino acid peptides, 15-amino acid peptides containing stimulating shorter sequences, and peptides with modified C-terminal function. On average 67% of the T cells from healthy cytomegalovirus-positive donors that bound a frequently used cytomegalovirus pp65/HLA-A*0201 tetramer were able to produce interferon-gamma on stimulation with the respective 9-amino acid peptide. Peptides of 15 amino acids length used at the same concentration (in microg/ml) stimulated CD8 T cells somewhat less efficiently (on average 77% of the frequencies induced with the respective shorter peptides). Modifications of 9-amino acid peptides such as addition of amino acids or functional groups often resulted in a decreased ability to stimulate. However, based on our own results, published data, and theoretic considerations, we conclude that sets of peptides of 15 amino acids length with 11 amino acids overlap represent a good compromise for stimulating both CD8 and CD4 T cells in a number of applications. These parameters may be modified subject to the purpose of a study.

High responsiveness of HLA-B57-restricted Gag-specific CD8+ T cells in vitro may contribute to the protective effect of HLA-B57 in HIV-infection

HLA-B57 has been shown to be associated with long-term asymptomatic HIV-1 infection. To investigate the biological mechanism by which the HLA-B57 allele could protect from HIV-1 disease, we studied both the number of CD8(+) T cells as well as CD8(+) T cell responsiveness directed to different HIV-1 Gag peptides presented by HLA-A2, -B8 or -B57. T cells specific for the HLA-B57 peptide KAFSPEVIPMF responded more readily and to a higher extend to antigenic stimulation in vitro than T cells specific for the HLA-A2 peptide SLYNTVATL or the HLA-B8 peptide EIYKRWII. This phenomenon was reproducible with T cells from individuals expressing HLA-B57 in combination with one or both of the other alleles and was persistent during long-term follow-up. Lower reactivity of A2- and B8-restricted T cells was not explained by mutations in the B8- or A2-restricted Gag-peptides. Moreover, no correlation between peptide mutation frequency and IFN-gamma production by the corresponding Gag-specific T cells was observed. In conclusion, functional differences were observed between T cells specific for HIV epitopes derived from the same protein presented by different HLA molecules. B57-restricted KAFSPEVIPMF-specific CD8(+) T cells have relatively high responsiveness, which could contribute to the protective effect of HLA-B57 in HIV infection.

The magnitude and breadth of hepatitis C virus–specific CD8+ T cells depend on absolute CD4+ T-cell count in individuals coinfected with HIV-1

CD8+ T-cell responses are an essential antiviral host defense in persistent viral infections, and their sustained effectiveness is thought to be critically dependent on CD4+ T-helper cells. To determine the relationship between HIV-1–induced CD4+ T-cell depletion and hepatitis C virus (HCV)–specific CD8+ T-cell responses during viral persistence, we studied 103 persons positive for HCV, 74 coinfected with HIV-1. CD8+ T-cell responses to the entire HCV polyprotein were determined by using an interferon-γ enzyme-linked immunospot (ELISpot) assay. Although HIV-1 infection by itself was not associated with a diminished HCV-specific response, HIV-1–associated CD4+ depletion was associated with significantly lower HCV-specific CD8+ T cells (R = 0.48, P &lt; .0001). In contrast, declining CD4+ counts over the same range were not associated with diminished Epstein-Barr virus (EBV)– (R = 0.19, P = .31) or HIV-1–specific (R = –0.13, P = .60) CD8+ T-cell responses in persons infected with all viruses. These data indicate that frequencies of circulating HCV-specific CD8+ T-cell responses are sensitive to absolute CD4+ T-cell counts and provide a possible explanation for the accelerated HCV disease course in persons coinfected with HIV-1 and HCV.

AIDS-related cancer in the era of highly active antiretroviral therapy (HAART): a model of the interplay of the immune system, virus, and cancer. "On the offensive--the Trojan Horse is being destroyed"--Part B: Malignant lymphoma

The impact of highly active antiretroviral therapy (HAART) on the incidence of non-Hodgkin's lymphoma was less obvious initially, although primary central nervous system lymphoma (PCNSL) has dropped precipitously since the introduction of HAART. The pathogenesis of acquired immunodeficiency syndrome-related lymphoma is multifactorial. Epstein-Barr virus plays a significant role in these diseases, especially Burkitt lymphoma and PCNSL. Data regarding the effect of HAART on the natural history and treatment outcomes of these malignancies are emerging. The possibility of direct and indirect roles of human immunodeficiency virus in the carcinogenesis suggests that antiretroviral therapy may be an important component of the treatment for these malignancies. The simultaneous administration of HAART and chemotherapy does not appear to significantly alter the toxicity profile, although the information with respect to the interaction of HAART and chemotherapy is limited. The use of biological agents, for example, monoclonal antibody against CD-20, is being explored to improve the clinical outcome of this disease.

Antitumour effects of antiretroviral therapy

Infection by human immunodeficiency virus (HIV) is associated with an increased risk of certain tumours, particularly Kaposi's sarcoma, non-Hodgkin's lymphomas and cervical cancer. However, the incidence of these tumours in HIV-infected patients has decreased significantly since the widespread use of highly active antiretroviral therapy (HAART). This effect cannot be solely explained by the ability of these drugs to suppress HIV replication and thereby reconstitute the immune system. Recent studies have shown that inhibitors of the HIV aspartyl protease, which are widely used in HAART, have direct anti-angiogenic and antitumour effects that are unrelated to their antiviral activity. So these drugs might be used to treat cancer in patients who are not infected with HIV.

Altered EBV Viral Load Setpoint after HIV Seroconversion Is in Accordance with Lack of Predictive Value of EBV Load for the Occurrence of AIDS-Related Non-Hodgkin Lymphoma

In contrast to the situation in the post-transplant setting, in HIV-infected individuals an elevated EBV load is not predictive of EBV-related malignancies. To study whether a high EBV load is already a normal situation early in HIV infection and is not related to a decrease in immune function over time, we investigated EBV load and EBV-specific CD8(+) T cells approximately 1 year before and 1 year after HIV seroconversion. EBV load significantly increased after HIV seroconversion from 205 to 1002 copies/10(6) PBMC (p < 0.001), whereas no further increase in EBV load was observed between 1 and 5 years after HIV seroconversion (median, 1827-2478 copies/10(6) PBMC; p = 0.530). Interestingly, the absolute number of EBV lytic epitope, RAKFKQLL-specific CD8(+) T cells increased over HIV seroconversion (4.78 to 9.54/ micro l; p = 0.011). Furthermore, the fraction of CD27-negative effector, RAK-specific CD8(+) T cells tended to increase (from 12.2 to 17.31% CD27(-); p = 0.051), in accordance with Ag-driven differentiation. In conclusion, both virological and immunological data support the idea that a new EBV viral setpoint is reached early in HIV infection, probably by EBV reactivation, as suggested by the preferential increase in EBV lytic epitope-specific CD8(+) T cells. These data may thus help to explain the lack of predictive value of EBV load for the occurrence of AIDS-related lymphoma.

Strong impact of highly active antiretroviral therapy on survival in patients with human immunodeficiency virus-associated Hodgkin's disease

Hodgkin's disease (HD) is the most common non-acquired immunodeficiency syndrome (AIDS)-defining malignancy in human immunodeficiency virus (HIV)-infected patients. We analysed the outcome of patients with HIV-associated HD (HIV-HD) with respect to the use and efficacy of highly active antiretroviral therapy (HAART) and other prognostic factors. To evaluate the effects of several variables on overall survival (OS), Kaplan-Meier statistics and extended Cox regression analysis were performed. Response to HAART was used as a time-dependent variable and was defined as an increase of >0.1 x 10(9) CD4 cells/l and/or at least one viral load <500 copies/ml during the first 2 years following diagnosis of HIV-HD. Fifty-seven patients with HIV-HD diagnosed between 1990 and 2002 were included in the study. In the Cox model, the only factors independently associated with OS were HAART response [relative hazard (RH) 0.19; 95% confidence interval (CI) 0.06-0.60], complete remission (RH 0.30, 95% CI 0.13-0.72), and age <or=45 years (RH 0.23; 95% CI 0.09-0.60). Median survival time in patients without HAART response was 18.6 months, whereas the median survival time in patients with HAART response was not reached (89% OS at 24 months). In this cohort, a significant improvement in survival was found in patients with HIV-HD who responded to HAART.

Short- and long-term effects of highly active antiretroviral therapy on Kaposi sarcoma-associated herpesvirus immune responses and viraemia

OBJECTIVE

To investigate the effect of highly active antiretroviral therapy (HAART) on Kaposi sarcoma-associated herpesvirus (KSHV) DNA load, anti-KSHV antibody responses and KSHV-specific CD8 T cell responses in HIV-infected individuals over a 2 year period.

DESIGN

Prospective study of 27 HIV-infected antiretroviral therapy-naive individuals, with (n = 4) and without KS (n = 23), before HAART and at 3-month intervals, during treatment with HAART.

METHODS

Sequential blood samples were collected for anti-KSHV antibody detection, KSHV DNA load in peripheral blood mononuclear cells (PBMC) and plasma, HIV Gag-specific and KSHV-specific CD8 T cell responses, HIV-1 plasma RNA load and CD4 and CD8 T cell counts.

RESULTS

KSHV DNA in PBMC and plasma became less detectable over time during HAART, in particular after 12 months. KSHV DNA was undetectable in plasma after 24 months on HAART. Anti-KSHV lytic, but not latent, antibody levels increased within 12 months of treatment. KSHV-specific CD8 T cell responses were absent prior to HAART but became detectable in some patients within 6 months of starting treatment, and continued to increase thereafter.

CONCLUSIONS

HAART (both protease inhibitor-based and non-nucleoside reverse transcriptase inhibitor-based antiretroviral combinations) is associated with immune reconstitution to KSHV and with undetectable KSHV viraemia. However, this restoration is apparent (in particular) only after a relatively long (> 24 months) period of treatment. These immune responses could contribute to the decreased incidence of KS during HAART, but it is unlikely to be a complete explanation for the often rapid resolution of KS when HAART is started.

Defective Control of Latent Epstein-Barr Virus Infection in Systemic Lupus Erythematosus

EBV infection is more common in patients with systemic lupus erythematosus (SLE) than in control subjects, suggesting that this virus plays an etiologic role in disease and/or that patients with lupus have impaired EBV-specific immune responses. In the current report we assessed immune responsiveness to EBV in patients with SLE and healthy controls, determining virus-specific T cell responses and EBV viral loads using whole blood recall assays, HLA-A2 tetramers, and real-time quantitative PCR. Patients with SLE had an approximately 40-fold increase in EBV viral loads compared with controls, a finding not explained by disease activity or immunosuppressive medications. The frequency of EBV-specific CD69+ CD4+ T cells producing IFN-gamma was higher in patients with SLE than in controls. By contrast, the frequency of EBV-specific CD69+ CD8+ T cells producing IFN-gamma in patients with SLE appeared lower than that in healthy controls, although this difference was not statistically significant. These findings suggest a role for CD4+ T cells in controlling, and a possible defect in CD8+ T cells in regulating, increased viral loads in lupus. These ideas were supported by correlations between viral loads and EBV-specific T cell responses in lupus patients. EBV viral loads were inversely correlated with the frequency of EBV-specific CD69+ CD4+ T cells producing IFN-gamma and were positively correlated with the frequencies of CD69+ CD8+ T cells producing IFN-gamma and with EBV-specific, HLA-A2 tetramer-positive CD8+ T cells. These results demonstrate that patients with SLE have defective control of latent EBV infection that probably stems from altered T cell responses against EBV.

Phenotype and Functional Characteristics of HIV-Specific Cytotoxic CD8+ T Cells in Chronically Infected Patients

BACKGROUND

Cytotoxic CD8+ T cells (CTLs) are critical for the control of viral infections. Although these cells can be recognized in most HIV-infected individuals, they fail to successfully control HIV replication. Distinct functional defects seem to limit their efficacy in HIV infection, although they have been not fully elucidated.

PATIENTS AND METHODS

Blood lymphocytes collected from 61 HLA-A0201+, untreated, chronically HIV-infected individuals were examined for the presence of CTLs against epitopes from HIV Gag and Pol proteins, using tetrameric complexes. Several functional aspects of these cells were further analyzed (immunophenotype; ability to produce interferon-gamma (IFN-gamma) in response to the specific peptide; proliferative capacity; and cytolytic activity). Lymphoproliferative responses of these cells confronting different stimulus were also evaluated. A longitudinal analysis was carried out in a subgroup who underwent antiretroviral therapy and were followed for 6 months.

RESULTS

CD8+ T cells staining with the tetramer complexes (Tet+) were detected in 44% of patients, with TetGag+ cells being more frequently detected and at higher levels than TetPol+ cells. Most Tet+ cells expressed a memory phenotype, showed an impaired ability to produce IFN-gamma when stimulated with the cognate peptide, and showed a very low expansion when cultured in the presence of the peptide. There was a negative correlation between the proportion of Tet+ cells producing IFN-gamma and plasma HIV-RNA. Although Tet+ cells diminished in most individuals after beginning antiretroviral therapy, some patients showed de novo appearance of Tet+ cells.

CONCLUSIONS

Most Tet+ cells in chronic HIV-infected individuals express a memory phenotype and show an impaired production of IFN-gamma and a lower proliferative response to specific HIV antigens. Interestingly, some individuals under successful antiretroviral therapy may show de novo appearance of specific CTLs. The implications of these findings are relevant for a better understanding of virus-host interactions.

Immune reconstitution in HIV infection and its relationship to cancer

HIV infection results in formidable immune dysfunction, widely affecting the immune system, but typified by T lymphopenia. This dysfunction includes a perturbed immune response to several persistent viruses that have a propensity to cause tumors. Effective control of HIV replication by highly active antiretroviral therapy (HAART) results in regeneration of the damaged immune system, and recent advances have allowed this immune reconstitution to be better defined. This article describes the immunodeficiency caused by HIV and the response of the immune system to HAART, with specific reference to the immune response to cancers associated with HIV infection.

Possible close analogy between HIV and EBV infection and, respectively, induced lymphomas

Within a system that operatively allows a progressive infection of T-lymphocytes by human immunodeficiency virus (HIV) in a manner that also entails depletion of the T-helper subset with directly resulting severe immunodeficiency, there might also be implicated a form of modulation of effects conducive to neoplastic transformation based on peculiar consequences of lesions induced by HIV integration within the cell genome. It might, in addition, be valid to consider Epstein Barr virus (EBV) as a cause of both B-lymphocyte infection and also of the creation of a whole population of atypical T-lymphocytes as seen in infectious mononucleosis, to constitute a close parallel analogy to HIV; in this manner it might be suggestive also of a series of analogous reactive lymphocytic changes also in AIDS; such a phenomenon might perhaps help account for the emergence in some AIDS patients of a primary Central Nervous System Lymphoma that is virtually always of B-cell derivation, analogous to Burkitt's lymphoma that is also of B-cell origin. In addition, the occurrence of T-cell rich B-cell lymphoma would appear perhaps to constitute a series of phenomena that intricately implicate both B-lymphocyte and T-lymphocyte participation in the genesis even of lymphomatous states as a category.

The differential ability of HLA B*5701+ long-term nonprogressors and progressors to restrict human immunodeficiency virus replication is not caused by loss of recognition of autologous viral gag sequences

Although the HLA B(*)5701 class I allele is highly overrepresented among human immunodeficiency virus (HIV)-infected long-term nonprogressors (LTNPs), it is also present at the expected frequency (11%) in patients with progressive HIV infection. Whether B57(+) progressors lack restriction of viral replication because of escape from recognition of highly immunodominant B57-restricted gag epitopes by CD8(+) T cells remains unknown. In this report, we investigate the association between restriction of virus replication and recognition of autologous virus sequences in 27 B(*)57(+) patients (10 LTNPs and 17 progressors). Amplification and direct sequencing of single molecules of viral cDNA or proviral DNA revealed low frequencies of genetic variations in these regions of gag. Furthermore, CD8(+) T-cell recognition of autologous viral variants was preserved in most cases. In two patients, responses to autologous viral variants were not demonstrable at one epitope. By using a novel technique to isolate primary CD4(+) T cells expressing autologous viral gene products, it was found that 1 to 13% of CD8(+) T cells were able to respond to these cells by gamma interferon production. In conclusion, escape-conferring mutations occur infrequently within immunodominant B57-restricted gag epitopes and are not the primary mechanism of virus evasion from immune control in B(*)5701(+) HIV-infected patients. Qualitative features of the virus-specific CD8(+) T-cell response not measured by current assays remain the most likely determinants of the differential abilities of HLA B(*)5701(+) LTNPs and progressors to restrict virus replication.

Immunotherapy for Epstein-Barr virus-associated cancers in children

Latent Epstein-Barr virus (EBV) infection is associated with several malignancies, including Burkitt's lymphoma, Hodgkin's disease, nasopharyngeal carcinoma, and post-transplant lymphoproliferative disease (LPD). The presence of EBV antigens in these tumors provides a target for immunotherapy approaches, and immunotherapy with EBV-specific cytotoxic T cells (CTLs) has proved effective in post-transplant LPDs, which are highly immunogenic tumors expressing type III latency. The malignant cells in Hodgkin's disease and nasopharyngeal carcinoma express type II latency and hence a more restricted pattern of EBV antigens. Trials with autologous EBV-specific CTL responses are under way in both of these diseases, and while some activity has been seen, no patient has yet been cured. This reduced CTL efficacy may reflect either downregulation of immunodominant EBV proteins, which are major CTL targets, or the ability of these tumors to evade the immune response by secreting inhibitory cytokines. Further improvement of EBV-specific CTL therapy for these type II latency tumors will require improved methods to activate and expand CTLs specific for the subdominant EBV genes expressed and to genetically modify the expanded CTLs to render them resistant to inhibitory cytokines. If these strategies to improve the therapeutic potential of immunotherapy for EBV-associated tumors prove successful, this type of treatment may be adapted to other tumors expressing known (viral) antigens.

The functional CD8 T cell response to HIV becomes type-specific in progressive disease

High levels of HIV-specific CD8 T cells are demonstrable throughout HIV disease using laboratory assays that measure responses to consensus epitopes. In acute infection, the dynamics of the antiviral CD8 T cell response correlate well with the decline in viremia. However in chronic infection, although responses are detected against a broader spectrum of epitopes, virus-specific CD8 T cells are apparently unable to control viral replication. To investigate whether CD8 T cells responding to consensus epitopes may have lost their in vivo relevance in the chronic phase because of viral evolution driven by immune pressure, we compared the CD8 T cell response to CD4 T cell targets infected with either lab-adapted HIV(IIIB) or the patient's own virus. The magnitude of the IFN-gamma response declined with disease progression, especially to autologous virus. T cell receptor (TCR) clonotypes of HIV(IIIB) and autologous virus-responding cells were determined by sequencing TCR beta chain variable (TCRBV) genes. In two of three asymptomatic donors, the dominant clonotypes overlapped, whereas in five symptomatic patients, the TCR clonotypes responding to HIV(IIIB) virus were completely different from those responding to autologous virus. Moreover, in cytolytic assays, T cell lines derived from IFN-gamma(+) cells responding to lab-adapted or autologous virus cross-recognized target cells infected with either virus in asymptomatic subjects with shared TCR clonotypes but not in progressors with differing clonotypes. Therefore, in advanced-stage patients, viral-specific CD8 T cells recognizing consensus epitopes persist from an earlier response but no longer effectively recognize autologous virus.