Low-dose daily interleukin-2 immunotherapy: accelerating immune restoration and expanding HIV-specific T-cell immunity without toxicity

Low-dose interleukin-2 selectively corrects regulatory T cell defects in patients with systemic lupus erythematosus

OBJECTIVES

Defects in regulatory T cell (Treg) biology have been associated with human systemic autoimmune diseases, such as systemic lupus erythematosus (SLE). However, the origin of such Treg defects and their significance in the pathogenesis and treatment of SLE are still poorly understood.

METHODS

Peripheral blood mononuclear cells (PBMC) from 61 patients with SLE and 52 healthy donors and in vitro IL-2 stimulated PBMC were characterised by multicolour flow cytometry. Five patients with refractory SLE were treated daily with subcutaneous injections of 1.5 million IU of human IL-2 (aldesleukin) for five consecutive days, and PBMC were analysed by flow cytometry.

RESULTS

Patients with SLE develop a progressive homeostatic dysbalance between Treg and conventional CD4+ T cells in correlation with disease activity and in parallel display a substantial reduction of CD25 expression on Treg. These Treg defects resemble hallmarks of IL-2 deficiency and lead to a markedly reduced availability of functionally and metabolically active Treg. In vitro experiments revealed that lack of IL-2 production by CD4+ T cells accounts for the loss of CD25 expression in SLE Treg, which could be selectively reversed by stimulation with low doses of IL-2. Accordingly, treatment of patients with SLE with a low-dose IL-2 regimen selectively corrected Treg defects also in vivo and strongly expanded the Treg population.

CONCLUSIONS

Treg defects in patients with SLE are associated with IL-2 deficiency, and can be corrected with low doses of IL-2. The restoration of endogenous mechanisms of immune tolerance by low-dose IL-2 therapy, thus, proposes a selective biological treatment strategy, which directly addresses the pathophysiology in SLE.

Structured Treatment Interruptions and Low Doses of IL-2 in Patients with Primary HIV Infection. Inflammatory, Virological and Immunological Outcomes

BACKGROUND

Interventions during primary HIV infection (PHI) can modify the clinical course during the chronic phase. The long-term effect of structured treatment interruptions (STI) followed by low doses of interleukin-2 (IL-2) in treated PHI patients is unknown.

METHODS

Twelve PHI patients with viral load (VL) <20 copies/mL, CD4 cells >500 cells/mm3, and CD4/CD8 ratio >1, on antiretroviral therapy (ART) initiated within the first 90 days of infection and continued for at least 12 months were included. They underwent four STI and were then allocated (week 0 of the study) to ART alone or ART plus low doses of IL-2. ART was stopped once VL <20 copies/mL ('final stop'). Primary endpoints were VL<3000 copies/mL and CD4 cells >500 cells/mm3 at 48 weeks; secondary endpoints were immune activation, inflammatory markers until 48 weeks and the time before resuming ART (CD4 <350 cells/mm3 or AIDS) after 'final stop', compared between groups.

RESULTS

Ten out of 12 patients were males, median age was 35 years and the main risk was men-who-have-sex-with-men. Only one out of 12 patients (in the STI group) maintained VL<3000 copies/mL and CD4 cells >500 cells/mm3 without ART at 48 weeks. All other virological and immunological parameters were comparable between groups at week 0, 'final stop' and week 48. However, the proportion of CD8-CD38+ cells, tumor necrosis factor and srIL-2 were higher in the IL-2 group at 'final stop' and week 24. All these differences vanished during follow-up. At 5 years after the final stop 3 out of 6 patients in the IL-2 group and 6 out of 6 patients in the STI group have resumed ART (P = 0.19).

CONCLUSIONS

STI and IL-2 failed to achieve virological control after ART interruption. STI were not deleterious in long-term follow-up, an important issue for eradication and functional cure trials.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02300623.

Cytokine immunomodulation for the treatment of infectious diseases: lessons from primary immunodeficiencies

Traditionally, management of infectious diseases focuses on identification of the causative microbe and the use of pathogen-targeted therapy. With increasing antimicrobial resistance, novel approaches are required. One strategy is to modulate those natural host immune responses that critically mediate resistance to specific microbes. Clinically, this host-directed tactic could be used either alone or in combination with antimicrobial therapy. While conceptually attractive, there is potential concern that the pathways governing host resistance to pathogens in animal models may not extrapolate linearly to humans. Targeting these immune processes clinically may precipitate damaging, epiphenomenal responses. The field of Primary Immunodeficiencies focuses on the characterization of humans with inborn errors of immunity. These rare conditions permit the identification of those molecular and cellular processes that are central to human susceptibility to microbes. In efforts to compensate for defective host responses, this field has also provided a wealth of clinical experience in the effective use of cytokines to treat various active infections, while demonstrating their safety. In this review, we provide a historical perspective of the treatment of infectious diseases, evolving from a focus on the microbe, to an understanding of human immunity; we then outline the growing contribution of Primary Immunodeficiencies to the rational use of adjunctive cytokine immunotherapy in the management of infections.

Enhanced endogenous type I interferon cell-driven survival and inhibition of spontaneous apoptosis by Riluzole

Highly active antiretroviral therapy (HAART), although effective in improving the survival of HIV-1-infected individuals, has not been able to reconstitute the adaptive immune response. We have described the use of novel chemical agents to restore T-cell survival/proliferation by inducing cytokine production. Due to its cationic amphiphilic structure, these molecules appear to enhance immune restoration. In this study, we investigated the action of Riluzole (2-amino-6-trifuromethoxybenzothiazole) in HIV-1 infection. Riluzole is able to increase (effective dose from 1 to 1000 nM) the cell-survival of T cells from HIV-1-infected patients and inhibit spontaneous apoptosis. The immunomodulatory effect of riluzole-sensitized cells was ascribed to endogenous type I interferon (IFN) derived from monocytes. Riluzole might be used for restoring the cell survival of immunocompromised patients and eliminating latent infected cells upon HIV-1 reactivation.

Nitric oxide production in mouse and rat macrophages: A rapid and efficient assay for screening of drugs immunostimulatory effects in human cells

Activation of inducible nitric oxide (NO) synthase (iNOS) and resulting high-output NO release is known to depend on the action of cytokines. We investigated in vitro production of NO by resident peritoneal macrophages from mice and rats, and secretion of cytokines by these cells as well as by human peripheral blood mononuclear cells (PBMC). The cells were cultured in the presence of a selected group of acyclic nucleoside phosphonates that have previously been shown to possess immunobiological potential. Several of the compounds enhanced production of NO in animal macrophages. This activity was associated with stimulatory effects on secretion of cytokines such as TNF-alpha in all mouse and rat macrophages and human PBMC, and IL-10 in mouse and human cells. Statistically highly significant correlation between the range of NO biosynthesis in rodent cells and extent of cytokine stimulation in human PBMC has been observed. It is suggested that the NO assay may be regarded as an efficient, economical and relatively reliable tool in primary screening for intrinsic immunostimulatory activity of compounds in human cell system, at least from the point of view of cytokine secretion.

Genome wide expression profiling of human peripheral blood mononuclear cells stimulated with BAY 50-4798, a novel T cell selective interleukin-2 analog

BAY 50-4798, a novel, engineered form of interleukin (IL)-2, is a selective agonist for the high-affinity IL-2 receptor and induces the proliferation of activated human T cells with potency similar to recombinant IL-2 (rIL-2), but has reduced proliferative activity on natural killer cells and is associated with a diminished secondary cytokine cascade. In the current study, the transcriptional profiles of human peripheral blood mononuclear cells (PBMCs) stimulated in vitro with BAY 50-4798 and rIL-2 were compared using Affymetrix microarray technology in combination with Ingenuity Pathway Analysis (IPA) to determine whether there are quantitative or qualitative differences in the molecular networks activated by these IL-2 analogs. A total of 299 genes were differentially expressed in response to the two IL-2 analogs, with an increase in the number of differences over time. Consistent with the fact that BAY 50-4798 interacts with fewer forms of the IL-2 receptor than rIL-2 to activate fewer cell types, 169 genes were expressed at lower levels in PBMCs cultured with BAY 50-4798 compared with IL-2. These genes were mainly categorized as cytokines and chemokines, and were used to build multiple molecular interaction networks, the most significant of which centered around a subunit of NF-kappaB, which is known to play a pivotal role in inflammation, and was associated with cell death. Of the genes induced in response to BAY 50-4798, only 25% were expressed at lower levels than those induced by rIL-2. Moreover, despite its more selective receptor targeting compared with rIL-2, BAY 50-4798 caused higher levels of expression of 130 genes, which predominantly fell into categories associated with metabolism and transcription. We interpret these results as consistent with the expected transcriptional profile of a mutein engineered and demonstrated to have diminished inflammatory effects yet fully retain selected features of IL-2 activity. In addition to demonstrating that the responses to BAY 50-4798 are characterized by differential expression of genes known to be induced by IL-2, we report for the first time the induction of a significant number of genes not previously reported in the context of IL-2 biology.

The lytic NK cell immunological synapse and sequential steps in its formation

Natural killer (NK) cells are lymphocytes of the innate immune system that are critical in host defense. They are best known for their ability to mediate cytotoxicity, which involves a coordinated series of events resulting in the directed secretion of lytic granules onto a target cell. This process requires the formation of an immunological synapse in NK cells. The NK cell immunological synapse involves the reorganization of the actin cytoskeleton and clustering of certain cell surface receptors in the NK cell at the interface with the target cell. The lytic NK cell immunological synapse, specialized for mediating cytotoxicity, is further distinguished by the polarization of lytic granules, which are then secreted through this region onto the target cell. These events unfold in a definitive sequence and lead to critical checkpoints that provide regulatory control at specific stages in the formation of the NK cell lytic synapse.

Optimization of in vitro expansion of macaque CD4 T cells using anti-CD3 and co-stimulation for autotransfusion therapy

BACKGROUND

Our laboratory has previously shown that adoptive transfer of in vitro-expanded autologous purified polyclonal CD4(+) T cells using anti-CD3/CD28-coated beads induced antiviral responses capable of controlling SIV replication in vivo.

METHODS

As CD4(+) T cells comprise several phenotypic and functional lineages, studies were carried out to optimize the in vitro culture conditions for maximal CD4(+) T-cell expansion, survival and delineate the phenotype of these expanded CD4(+) T cells to be linked to maximal clinical benefit.

RESULTS AND CONCLUSIONS

The results showed that whereas anti-monkey CD3gamma/epsilon was able to induce T-cell proliferation and expansion in combination with antibodies against multiple co-stimulatory molecules, monkey CD3epsilon cross reacting antibodies failed to induce proliferation of macaque CD4(+) T cells. Among co-stimulatory signals, anti-CD28 stimulation was consistently superior to anti-4-1BB, CD27 or ICOS while the use of anti-CD154 failed to deliver a detectable proliferation signal. Increasing the relative anti-CD28 co-stimulatory signal relative to anti-CD3 provided a modest enhancement of expansion. Additional strategies for optimization included attempts to neutralize free radicals, enhancement of glucose uptake by T cells or addition of T-cell stimulatory cytokines. However, none of these strategies provided any detectable proliferative advantage. Addition of 10 autologous irradiated feeder cells/expanding T cell provided some enhancement of expansion; however, given the high numbers of T cell needed, this approach was deemed impractical and costly, and lower ratios of feeder to expanding T cells failed to provide such benefit. The most critical parameter for efficient expansion of purified CD4(+) T cells from multiple monkeys was the optimization of space and culture conditions at culture inception. Finally, anti-CD3/28-expanded CD4(+) T cells uniformly exhibited a central memory phenotype, absence of CCR5 expression, marked CXCR4 expression in vitro, low levels of caspase 3 but also of Bcl-2 expression.

Reduced Secondary Cytokine Induction by BAY 50-4798, a High-Affinity Receptor-Specific Interleukin-2 Analog

Recombinant interleukin-2 (IL-2) (aldesleukin, Proleukin, Chiron, Emeryville, CA) is approved for treatment of cancer patients and under investigation in HIV-infected individuals. However, treatment with aldesleukin is associated with toxicity, which may be due to its elicitation of inflammatory mediators from cells that express the intermediate-affinity IL-2 receptor. BAY 50-4798, a novel IL-2 analog, is a selective agonist for the high-affinity receptor. It induces the proliferation of activated T cells with a potency similar to that of aldesleukin but has reduced activity on cells expressing the intermediate-affinity receptor. In the current study, we compared cytokine responses elicited in peripheral blood mononuclear cell (PBMC) cultures stimulated with BAY 50-4798 or aldesleukin. BAY 50-4798 induced approximately 5-fold lower mean levels of endogenous IL-2 than aldesleukin, and at least 50% lower levels of proinflammatory cytokines, such as tumor necrosis fctor-alpha (TNF-alpha), IL-1beta, IL-6, and interferon-gamma (IFN-gamma). Furthermore, statistically significant reductions in the levels of IL-5, IL-8, IL-10, IL-13, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were observed in response to BAY 50-4798. These findings increase our understanding of the biologic action of BAY 50-4798 and suggest a mechanism by which it may exhibit better safety than aldesleukin in humans.

Daily low-dose subcutaneous interleukin-2 added to single- or dual-nucleoside therapy in HIV infection does not protect against CD4+ T-cell decline or improve other indices of immune function: results of a randomized controlled clinical trial (ACTG 248)

CONTEXT

Approaches to preserve or enhance immune function in HIV-1 infection are needed.

OBJECTIVES

To examine the ability of daily low-dose interleukin-2 (IL-2) in combination with antiretroviral therapy to preserve circulating CD4+ T-cell counts, the clinical safety and tolerability of this treatment, and safety with respect to changes in plasma HIV-1 RNA levels.

DESIGN

Twenty-four-week, phase 2, multicenter, randomized, open-label trial conducted at 12 AIDS Clinical Trials Units between September 1995 and May 1997.

PARTICIPANTS

A total of 115 HIV-infected persons with screening CD4+ T-cell counts between 300 and 700 cells/mm who were on stable single- or dual-nucleoside therapy for at least 2 months, 11% of whom were also on a protease inhibitor at study entry.

INTERVENTIONS

Patients were randomly assigned to receive IL-2 at a dose of 1 million IU subcutaneously once daily plus continued anti-retroviral therapy (ART + IL-2, n = 57) vs. continued ART alone (ART alone, n = 58). IL-2 dose reductions were made for objective or subjective toxicities. All subjects randomly assigned to the IL-2 arm who interrupted ART were also required to discontinue IL-2 for the same period.

MAIN OUTCOME MEASURES

The primary endpoint was a decrease in CD4 T-cell count from baseline; the safety analysis was based on change in plasma HIV RNA by bDNA; and clinical safety and tolerability were analyzed by standard clinical criteria.

RESULTS

Of the patients with a baseline CD4 T-cell count recorded, 15 (27%) of 55 patients randomly assigned to ART alone had a drop of > or =25% in their CD4 T-cell count and 23 (41%) of 56 patients randomly assigned to ART + IL-2 had a drop of > or =25% in their CD4 T-cell count at some time over the 24 weeks of the study. This difference was not statistically significant. There was a statistically significant greater variance in CD4 T-cell counts in the IL-2-treated group. More patients in the IL-2 group had at least a 25% increase in CD4 T-cell counts over baseline (34 vs. 13%, P = 0.007). A comparison of grade 3 or worse toxicity showed no differences between the arms, but IL-2 was associated with significantly more grade 2 or worse general body symptoms, primarily discomfort and fatigue. There was no significant difference between the groups with regard to changes in plasma HIV RNA, lymphocyte proliferation, natural killer cell activity, skin test responses to recall antigens, or antibody responses to immunization. Plasma markers of immune activation all increased significantly in IL-2 recipients.

CONCLUSIONS

In patients with baseline CD4 T-cell counts > or =300 cells/mm primarily treated with single- or dual-nucleoside ART, subcutaneously administered IL-2 at a dose of 1 million IU daily for up to 24 weeks had low toxicity but showed no consistent benefit in preventing decline in CD4 T-cell counts and minimal evidence of immunologic improvement vs. continued ART alone.

Effects of triterpene saponins from Astragalus species on in vitro cytokine release

Roots of Astragalus species are used to treat leukemia and for wound healing in Turkish folk medicine. In order to evaluate this information, the effect of 13 cycloartane- and 1 oleanan-type triterpene saponins isolated from Turkish species (Astragalus brachypterus, Astragalus cephalotes, Astragalus microcephalus, and Astragalus trojanus), as well as methanol extracts from the roots of three Astragalus species (Astragalus cephalotes, Astragalus oleifolius and Astragalus trojanus) were studied. Cytokine concentrations of interleukins IL-1beta, IL-8 and TNF-alpha after bacterial lipopolysaccharide (LPS) and IL-2, IL-4 and INF-gamma after phorbolacetate (PHA) stimulation were determined using commercial enzyme-linked immunosorbent assay (ELISA) kits. All triterpene saponins tested in the present study showed a prominent IL-2 inducing activity between 35.9% and 139.6%. Among the extracts the highest score was obtained for Astragalus oleifolius (141.2%). Glycosides of 20,24-epoxy and 20,25-epoxy cycloartanes showed higher IL-2 inducing activity than those of acyclic-cycloartane derivatives as well as aglycone of 20,24-epoxy cycloartanes, cycloastrogenol. Especially the activity of Astragaloside VII, a tridesmosidic glycoside of cycloastrogenol, was the most remarkable. The oleanan-type triterpene saponin also showed a prominent IL-2 inducing activity. IL-2 is a cytokine produced by activated T cells, which has shown powerful immunostimulatory and antineoplastic properties. Accordingly, the IL-2 inducing activity of the triterpene saponins might be the mechanism involved in order to explain the immunomodulatory and anticancer effects of Astragalus species.

The Use of Interleukin-2 in Human Immunodeficiency Virus Infection

Advances in antiretroviral therapy for human immunodeficiency virus (HIV) have led to reductions in HIV-related morbidity and mortality. Although antiretroviral therapy has shown success in suppressing viral loads, it does not adequately restore the immune system in all individuals infected with HIV. In light of this incomplete success, interleukin (IL)-2 is being evaluated as adjunctive therapy to antiretroviral therapy. The agent has demonstrated mixed yet promising results in restoring immune function in patients who are HIV positive.

Use of recombinant cytokines for optimized induction of antiviral immunity against SIV in the nonhuman primate model of human AIDS

Outbreaks of infectious diseases such as HIV and the much televised and attention-getting outbreaks of diseases such as Ebola, Hantaviruses, and the most recent outbreak of SARS have induced a significant new interest in the formulations and more importantly the science of vaccinology, which has previously to a large extent been conducted empirically. Our laboratory has focused on the use of recombinant nonhuman primate cytokines as adjunctive therapies for inducing antigen-specific immune responses in monkeys because most recombinant human cytokines appear to be immunogenic. This article provides a summary of our work with such cytokines, which includes attempts to define optimum dosing schedules that lead to optimal primary and lasting memory antigen-specific immune responses.

IL-15 is superior to IL-2 in the generation of long-lived antigen specific memory CD4 and CD8 T cells in rhesus macaques

Using tetanus toxoid (TT) and influenza (Flu) immunization of rhesus macaques as a model, the effect of IL-2 and IL-15 on the generation and maintenance of antigen specific memory T cells was evaluated following primary and secondary immunization. Daily cytokine administration expanded primarily effector but not memory cells, while spacing cytokine administration to q3-7 days markedly enhanced TT and Flu specific memory responses. Following primary immunization, TT specific CD4 and influenza matrix protein (Flu-MP) specific CD8 effector responses were enhanced by IL-2 administration but CD8 specific memory responses were no different from cytokine non-treated monkeys. In contrast, expansion of Flu specific CD8 cells with IL-15 was only modest but resulted in significantly elevated levels of memory cells at 6 months. IL-15 also significantly enhanced early and late TT specific CD4 responses. The highest levels of primary effector and memory T cells were observed following alternate administration of both IL-2 and IL-15. Following booster immunization, however, only IL-15 appeared able to enhance CD8 T cell responses while IL-2 or IL2/IL-15 administration were less effective.

Management of adverse effects associated with the use of interleukin-2 in patients with HIV infection

Therapy with interleukin-2 challenges both the patient and the clinic staff. Pre-education and side effect management are crucial to the successful administration of each cycle of interleukin-2.

Immune Mechanisms in HIV Infection

Recent advances in immunobiology have led to a greater understanding of the healthy immune system and the complex pathogenesis of human immunodeficiency virus (HIV) infection. Knowledge of the mechanisms underlying the decrease in CD4+ T cells is rapidly evolving as a result of new assays, genetic advances, and recombinant DNA technologies. Studying the immune responses of long-term non-progressors is also providing insight into the immunopathology of HIV. Trials using highly active antiretroviral therapy and immune modulators have shown that it may be possible to reverse damage to the immune system and increase CD4+ T-cell numbers. Current and future findings might provide the knowledge necessary to identify effective HIV drugs and vaccines with acceptable toxicity profiles and to determine whether it will be possible to fully restore immune system function in patients with HIV disease.

Diminished proliferation of human immunodeficiency virus-specific CD4+ T cells is associated with diminished interleukin-2 (IL-2) production and is recovered by exogenous IL-2

Virus-specific CD4(+) T-cell function is thought to play a central role in induction and maintenance of effective CD8(+) T-cell responses in experimental animals or humans. However, the reasons that diminished proliferation of human immunodeficiency virus (HIV)-specific CD4(+) T cells is observed in the majority of infected patients and the role of these diminished responses in the loss of control of replication during the chronic phase of HIV infection remain incompletely understood. In a cohort of 15 patients that were selected for particularly strong HIV-specific CD4(+) T-cell responses, the effects of viremia on these responses were explored. Restriction of HIV replication was not observed during one to eight interruptions of antiretroviral therapy in the majority of patients (12 of 15). In each case, proliferative responses to HIV antigens were rapidly inhibited during viremia. The frequencies of cells that produce IFN-gamma in response to Gag, Pol, and Nef peptide pools were maintained during an interruption of therapy. In a subset of patients with elevated frequencies of interleukin-2 (IL-2)-producing cells, IL-2 production in response to HIV antigens was diminished during viremia. Addition of exogenous IL-2 was sufficient to rescue in vitro proliferation of DR0101 class II Gag or Pol tetramer(+) or total-Gag-specific CD4(+) T cells. These observations suggest that, during viremia, diminished in vitro proliferation of HIV-specific CD4(+) T cells is likely related to diminished IL-2 production. These results also suggest that relatively high frequencies of HIV-specific CD4(+) T cells persist in the peripheral blood during viremia, are not replicatively senescent, and proliferate when IL-2 is provided exogenously.

Combinatorial immunotherapies for infectious diseases

Combating pathogenic organisms by combinatorial approaches involving appropriate immune response molecules and antimicrobial drugs represents a progessively more apparent and successful therapeutic paradigm for the treatment of acute and chronic persistent infectious diseases. This review explores areas of current innovation and provides an update of the present state of knowledge concerning combination of chemotherapy with several immune-based interventions in infections. In the future, a better understanding of microbial immune modulation and evasion may continue to open new avenues of inquiry and carefully targeted application of adjunctive immunotherapies.

Retrospective analysis of HHV-8 viremia and cellular viral load in HIV-seropositive patients receiving interleukin 2 in combination with antiretroviral therapy

The combination of interleukin 2 (IL-2) and antiretroviral therapy (ART) represents an emerging strategy in the treatment of patients infected with HIV. Aside from its immunomodulatory role, however, IL-2 may induce replication of human herpesvirus 8 (HHV-8)/Kaposi sarcoma (KS)–associated herpesvirus. We retrospectively evaluated HHV-8 plasma viremia and cellular load, as well as anti–HHV-8 antibody titers, in sequential samples from 84 patients receiving ART alone or in combination with IL-2. At baseline, HHV-8 plasma viremia was present only in 2 HHV-8–seropositive patients in whom KS subsequently developed during or immediately after termination of IL-2 therapy. The level of viremia increased during follow-up and peaked at the time of the clinical manifestation of KS. Moreover, transient peaks of HHV-8 viremia were temporally associated with administration of IL-2. HHV-8 plasma viremia was never detected in the other 47 patients receiving IL-2 nor in 35 controls treated only with ART. Thus, IL-2 therapy seems safe in most patients infected with both HIV and HHV-8, except for those with detectable HHV-8 viremia, who may not be eligible for IL-2 treatment.

Immune reconstitution

Immune reconstitution in HIV-infected patients remains a potential mechanism to explain delayed disease progression and increased survival following suppressive therapy. Many discrepancies remain to be studied. Is an immune response to HIV protective? Why are anti-HIV CD4 responses lost so quickly in progressors and how can they be restored? What is the damage to the immune system that occurs early in disease and why can it not be overcome by simply controlling viral replication? Will management of immune reconstitution be used in future adjunct treatment strategies (vaccine or STI)? Because HAART is not the answer to long-term management of HIV throughout the world, the recovery of immune function and it's potential to control viral replication remains a key goal in the long-term management of HIV-infected persons.

Immune therapy: non-highly active antiretroviral therapy management of human immunodeficiency virus-infected patients

The complexity of human immunodeficiency virus (HIV) immunopathogenesis has prompted multiple strategic approaches to re-establish normal immune responses. Highly active antiretroviral therapy (HAART) can control viral replication, but it is unable to restore HIV-specific immunity. Newer approaches for managing HIV infection are focusing on cell-mediated immune responses, including the potential for improved immunologic control over HIV replication. Cytokines, such as interleukin (IL)-2 and IL-12, are being evaluated for their ability to enhance cell-mediated immunity, which is thought to be critical for immunologic control. Initial studies with IL-2 have demonstrated an improvement in CD4 cell counts, and large randomized trials are underway to determine the long-term clinical efficacy of IL-2 in combination with antiretroviral therapy, including HAART. Stimulating the immune response against HIV by use of exogenous (therapeutic vaccination) or endogenous (structured treatment interruption) antigens with or without immune adjuvants or cytokines, such as IL-2, is another approach currently being explored.