Cytokines, plasma immune activation markers, and clinically relevant surrogate markers in human immunodeficiency virus infection

Prevalence of Cytopenia and its Correlation with Immunosuppression in Naïve HIV-1 Infected Patients Initiating First-Line Antiretroviral Therapy: A Pilot Study

BACKGROUND

Cytopenias serve as common indicators and crucial predictive tools for evaluating disease progression and therapeutic outcomes in individuals with human immunodeficiency virus (HIV) infection. This study aimed to assess the prevalence of cytopenias and their correlation with the level of immunosuppression in treatment-naive HIV-infected participants after initiating highly active combined antiretroviral drug therapy (cART24).

MATERIALS AND METHODS

This prospective study focused on evaluating cytopenia in 44 treatment-naive HIV-infected patients who consented to initiate cART and were consecutively enrolled. The research was conducted at the Nasara HIV Treatment & Care Centre of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, Nigeria, spanning from December 2016 to January 2018. Cytopenias, including anemia, leucopenia, lymphocytopenia, and thrombocytopenia, were defined and assessed according to World Health Organization guidelines. A combination of cross-sectional and longitudinal mixed-design two-step analysis was employed to validate our findings.

RESULTS

The median time from enrollment to cART initiation was 7 days, following the universal test and treat protocol. The prevalence of cytopenia was 75% at the baseline before treatment and increased to 84% after cART24 administration. There were no statistically significant differences in the median values of immuno-hematological parameters between baseline and after cART24 initiation (P >0.05). In terms of longitudinal assessment, the prevalence of anemia, leucopenia, lymphopenia, and thrombocytopenia at baseline were 66%, 23%, 0%, and 11%, respectively, and after cART24, the rates were 66%, 29%, 5%, and 20%. Notably, the prevalence of cytopenia correlated with declining CD4+ T cell counts. Among instances of unicytopenia, 58% exhibited isolated anemia, 6% had lone leucopenia, and 6% had solitary thrombocytopenia. Additionally, 27% demonstrated bi-cytopenia, and 3% exhibited pancytopenia. Interestingly, none of the study participants presented with lymphopenia. The most common combination was anemia and thrombocytopenia. Both longitudinal and cross-sectional analytical findings were consistent.

CONCLUSION

In treatment-naive HIV-infected individuals, the prevalence of cytopenias, particularly anemia and thrombocytopenia, was substantial and correlated with the degree of immunosuppression as indicated by CD4+ T cell counts. These cytopenias persisted despite initiation of cART24, highlighting the complexity of hematological manifestations in HIV infection. Our study underscores the significant hematopathological impact of HIV and antiretroviral therapy, highlighting the necessity for preventive strategies to mitigate these adverse effects.

A high-throughput screening RT-qPCR assay for quantifying surrogate markers of immunity from PBMCs

Immunoassays that quantitate cytokines and other surrogate markers of immunity from peripheral blood mononuclear cells (PBMCs), such as flow cytometry or Enzyme-Linked Immunosorbent Spot (ELIspot), allow highly sensitive measurements of immune effector function. However, those assays consume relatively high numbers of cells and expensive reagents, precluding comprehensive analyses and high-throughput screening (HTS). To address this issue, we developed a sensitive and specific reverse transcription-quantitative PCR (RT-qPCR)-based HTS assay, specifically designed to quantify surrogate markers of immunity from very low numbers of PBMCs. We systematically evaluated the volumes and concentrations of critical reagents within the RT-qPCR protocol, miniaturizing the assay and ultimately reducing the cost by almost 90% compared to current standard practice. We assessed the suitability of this cost-optimized RT-qPCR protocol as an HTS tool and determined the assay exceeds HTS uniformity and signal variance testing standards. Furthermore, we demonstrate this technique can effectively delineate a hierarchy of responses from as little as 50,000 PBMCs stimulated with CD4⁺ or CD8⁺ T cell peptide epitopes. Finally, we establish that this HTS-optimized protocol has single-cell analytical sensitivity and a diagnostic sensitivity equivalent to detecting 1:10,000 responding cells (i.e., 100 Spot Forming Cells/10⁶ PBMCs by ELIspot) with over 90% accuracy. We anticipate this assay will have widespread applicability in preclinical and clinical studies, especially when samples are limited, and cost is an important consideration.

Impact of Plasma IP-10/CXCL10 and RANTES/CCL5 Levels on Neurocognitive Function in HIV Treatment-Naive Patients

Immune activation, which is accompanied by the production of proinflammatory cytokines, is a strong predictor of disease progression in HIV infection. Inflammation is critical in neuronal damage linked to HIV-associated neurocognitive disorders. We examined the relationship between plasma cytokine levels and deficits in neurocognitive function. Multiplex profiling by Luminex^® technology was used to quantify 27 cytokines/chemokines from 139 plasma samples of people living with HIV (PLWH). The relationship of plasma cytokine markers, clinical parameters, and cognitive impairment, was assessed using Spearman correlations. Partial least squares regression and variable importance in projection scores were used for further evaluation of the association. Forty-nine (35.3%) participants exhibited neurocognitive impairment based on a global deficit score (GDS) of at least 0.5 and 90 (64.7%) were classified as nonimpaired. Twenty-three (16.5%) initiated on combination antiretroviral therapy for 4 weeks before cognitive assessment and 116 (83.5%) were not on treatment. We identified five proinflammatory cytokines that were significant predictors of GDS namely, IP-10 (β = 0.058; p = .007), RANTES (β = 0.049; p = .005), IL-2 (β = 0.047, p = .006), Eotaxin (β = 0.042, p = .003), and IL-7 (β = 0.039, p = .003). IP-10 and RANTES were the strongest predictors of GDS. Both cytokines correlated with plasma viral load and lymphocyte proviral load and were inversely correlated with CD4⁺ T cell counts. IP-10 and RANTES formed a separate cluster with highest proximity. Study findings describe novel associations among IP-10, RANTES, cognitive status, plasma viral load, and cell-associated viral load.

Evaluation of the Immunoprotective Potential of Recombinant Paraflagellar Rod Proteins of Trypanosoma evansi in Mice

Trypanosomosis, caused by Trypanosoma evansi, is an economically significant disease of livestock. Systematic antigenic variation by the parasite has undermined prospects for the development of a protective vaccine that targets the immunodominant surface antigens, encouraging exploration of alternatives. The paraflagellar rod (PFR), constituent proteins of the flagellum, are prominent non-variable vaccine candidates for T. evansi owing to their strategic location. Two major PFR constituent proteins, PFR1 (1770bp) and PFR2 (1800bp), were expressed using Escherichia coli. Swiss albino mice were immunized with the purified recombinant TePFR1 (89KDa) and TePFR2 (88KDa) proteins, as well as with the mix of the combined proteins at equimolar concentrations, and subsequently challenged with virulent T. evansi. The PFR-specific humoral response was assessed by ELISA. Cytometric bead-based assay was used to measure the cytokine response and flow cytometry for quantification of the cytokines. The recombinant TePFR proteins induced specific humoral responses in mice, including IgG1 followed by IgG2a and IgG2b. A balanced cytokine response induced by rTePFR 1 and 2 protein vaccination associated with extended survival and improved control of parasitemia following lethal challenge. The observation confirms the immunoprophylactic potential of the covert antigens of T. evansi.

Inflammation and Risk of Depression in HIV: Prospective Findings From the Multicenter AIDS Cohort Study

Studies suggest that inflammation might be involved in the pathogenesis of depression. Individuals with human immunodeficiency virus (HIV) have a higher risk of depression and elevated inflammatory profiles. Despite this, research on the link between inflammation and depression among this high-risk population is limited. We examined a sample of men who have sex with men from the Multicenter AIDS Cohort Study in prospective analyses of the association between inflammation and clinically relevant depression symptoms, defined as scores >20 on Center for Epidemiological Studies Depression Scale. We included 1,727 participants who contributed 9,287 person-visits from 1984 to 2010 (8,218 with HIV (HIV+) and 1,069 without (HIV-)). Exploratory factor analysis (EFA) was used to characterize underlying inflammatory processes from 19 immune markers. Logistic regression with generalized estimating equations was used to evaluate associations between inflammatory processes and depressive symptoms stratified by HIV serostatus. Three EFA-identified inflammatory processes (EIPs) were identified. EIP-1 scores-described by soluble tumor necrosis factor receptor 2 (sTNF-R2), soluble interleukin-2 receptor α (sIL-2Rα), sCD27, B-cell activating factor, interferon γ-induced protein 10 (IP-10), soluble interleukin-6 receptor (sIL-6R), sCD14, and sGP130-were significantly associated with 9% higher odds of depressive symptoms in HIV+ participants (odds ratio = 1.09; 95% confidence interval: 1.03, 1.16) and 33% higher odds in HIV- participants (odds ratio = 1.33; 95% confidence interval: 1.09, 1.61). Findings suggest that immune activation might be involved in depression risk among both HIV+ and HIV- men who have sex with men.

Biological variation of immunological blood biomarkers in healthy individuals and quality goals for biomarker tests

BACKGROUND

Cytokines, chemokines, adipocytokines, soluble cell receptors, and immune activation markers play an important role in immune responsiveness and can provide prognostic value since they reflect underlying conditions and disease states. This study was undertaken to investigate the components of biological variation for various laboratory tests of blood immunological biomarkers.

RESULTS

Estimates of intra-individual coefficient of variation (CVI) and inter-individual coefficient of variation (CVG) were examined for blood immunological biomarkers. Biomarkers with CVI < 10% for both genders were CD3, CD4, and CD8 T-cells, serum levels of soluble cluster of differentiation 14 (sCD14), sCD163, and soluble glycoprotein 130 (sgp130). The CVI for serum levels of adiponectin, interleukin-1 receptor antagonist (IL-1Ra), macrophage inflammatory protein 1 beta (MIP-1β), soluble CD40 Ligand (sCD40L), soluble interleukin-2 receptor alpha (sIL-2Rα), soluble interleukin-6 receptor (sIL-6R), soluble tumor necrosis factor receptor II (sTNF-RII), and tumor necrosis factor alpha (TNF-α) were between 11 and 20%. Biomarkers with CVG < 20% were CD3 T-cell, and serum concentrations of sCD14, sCD40L, and sgp130. The biomarkers with CVG > 40% were adiponectin, IL-1ra, leptin, MIP-1β, sCD163, and sIL-2Rα.

CONCLUSION

The biological variations of biomarkers have important monitoring value for longitudinal investigation and are essential for quality specification of tests that are performed in the laboratory. The CVI was relatively small while CVG was comparatively large and mean values of each biomarker vary between subjects. The individuality of biomarkers significantly influences reference interval values. A majority of the biomarkers in this study had strong individuality and the result of each biomarker should be cautiously interpreted if using established reference interval values. Comparison of a patient's test result with previous ones may be more useful than the usage of conventional reference values.

Inflammatory monocytes expressing tissue factor drive SIV and HIV coagulopathy

In HIV infection, persistent inflammation despite effective antiretroviral therapy is linked to increased risk of noninfectious chronic complications such as cardiovascular and thromboembolic disease. A better understanding of inflammatory and coagulation pathways in HIV infection is needed to optimize clinical care. Markers of monocyte activation and coagulation independently predict morbidity and mortality associated with non-AIDS events. We identified a specific subset of monocytes that express tissue factor (TF), persist after virological suppression, and trigger the coagulation cascade by activating factor X. This subset of monocytes expressing TF had a distinct gene signature with up-regulated innate immune markers and evidence of robust production of multiple proinflammatory cytokines, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6, ex vivo and in vitro upon lipopolysaccharide stimulation. We validated our findings in a nonhuman primate model, showing that TF-expressing inflammatory monocytes were associated with simian immunodeficiency virus (SIV)-related coagulopathy in the progressive [pigtail macaques (PTMs)] but not in the nonpathogenic (African green monkeys) SIV infection model. Last, Ixolaris, an anticoagulant that inhibits the TF pathway, was tested and potently blocked functional TF activity in vitro in HIV and SIV infection without affecting monocyte responses to Toll-like receptor stimulation. Strikingly, in vivo treatment of SIV-infected PTMs with Ixolaris was associated with significant decreases in D-dimer and immune activation. These data suggest that TF-expressing monocytes are at the epicenter of inflammation and coagulation in chronic HIV and SIV infection and may represent a potential therapeutic target.

The Initial Months of Antiretroviral Therapy and Its Influence on AGEs, HMGB1, and sRAGE Levels in Asymptomatic HIV-Infected Individuals

The development of the typical comorbidities of aging which currently affects people living with HIV/AIDS (PLWHA) can be partially ascribed to the persistent immune activation and chronic inflammation characterizing these individuals. The aim of this study was to analyze the effect exerted by combined antiretroviral therapy (cART) administration on plasma levels of HMGB1 (high mobility group box protein-1), AGEs (advanced glycation end products), their soluble receptor sRAGE, cytokines, C-reactive protein (CRP), and some metabolic markers in asymptomatic PLWHA. Analyses were performed longitudinally in 30 PLWHA, before and about 6–12 months after cART initiation. We observed that lower levels of AGEs in post-cART group were accompanied by an increase of CRP and triglyceride levels already in the early months of therapy. Because of the current ever-earlier recommendations to start cART and its prolonged use, these and other markers should be investigated in order to monitor and postpone the appearance of non-AIDS comorbidities in PLWHA.

Stability of cytokines, chemokines and soluble activation markers in unprocessed blood stored under different conditions

BACKGROUND

Biomarkers such as cytokines, chemokines, and soluble activation markers can be unstable when processing of blood is delayed. The stability of various biomarkers in serum and plasma was investigated when unprocessed blood samples were stored for up to 24h at room and refrigerator temperature.

METHODS

Blood was collected from 16 healthy volunteers. Unprocessed serum, EDTA and heparinized blood was stored at room (20-25°C) and refrigerator temperature (4-8°C) for 0.5, 2, 4, 6, 8, and 24h after collection before centrifugation and separation of serum and plasma. Samples were batch tested for various biomarkers using commercially available immunoassays. Statistically significant changes were determined using the generalized estimating equation.

RESULTS

IFN-γ, sIL-2Rα, sTNF-RII and β2-microglobulin were stable in unprocessed serum, EDTA and heparinized blood samples stored at either room or refrigerator temperature for up to 24h. IL-6, TNF-α, MIP-1β and RANTES were unstable in heparinized blood at room temperature; TNF-α, and MIP-1β were unstable in unprocessed serum at room temperature; IL-12 was unstable in unprocessed serum at refrigerator temperature; and neopterin was unstable in unprocessed EDTA blood at room temperature. IL-1ra was stable only in unprocessed serum at room temperature.

CONCLUSION

All the biomarkers studied, with the exception of IL-1ra, were stable in unprocessed EDTA blood stored at refrigerator temperature for 24h. This indicates that blood for these biomarkers should be collected in EDTA and if delays in processing are anticipated the unseparated blood should be stored at refrigerator temperature until processing.

Impact of Whole-Blood Processing Conditions on Plasma and Serum Concentrations of Cytokines

Pre-analytical variations in plasma and serum samples can occur because of variability in whole-blood processing procedures. The aim of this study was to determine the impact of delayed separation of whole blood on the plasma and serum concentrations of cytokines. The concentrations of 16 cytokines were measured in plasma and serum samples when the centrifugation of whole blood at room temperature was delayed for 4, 6, 24, or 48 h, and the values were compared with those observed after separation within 2 h of whole-blood collection. Receiver operating characteristic (ROC) curve analysis was also performed for cytokines to determine whether cytokine levels in plasma and serum samples can be used to assess delayed separation of whole blood. Plasma concentrations of interleukin (IL)-1β, granulocyte-macrophage colony-stimulating factor (GM-CSF), and soluble CD40 ligand (sCD40L) and serum concentrations of IL-1β, IL-6, IL-8, macrophage inflammatory protein-1α (MIP-1α), and MIP-1β increased significantly (>2-fold) when separation was delayed at room temperature for 24 h. The concentrations of 6 of these cytokines (all except serum IL-1β and IL-6) demonstrated high diagnostic performance (area under the ROC curve >0.8) for delayed separation of whole blood. Furthermore, these cytokine concentrations typically exhibited high sensitivity and specificity at each optimal cutoff point. Conversely, IL-17A was stable in both plasma and serum samples, even when whole-blood centrifugation was delayed at room temperature for 48 h. This study shows that certain cytokines (IL-1β, GM-CSF, sCD40L, IL-8, MIP-1α, and MIP-1β) could be used for assessing the quality of plasma or serum samples.

Methodological Issues in Cytokine Measurement in Schizophrenia

There is mounting evidence that inflammation is a major factor in the pathophysiology of schizophrenia. Inflammatory status is commonly ascertained by measuring peripheral cytokine concentrations. An issue concerning research on inflammation and schizophrenia relates to assay methodology. Enzyme-linked immunosorbent assay (ELISA) is the most widely used and the gold standard method used to measure cytokine concentrations. ELISA has a number of limitations. Both ELISA and multiplex are limited by not being able to distinguish between bioactive and inactive molecules and the matrix and heterophilic (auto-) antibody interference. Multiplex assays when combined with gene expression analysis and flow cytometry techniques such as fluorescence-activated cell sorting may be useful to detect abnormalities in specific immune pathways. Peripheral blood mononuclear cells cultures, to evaluate in vitro lipopolysaccharide-induced cytokine production, may be a better technology than measuring cytokines in the serum. The purpose of this paper is to shed light on major methodological issues that need to be addressed in order to advance the study of cytokines in schizophrenia. We make a few recommendations on how to address these issues.

Measurement of Circulating Cytokines and Immune-Activation Markers by Multiplex Technology in the Clinical Setting: What Are We Really Measuring?

Measurement of circulating cytokine levels can provide important information in the study of the pathogenesis of disease. John L. Fahey was a pioneer in the measurement of circulating cytokines and immune-activation markers and a leader in the quality assessment/control of assays for measurement of circulating cytokines. Insights into the measurement of circulating cytokines, including consideration of multiplex assays, are presented here.

Utility of Serum Neopterin and Serum IL-2 Receptor Levels to Predict Absolute CD4 T Lymphocyte Count in HIV Infected Cases

A prospective study was carried out to evaluate the efficacy of serum neopterin and soluble IL-2 receptor (sIL-2R) concentrations in comparison to CD4 count to study the progression of HIV disease and monitor response to ART in HIV cases. One hundred newly diagnosed HIV seropositive subjects were recruited. CD4 counts were determined by FACS system. Serum neopterin and sIL-2R levels were measured using enzyme immunoassay. In our study, levels of neopterin and sIL-2R were significantly higher in subjects with CD4 <200 cells/ μ L (with S. neopterin levels of >25.1 nmol/L and sIL-2R levels of >47.1 pM as cutoff values for CD4 <200 cells/ μ L) compared to those in subjects with CD4 >200 cells/ μ L at baseline which indicate that these markers can be utilized for initiation of ART in HIV cases. The levels of these markers decreased significantly after initiation of ART. In patients with CD4 >200 cells/ μ L, these markers are helpful in predicting disease progression.

Heparin and EDTA anticoagulants differentially affect the plasma cytokine levels in humans

Cytokines and chemokines are the cell signaling proteins which are considered as important biomarkers of inflammation and immunity. However the fragile nature of these markers results in the concentration variation due to various external factors. We assessed the influence of commonly used anticoagulants (EDTA and heparin) on various cytokine levels from 32 paired plasma samples using highly sensitive multiple cytokine estimation assay. Out of 17 cytokines estimated, 15 were detectable in more than 80% of the samples from both the groups. TNF-α, IFN-γ, IL-4, IL-5, and G-CSF levels were significantly higher (p values < 0.05 for all) in plasma with EDTA, whereas the levels of IL-6, IL-8, IL-10, IL-17, MIP-1β, GM-CSF and MCP-1 were found to be significantly higher (p values < 0.05 for all) in plasma with heparin. There was no significant difference in the levels of IL-7, IL-12 (P70) and IL-13 in both the groups. The study showed that the anticoagulants significantly affect the measurement of certain cytokines. Hence, it is important to choose an appropriate anticoagulant before the estimation of cytokines for reliable use of plasma cytokines as biomarkers in patient management.

HIV and malnutrition: effects on immune system

HIV or human immunodeficiency virus infection has assumed worldwide proportions and importance in just a span of 25 years. Continuous research is being done in many parts of the world regarding its treatment and vaccine development, and a lot of money has flown into this. However, fully understanding the mechanisms of immune depletion has still not been possible. The focus has also been on improving the quality of life of people living with HIV/AIDS through education, counselling, and nutritional support. Malnutrition further reduces the capacity of the body to fight this infection by compromising various immune parameters. Knowledge of essential components of nutrition and incorporating them in the management goes a long way in improving quality of life and better survival in HIV-infected patients.

Endometrial epithelial cell responses to coinfecting viral and bacterial pathogens in the genital tract can activate the HIV-1 LTR in an NF{kappa}B-and AP-1-dependent manner

BACKGROUND

Sexually transmitted infections (STIs) are associated with increased human immunodeficiency virus type 1 (HIV-1) susceptibility and viral shedding in the genital tract, but the mechanisms underlying this association are poorly understood.

METHODS

Direct activation of HIV long terminal repeats (LTRs), a proxy measure for HIV-1 replication, was measured after treatment of 1G5 T cells with Toll-like receptor (TLR) ligands, herpes simplex virus type 1 or 2 (HSV-1/2), or Neisseria gonorrhoeae. For indirect activation, 1G5 T cells were incubated with supernatants from female primary genital epithelial cells (GECs) previously exposed to these agents. Proinflammatory cytokines and chemokines were measured in GEC supernatants. Proinflammatory pathways were blocked to determine the mechanisms of direct and indirect HIV-LTR activation.

RESULTS

HSV-1/2, N. gonorrhoeae, and TLR ligands FimH (TLR-4), flagellin (TLR-5), and Poly (I:C) (TLR-3) directly induced HIV-LTR activation in 1G5 T cells. Supernatants collected from GECs incubated with these agents indirectly induced HIV-LTR activation. Production of tumor necrosis factor α, interleukin 6, interleukin 8, and monocyte chemoattractant protein-1 was elevated in GECs exposed to copathogens. Inhibition of nuclear factor κB and activator protein-1 (AP-1) signaling pathways in 1G5 T cells abrogated both direct and indirect HIV-LTR activation.

CONCLUSIONS

STIs may increase HIV-1 replication in the female genital tract via proinflammatory signaling pathways directly and indirectly via their effects on GECs. This increased HIV-1 replication may enhance sexual and vertical HIV transmission.

Long-term non-progressors display a greater number of Th17 cells than HIV-infected typical progressors

Interleukin 17 (IL17) secreting T (Th17) cells play a protective role against bacterial infections at mucosal surfaces. Recent reports show Th17 cells are depleted in the gut associated lymphoid tissue of HIV+ patients, but their role in HIV disease progression is not well understood. Expression of the IL17 receptor (IL17R) and the production of IL17 were compared between two groups of HIV patients with different disease progression (long-term-nonprogressors, LTNP and typical-progressors, TP). IL17R expression was similar in LTNP and TP, whereas Th17 cell number was greater in LTNP than TP (p=0.015). An inverse correlation between the plasma HIV-RNA and both IL17R expression and Th17 cell number was found (p=0.001 and p=0.002, respectively). The increased number of Th17 cells in LTNP could lead to a more preserved immune response against bacterial infections. As a result, lower microbial translocation could explain the reduced immune activation and slower disease progression seen in LTNP.

Pretreatment levels of soluble cellular receptors and interleukin-6 are associated with HIV disease progression in subjects treated with highly active antiretroviral therapy

BACKGROUND

To identify inflammatory pathways that may contribute to the pathogenesis of human immunodeficiency virus (HIV) disease, we explored associations between AIDS or death and different inflammatory markers, including selected soluble tumor necrosis factor superfamily receptors (sTNFRs) and ligands, interleukin (IL)-6, and CD8 T cell activation, in individuals treated with highly active antiretroviral therapy (HAART).

METHODS

A case-control study of subjects in AIDS Clinical Trials Group (ACTG) protocols 384 and 5015, who were matched according to the CD4 cell count and plasma viral load at baseline, was performed using conditional logistic regression.

RESULTS

Higher pretreatment concentrations of sTNFR-1, sCD27, sCD40L, and plasma IL-6 were associated with a new AIDS-defining illness or death in separate models adjusted for age, sex, hemoglobin, and the latest CD4 cell counts. In additional models that excluded case patients with opportunistic infections, sTNFR-1, sCD27, and sCD40L were each associated with a new AIDS-defining malignancy or death that developed at a median of 51 weeks after initiation of HAART, by which time the majority of subjects had a CD4 cell count of >200 cells/cm(3) and had achieved a plasma viral load of <50 copies/mL.

CONCLUSION

These data are compatible with a model in which these soluble inflammatory markers identify pathways that may contribute to the pathogenesis of HIV disease progression, pathways that might not be a direct consequence of ongoing HIV type 1 replication.

Validation and comparison of two multiplex technologies, Luminex and Mesoscale Discovery, for human cytokine profiling

Biomarker research has rapidly expanded over recent years aided by the progressive development of research tools, in particular the different multiplex technologies allowing simultaneous measurement of multiple analytes. It is foreseeable that such technology will have an integral role in clinical studies for establishing biomarker profiles of disease status, but validation of the tools is essential to confirm the reliability of their application. More comparable studies between multiplex platforms are required to enable users to determine which of these are best for a particular clinical study, as different platforms will have varying levels of performance for the validation parameters. Comparison of two multiplex platforms, the Luminex and the Mesoscale Discovery, has been performed to determine their performance for the validation parameters of sensitivity, precision and accuracy for the cytokines IL-2, IL-4, IL-8, IL-10, IL-12, IFNgamma and TNFalpha. When measuring high concentrations both platforms show good accuracy (within +/-25% recovery) with all cytokines except IL-12 for the MSD. At low concentrations, +/-25% recovery was seen with all cytokines except IL-2 and IL-8 for the Luminex and IL-2 and IL-12 for the MSD. Although quantitative differences are found, relative differences are comparable, and consequently both platforms have been shown to be suitable for analyzing trends in multiple cytokine profiles, with the Luminex having better precision and the Mesoscale Discovery having greater sensitivity.

Differential Th17 CD4 T-cell depletion in pathogenic and nonpathogenic lentiviral infections

Acute HIV infection is characterized by massive loss of CD4 T cells from the gastrointestinal (GI) tract. Th17 cells are critical in the defense against microbes, particularly at mucosal surfaces. Here we analyzed Th17 cells in the blood, GI tract, and broncheoalveolar lavage of HIV-infected and uninfected humans, and SIV-infected and uninfected sooty mangabeys. We found that (1) human Th17 cells are specific for extracellular bacterial and fungal antigens, but not common viral antigens; (2) Th17 cells are infected by HIV in vivo, but not preferentially so; (3) CD4 T cells in blood of HIV-infected patients are skewed away from a Th17 phenotype toward a Th1 phenotype with cellular maturation; (4) there is significant loss of Th17 cells in the GI tract of HIV-infected patients; (5) Th17 cells are not preferentially lost from the broncheoalveolar lavage of HIV-infected patients; and (6) SIV-infected sooty mangabeys maintain healthy frequencies of Th17 cells in the blood and GI tract. These observations further elucidate the immunodeficiency of HIV disease and may provide a mechanistic basis for the mucosal barrier breakdown that characterizes HIV infection. Finally, these data may help account for the nonprogressive nature of nonpathogenic SIV infection in sooty mangabeys.

Use of surrogate markers to predict the HIV disease stage and time to initiate antiretroviral therapy in developing countries

CD4 counting is the standard method for determining eligibility for antiretroviral therapy (ART) and HIV disease progression, but it is not widely available in developing countries. The aim of this study was to correlate the levels of beta-2 microglobulin and total lymphocyte count (TLC) with CD4 counts for monitoring disease progression and identify patients who require ART. The authors measured CD4 T-cell counts, TLC, and beta-2 microglobulin levels in 119 HIV seropositive patients. There was a significant negative correlation between CD4 counts and beta-2 microglobulin levels and significant positive correlation between TLC and CD4 counts. Taking a TLC cutoff of < or = 1600 and beta-2 microglobulin levels > or = 3.5 mg/l, the authors could identify 90.4% of patients with CD4 count < or = 200 cells/microl. These assays may allow reduction in the annual number of CD4 cell evaluation and the cost associated with monitoring the immune status of HIV-positive patients.

Co-infection with subclinical HIV and Wuchereria bancrofti, and the role of malaria and hookworms, in adult Tanzanians: infection intensities, CD4/CD8 counts and cytokine responses

The association between HIV and Wuchereria bancrofti, and the role of malaria and hookworms, were analysed by comparing three groups of individuals with: (1) HIV (HIV+; n=16); (2) W. bancrofti (circulating filarial antigen (CFA)+; n=25); and (3) HIV and W. bancrofti (HIV+/CFA+; n=18). A slightly higher HIV load and lower CD4% was observed in the HIV+/CFA+ group compared with the HIV+ group, and a slightly higher W. bancrofti CFA intensity was observed in the CFA+ group compared with the HIV+/CFA+ group, but none of these differences were statistically significant. Specific and non-specific IL-4, IL-10, IFNgamma and TNF levels were measured. Only specific IL-4 was significantly higher in the CFA+ group compared with the HIV+/CFA+ group. Thus, there was no clear evidence for an interaction between HIV and W. bancrofti infection. A multiple linear regression model showed that the presence of CFA was strongly positively associated with specific TNF response and, similarly, that HIV-positive individuals had higher TNF responses than HIV-negative individuals. Interestingly, the CD4% and CD4/CD8 ratio were higher in HIV-positive individuals with hookworms than in those without hookworm co-infection. Malaria was not associated with any of the other infections, or with CD4/CD8 counts or cytokine responses.

Cardiac isoform of alpha 2 macroglobulin, an early diagnostic marker for cardiac manifestations in AIDS patients

This study investigated the possible role of the cardiac isoform of alpha 2-macroglobulin (CA2M) as an early diagnostic marker for HIV-associated cardiovascular manifestations. A total of 349 samples were analysed by Western blot and quantified by sandwich enzyme-linked immunosorbent assay. The levels of CA2M present in sera of HIV-associated cardiac diseases were significantly higher than those of HIV without cardiac involvement and healthy sera. CA2M may act as a novel diagnostic marker to identify cardiac manifestations in HIV/AIDS patients.

Cross-sectional relationship between HIV, lymphatic filariasis and other parasitic infections in adults in coastal northeastern Tanzania

The relationship between HIV, lymphatic filariasis, malaria (Plasmodium falciparum) and intestinal helminths (Ascaris lumbricoides, Trichuris trichiura and hookworm) was assessed in a cross-sectional study conducted in 2002 among 907 adults in Tanga Region, Tanzania. Overall prevalences were 7.9% for HIV, 43.5% for Wuchereria bancrofti-specific circulating filarial antigen (CFA), 12.3% for P. falciparum, 1.2% for A. lumbricoides, 7.1% for T. trichiura and 75.7% for hookworm. Anaemia was assessed separately for males and females and was found to be more prevalent among females (58.8%) than males (34.8%). When sex and age were controlled for, there was a statistically significant positive association between HIV and W. bancrofti (CFA) infection and between malaria and HIV, but not between malaria and W. bancrofti (CFA) infection. Hookworm infection was positively associated with W. bancrofti (CFA) infection but, surprisingly, negatively associated with HIV. Infection with HIV and hookworms, but not malaria, was associated with a significant reduction in haemoglobin concentration. These associations are likely to reflect underlying mechanisms that need to be clarified to better understand the role of co-infections in HIV pathogenesis, and vice versa.

Different profile of cytokine synthesis according to the severity of acute pancreatitis

AIM: To evaluate the cellular synthetic ability of cytokines involved in pro- and anti-inflammatory reactions in patients with AP.

METHODS: Sixty-seven patients with AP (16 severe, 51 mild) and 10 controls were included in the study. Cultures of whole blood were performed in samples obtained within the first 72 h from the onset of pain. Serum levels of interleukins (IL) 6, 8, 10, and TNF-α were measured at baseline and in the supernatant of cultures with (functional reserve) or without stimulation with phytohemaglutinin.

RESULTS: Basal levels of cytokines were significantly higher in patients with severe AP. A significant increase of all pro-inflammatory cytokines vs basal levels was observed in the supernatant after 24 h of whole blood cultures in patients, but not in controls. In contrast, IL-10 increased significantly in the supernatant of cultures only in patients with mild AP. Cells showed a statistically significant functional reserve for all IL in patients with mild, but only for pro-inflammatory cytokines in patients with severe AP.

CONCLUSION: A marked activation of immune system may be observed in patients with AP, being balanced between pro- and anti-inflammatory cytokines in patients with mild but not severe AP. A reduced functional reserve for the synthesis of IL-10 may be observed in patients with severe AP, which might lead to a worst prognosis.

Serum Neopterin, an Immune Activation Marker, Independently Predicts Disease Progression in Advanced HIV-1 Infection

BACKGROUND

CD4+ T lymphocyte (CD4) counts and plasma human immunodeficiency virus (HIV) type 1 RNA concentrations predict clinical outcome in HIV-1 infection. Our objective was to assess the independent prognostic value for disease progression of soluble markers of immune system activation.

METHODS

This retrospective marker-validation study utilized previously obtained clinical and laboratory data, including CD4+ cell counts, and made use of stored frozen serum samples to assay for levels of beta2-microglobulin, neopterin, endogenous interferon, triglycerides, interleukin-6, soluble tumor necrosis factor- alpha receptor II, and HIV-1 RNA, and to determine HIV genotypic reverse-transcriptase inhibitor resistance. The 152 patients who participated in this study represented a subsample of participants in AIDS Clinical Trials Group (ACTG) 116B/117, a randomized trial that demonstrated the clinical benefit of didanosine over zidovudine monotherapy in persons with advanced HIV-1 infection. Marker data were analyzed in relation to protocol-defined clinical disease progression, using Cox proportional hazards models.

RESULTS

The median duration of follow-up was 344 days. Elevated baseline values for neopterin (P=.0009), endogenous interferon (P=.00039) and interleukin-6 (P=.0007) were each associated with greater subsequent risk of clinical disease progression. In a head-to-head comparison that was adjusted for CD4+ cell count (P=.0165) and HIV-1 RNA level (P=.1220), we found that elevated values for neopterin (P=.0002) and, to a lesser extent, endogenous interferon (P=.0053) were the strongest predictors of increased risk of clinical disease progression 6 months later.

CONCLUSIONS

Soluble markers of immune activation add prognostic information to CD4 counts and viral load for risk of disease progression in advanced HIV-1 infection. The robust performance of neopterin, an inexpensive and reliably measured serum marker, supports its potential suitability for patient monitoring, particularly in resource-limited settings.

HIV alters plasma and M. tuberculosis-induced cytokine production in patients with tuberculosis

To test the hypothesis that HIV infection brings about an alteration in the immune response to tuberculosis (TB), mycobacterial antigen-induced production and plasma levels of the inflammatory cytokine interferon-gamma (IFN-gamma) and its regulatory cytokines interleukin-12 (IL-12), IL-18, and IL-10 were determined in patients infected dually with HIV and TB and compared with individuals with either disease and with healthy controls. Peripheral blood mononuclear cells (PBMCs) of TB patients with HIV infection produced lesser amounts of IFN-gamma and IL-12 compared with TB patients without HIV infection after in vitro stimulation with mycobacterial antigens. There was no difference in antigen-induced IL-18 production in TB patients with or without HIV infection. The in vivo cytokine pattern did not correlate with that seen in vitro. Higher levels of IFN-gamma, IL-12, and IL-18 were detected in the plasma of TB patients infected with HIV compared with TB patients without HIV infection. The presence of significantly higher plasma levels of proinflammatory cytokines suggests a greater degree of immune activation in individuals with HIV and TB, particularly those with low CD4 counts. In vitro IL-10 production by HIV-positive TB patients was similar to that of the HIV-negative TB group and higher than in HIV-positive individuals without TB, but the plasma levels were similar. HIV infection downregulates the in vitro Th1 cytokine response to TB and simultaneously increases systemic levels of these cytokines.

Can immune markers predict subsequent discordance between immunologic and virologic responses to antiretroviral therapy? Adult AIDS Clinical Trials Group

It is unclear why discordant immunologic and virologic responses occur during therapy for human immunodeficiency virus (HIV) infection. This study examined whether markers of immune activation and naive/memory lymphocyte subsets at study baseline could predict discordance between HIV type 1 (HIV-1) RNA and CD4+ lymphocyte responses at week 24 of antiretroviral therapy. Ten diverse, prospective antiretroviral studies with 1007 evaluable subjects were included. Subsets of subjects at increased risk for discordance were identified by recursive partitioning. The strongest predictor of more-favorable immunologic than virologic responses was a lower baseline CD4+ lymphocyte count. Weaker predictors in small subsets of subjects were fewer activated CD4+ lymphocytes and fewer CD8+ lymphocytes. Conversely, the strongest predictors of more-favorable virologic than immunologic responses were higher baseline CD4+ lymphocyte count and percentage. Additional predictors in some analyses were higher CD8+ lymphocyte count or percentage and lower HIV-1 RNA concentrations. Baseline markers of immune activation and naive/memory lymphocyte subsets had limited ability to predict subsequent discordance.

Effects of an exercise intervention on immunologic parameters in frail elderly nursing home residents

BACKGROUND

Aging is associated with decline in both cell-mediated and humoral immunity and may contribute to increased incidence and severity of infections in frail elderly. Exercise, depending on intensity, has significant effects on the immune system. We conducted a randomized, controlled clinical trial of a 32-week functionally oriented exercise program in frail elderly living in nursing homes and determined whether the exercise intervention was associated with a change in immune parameters in this frail elderly nursing home population.

METHODS

Nursing home residents were randomly assigned to an intervention (n = 94) and control group (n = 96). The intervention consisted of a functionally oriented endurance and resistance exercise training that was provided every 2 hours from 8:00 AM to 4:00 PM for 5 days a week for 8 months. Lymphocyte subpopulations, including activation markers (CD28, CD25, HLA-DR), in vitro proliferation, and soluble products of cytokine activity (neopterin and sTNF-RII) in serum were measured by taking blood samples at baseline and after 8 weeks and 32 weeks of the intervention.

RESULTS

Exercise training did not induce changes in lymphocyte subpopulations, activation markers (CD28, CD25, HLA-DR), in vitro proliferation, and soluble products of cytokine activity (neopterin and sTNF-RII) in serum.

CONCLUSIONS

A 32-week exercise intervention did not bring about beneficial or detrimental effects on immune parameters in the frail elderly nursing home population and may explain why the intervention was not associated with a change in the incidence of infections in the intervention group compared with the control group.

Leishmaniasis in HIV infection

Herein we review the particular aspects of leishmaniasis associated with HIV infection. The data in this review are mainly from papers identified from PubMed searches and from papers in reference lists of reviewed articles and from the authors' personal archives. Epidemiological data of HIV/Leishmania co-infection is discussed, with special focus on the influence of Highly Active Antiretroviral Therapy (HAART) on incidence of leishmaniasis and transmission modalities. Microbiological characteristics, pathogenesis, clinical presentation and specific treatment of the co-infection are also presented.

Fatigue and proinflammatory cytokine activity in breast cancer survivors

OBJECTIVE

Fatigue is a common problem among cancer patients and survivors, yet the mechanisms underlying the occurrence and persistence of this symptom are not known. Activation of the immune system may evoke feelings of fatigue, which are mediated by proinflammatory cytokines. We examined whether fatigued breast cancer survivors would show elevations in proinflammatory cytokines and markers of cytokine activity compared with nonfatigued survivors. Differences in lymphocyte subsets, cortisol, and behavioral symptoms associated with proinflammatory cytokines were also assessed.

METHODS

Forty breast cancer survivors (20 fatigued, 20 nonfatigued) provided blood samples at visits scheduled to control for diurnal variability. Cytokines, soluble markers of cytokine activity, and cortisol were measured by immunoassay and lymphocyte subsets by flow cytometry. Participants also completed questionnaires measuring demographic, medical, and behavioral variables.

RESULTS

Fatigued breast cancer survivors had significantly higher serum levels of several markers associated with proinflammatory cytokine activity than nonfatigued survivors, including interleukin-1 receptor antagonist (IL-1ra), soluble tumor necrosis factor receptor type II (sTNF-RII), and neopterin. They were also more likely to report behavioral problems that co-occur with fatigue in the context of immune activation. Fatigued survivors had significantly lower serum levels of cortisol than the nonfatigued group as well as differences in two lymphocyte populations.

CONCLUSIONS

Fatigued breast cancer survivors showed elevations in serum markers associated with proinflammatory cytokine activity an average of 5 years after diagnosis. Results suggest mechanisms through which enduring immune activation may occur, including alterations in cortisol and in lymphocyte subsets.

Plasma levels of soluble CD27: a simple marker to monitor immune activation during potent antiretroviral therapy in HIV-1-infected subjects

Plasma levels of soluble CD27 (sCD27) are elevated in diseases characterized by T cell activation and are used as a marker of immune activation. We assessed the usefulness of determining plasma sCD27 as a marker for monitoring immune activation in HIV-1-infected patients treated with highly active antiretroviral therapy (HAART). A first cross-sectional examination of 68 HIV-1-infected and 18 normal subjects showed high levels of sCD27 in HIV-1 infection; plasma sCD27 was correlated to HIV-1 viraemia and inversely correlated to CD4+ T cell count. Twenty-six HIV-1-infected patients undergoing HAART were studied at baseline and after 6, 12, 18 and 24 months of therapy. Seven additional patients under HAART were analysed at baseline, during and after interruption of therapy. In the total population, HAART induced a significant and progressive reduction, but not a normalization, of plasma levels of sCD27 after 24 months. A full normalization of plasma sCD27 was observed in the virological responders (undetectable HIV-1 RNA at months 18 and 24) and also in patients with moderate immunodeficiency at baseline (CD4+ T cell count >200 cells/mm3). Changes in plasma neopterin paralleled the changes in sCD27 but only baseline sCD27 levels were predictive of a greater increase in CD4+ T cell count during the follow-up. Discontinuation of therapy resulted in a rapid increase of sCD27 plasma levels associated with viraemia rebound and drop in CD4+ T cell count. Our findings suggest that plasma sCD27 may represent an alternative and simple marker to monitor immune activation during potent antiretroviral therapy. HIV-1-induced immune activation can be normalized by HAART in successfully treated patients where the disease is not advanced.

Effect of anti-IL-6 and anti-10 monoclonal antibodies on the suppression of the normal T lymphocyte mitogenic response by steady state sickle cell disease sera

Previously published work has shown that sera from healthy sickle cell disease (SCD) patients inhibits normal lymphocyte mitogenic response to phytohemagglutinin (PHA) in vitro. The current study is to attempt to ascertain what effect antibody to type 2 cytokines, interleukin (IL)-6 and 10, have on the suppression of lymphocyte PHA response by SCD sera. Peripheral blood mononuclear cells (PBMC), separated by density gradient were obtained from 2 healthy normal donors. Sera from 50 healthy SCD patients, 50 normal healthy controls and pooled normal O, Rh+ (O+) sera were utilized in standard in vitro PHA stimulation of PBMC cultures. Mitogenic responses were expressed as mean counts per minute (cpm) of triplicate cultures. Fifty triplicate cultures of PHA stimulated normal PBMC were done with 10% normal pooled O+, normal control and SCD steady state sera only. In addition 50 cultures were done with SCD sera containing 1 microg/ml of anti-IL-6 monoclonal antibody, as well as 28 SCD serum cultures containing 1 microg/ml of anti-IL-10 monoclonal antibody. The final 11 SCD serum culture experiments contained a combination of both anti-IL-6 and anti-IL-10 antibody, each at the concentration of 1 microg/ml. Results revealed > 15% suppression of mitogenic response in the SCD sera supplemented cultures as compared to control sera in 47/50 (94%) and in 40/50 (80%) of normal pooled O+, as calculated by mean cpm. The degree of suppression ranged from 17% to 98% in individual experiments. The addition of anti IL-6 antibody alone significantly improved mean cpm (> 20%) in 19/50 (38%) of SCD serum responses compared to O+ sera and 23/50 (46%) of control sera. Complete correction occurred in 9/50 (18%) of all SCD serum suppressions as compared to O+ sera and 6/50 (12%) when compared to control sera. Similarly, anti-IL-10 antibody decreased suppression of the mean cpm of SCD serum cultures in 18/28 (64%) and completely corrected 3/18 (11%). The combined antibody data revealed >20% increase in mean cpm in 10/11(91%) experiments. Inhibitors of mitogenic response were present in a significant percentage of the SCD sera utilized in the present study. The significant corrective effects of both monoclonal antibodies would seem to support the original hypothesis that high circulating levels of type 2 cytokines may represent the cell-mediated dependent inhibitory factors expressed in the sera of many healthy SCD patients.

Macrophage activation by antiviral acyclic nucleoside phosphonates in dependence on priming immune stimuli

Acyclic nucleoside phosphonates (ANPs) are potent broad-spectrum antivirals, also effective against immunodeficiency viruses and hepatitis viruses. Effects of several ANPs on in vitro cytokine gene expression and nitric oxide (NO) production by murine peritoneal macrophages were investigated. Included in the study were 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA; Adefovir), 9-(R)-[2-(phosphonomethoxy)propyl]adenine [(R)-PMPA; Tenofovir], 9-(S)-[2-(phosphonomethoxy)propyl]adenine; (S)-PMPA), 9-[2-(phosphonomethoxy)ethyl]-2,6-diaminopurine (PMEDAP), 9-(R)-[2-(phosphonomethoxy)propyl]-2,6-diaminopurine (PMPDAP), and 9-[2-(phosphonomethoxy)ethyl]guanine (PMEG). Some of them, i.e. (R)-PMPA, (S)-PMPA, and PMEG, stimulate secretion of TNF-alpha and IL-10 in a concentration-dependent manner, and enhance the IFN-gamma-induced secretion of TNF-alpha. Although unable to activate production of nitric oxide (NO) on their own, these compounds substantially augment NO formation induced by IFN-gamma. Analysis of the expression of inducible NO synthase mRNA indicates that the NO-enhancing effect of ANPs is mediated posttranscriptionally. In contrast to IFN-gamma, production of NO triggered by lipopolysaccharide (LPS) alone, or synergistically by LPS+IFN-gamma, remains unaltered by ANPs. The immunomodulatory effects have been differentially expressed in distinct genotypes of inbred strains of mice, including the low NO-responders Balb/c and high NO-responders C3H/HeN. Although less effectively, PMEG and (R)-PMPA also increase production of TNF-alpha and NO by the IFN-gamma- but not LPS-co-stimulated macrophages from C3H/HeJ mice, which are otherwise hypo-responsive to major immune stimuli provided by IFN-gamma and LPS. It can be concluded that the expression of immunomodulatory properties of ANPs depends on the immune state of cells and its activation by distinct priming signals.

Cytokine gene expression occurs more rapidly in stimulated peripheral blood mononuclear cells from human immunodeficiency virus-infected persons

Evaluation of cytokine gene expression following in vitro stimulation is one means of examining the dysregulation of the immune system in human immunodeficiency virus (HIV) infection. We have assessed differences in the immune status of non-HIV-infected (HIV-) and HIV-infected (HIV+) individuals by evaluating the kinetics of the expression of cytokine genes. We compared detailed time courses of cytokine mRNA expression in HIV- and HIV+ peripheral blood mononuclear cells (PBMC) and found that there is a significant shift (P<0.01) for all cytokines examined (interleukin 2 [IL-2], IL-6, IL-10, gamma interferon, and tumor necrosis factor alpha [TNF-alpha]) to an earlier time of mean peak mRNA expression by HIV+ PBMC (between 4 and 8 h) compared to HIV- PBMC (8 h) in response to either phytohemagglutinin (PHA) or anti-CD3 stimulation. Additional studies showed that although PHA-stimulated HIV+ PBMC showed decreased median IL-2, IL-4, and TNF-alpha mRNA levels, they typically demonstrated more rapid kinetics (increased mean 4-h/24-h cytokine mRNA ratios), with significant differences for IL-4 (P<0.05) and TNF-alpha (P<0.005), compared to HIV- PBMC. The use of fresh or frozen cells gave comparable cytokine mRNA data; however, the secretion of some cytokine proteins (IL-2 receptor, IL-10, and TNF-alpha) appeared to be reduced in HIV+ PBMC that had been frozen and thawed. Our studies demonstrate that the kinetics of cytokine gene expression can reveal additional dysregulation of the immune system in HIV infection, suggesting that PBMC of HIV-infected persons exist in an activated state in vivo that permits them to express cytokine genes more rapidly than a normal PBMC.

Need for an external proficiency testing program for cytokines, chemokines, and plasma markers of immune activation

An external evaluation program for measuring the performance of laboratories testing for cytokines and immune activation markers in biological fluids was developed. Cytokines, chemokines, soluble cytokine receptors, and other soluble markers of immune activation (CSM) were measured in plasma from a healthy human immunodeficiency virus (HIV)-seronegative reference population and from HIV-seropositive individuals as well as in supernatant fluids from in vitro-stimulated human immune cells. The 14 components measured were tumor necrosis factor (TNF) alpha, gamma interferon, interleukin-1 (IL-1), IL-2, IL-4, IL-6, IL-10, Rantes, MIP-Ia, MIP-Ibeta, soluble TNF receptor II, soluble IL-2 receptor alpha, beta(2)-microglobulin, and neopterin. Twelve laboratories associated with the Adult and Pediatric AIDS Clinical Trial Groups participated in the study. The performance features that were evaluated included intralaboratory variability, interlaboratory variability, comparison of reagent sources, and ability to detect CSM in the plasma of normal subjects as well as the changes occurring in disease. The principal findings were as follows: (i) on initial testing, i.e., before participating in the program, laboratories frequently differed markedly in their analytic results; (ii) the quality of testing of a CSM in individual participating laboratories could be assessed; (iii) most commercial kits allowed distinction between normal and abnormal plasma CSM levels and between supernatants of stimulated and unstimulated cells; (iv) different sources of reagents and reference standards frequently provided different absolute values; (v) inexperienced laboratories can benefit from participating in the program; (vi) laboratory performance improved during active participation in the program; and (vii) comparability between analyses conducted at different sites can be ensured by an external proficiency testing program.

Distinct categories of immunologic changes in frail elderly

Immune changes and their relationships in a frail elderly population (N=116, age 70-103, median 86 years) were defined in comparison to a healthy younger group. Previous immune studies in the elderly have generally focused on one or few parameters without correlation analyses. Furthermore, the study populations have been active elderly in relatively small numbers. A total of 33 immune parameters representing many aspects of the immune system were quantified. Most changes in the frail elderly were parallel to those reported in active elderly. A classification tree analysis revealed that increased plasma activation markers (neopterin and sTNF-R) and increased CD28 expression on CD8 T cells and proliferative response separated the aged and control populations. Statistical procedures utilizing principal components analyses, partial correlations and exploratory factor analyses all indicated that immunologic parameters in frail elderly are grouped in three major clusters of immunologic results. These involved (a) increased plasma levels of neopterin and sTNF receptor indicating elevated IFNgamma and TNF cytokine activity; (b) increased proportion of mature (CD45RO) versus naïve (CD45RA) T cells; and (c) a diverse group of related changes including impaired proliferative response, reduced T cells, CD28 and CD25 expression, B cell percentage and lower CD4:CD8 ratios and increased HLA-DR expression. These findings emphasize that several different groups of immune parameters but not 33 independent immune changes, occurred in the aged population.

Immunomodulatory effect of pentoxifylline during human allograft rejection: involvement of tumor necrosis factor-alpha and adhesion molecules

BACKGROUND

Pentoxifylline (PTX), a methylxanthine phosphodiesterase inhibitor, is poorly active as an immunosuppressant but prevents the synthesis of proinflammatory cytokines. In a randomized double-blind study comparing PTX versus placebo in 140 patients receiving cadaveric kidney grafts under cyclosporine and prednisone, we have shown that PTX weakened the consequences of rejection on graft survival. To assess the mechanism underlying the beneficial effect recorded during this trial, we analyzed the impact of PTX on tumor necrosis factor (TNF-alpha) production and expression of cell adhesion molecules.

METHODS

Plasma levels of TNF-alpha and its soluble receptors (sTNF-RI, sTNF-RII) and of soluble vascular cell adhesion molecule 1 (sVCAM-1) were monitored over the 6 months postgraft period when PTX or placebo were administered. Expression of VCAM-1 and intercellular cell adhesion molecule 1 was scored by immunohistochemical staining of biopsy specimens from patients who underwent rejection crisis. Lymphocyte subset composition was analyzed longitudinally during cytomegalovirus (CMV) infections.

RESULTS

Plasma TNF-alpha levels were significantly reduced in the PTX-treated group over the 6 months of administration, and specifically during isolated rejection episodes and during CMV infections. Plasma levels of sTNFR-I, sTNFR-II, and sVCAM-1 did not differ between the two groups of patients, but a decrease in renal tubular VCAM-1 expression was observed in the PTX group. During CMV infections, CD8 lymphocytosis and expansion of CD57+ (CD28-) CD8+ T cells were similar in the two groups.

CONCLUSION

The data collected during this double-blind study point to an immunomodulatory role of PTX, the beneficial effect on graft survival resulting from a restraining effect of the drug on the inflammatory conditions involved in acute graft rejection.

In vivo production of type 1 cytokines in healthy sickle cell disease patients

Interleukins (IL)-1, 2, 12, and interferon (IFN)-gamma, along with soluble IL-2 receptor (sIL-2R) were measured from sera obtained from healthy sickle cell disease (SCD) patients and comparable healthy control subjects. The cytokines were assessed by enzyme-linked immunosorbent assay (ELISA) in 60 SCD patients and 58 controls. No significant detectable levels of IL-1 or IL-12 were found in the sera of either group of patients. Significantly elevated levels of IFN-gamma were measured in 20 (33%) of 60 SCD patients and 21 (36%) of 58 controls. A large subset of 18 (41%) of 43 healthy controls and a smaller subset of 12 (21%) of 58 SCD demonstrated detectable levels of IL-2. The sIL-2R levels of the SCD group (4465 +/- 552 pg/mL) were significantly higher (P < .0001) than that of controls (3473 +/- 411 pg/mL). The results revealed comparable circulating levels of all type 1 cytokines in both healthy SCD and normal control subjects, with the exception of in vivo sIL-2R production. Elevated serum levels of both IL-6 and tumor necrosis factor (TNF)-alpha have been reported previously in a significant percentage of SCD steady-state subjects. These two cytokines are known to increase sIL-2R expression and may help explain the difference between the patient populations. Immune activation markers such as sIL-2R are produced by cells that mediate host responses to infection or inflammatory stimuli. The implication of higher levels of sIL-2R in SCD is not clear, but chronic parvovirus B19 infection, chronic polyclonal activation of B cells or defective regulation of antibodies are possible explanations for the elevated levels in SCD.

Kinetics of lymphokine production in HIV+ patients treated with highly active antiretroviral therapy and interleukin 2

This study presents the kinetics of CD4/CD25 cell numbers, serum sCD25 levels, and intracellular production and release of interleukin-2 (IL-2) and interleukin-16 (IL-16) in 11 HIV+ patients treated with six cycles of highly active antiretroviral therapy (HAART) plus six MUI of subcutaneous IL-2 compared to 10 HIV+ patients treated with HAART alone. IL-2 therapy induced moderate effects on CD4 T cell recovery and increased CD4/CD25+ cells and sCD25 levels after 2 weeks, while intracellular and secreted IL-2 was reduced and IL-16 was increased at the same time point. After 24 weeks, while HAART-treated patients had increased IL-2 production, in IL-2 treated patients, cytokine production was unaltered compared to pretreatment values. Decreased in vitro IL-2 production may depend on a feedback inhibition by IL-2 infusion. Because of its known antiviral effects, the increased IL-16 production seen after 2 weeks in IL-2-treated individuals may produce beneficial effects on HIV disease. The kinetics of cytokine production may serve to define better the use IL-2 in clinical trials.

The prognostic significance in HIV infection of immune activation represented by cell surface antigen and plasma activation marker changes

One hundred and eighteen HIV-infected homosexual men without AIDS and 40 control seronegative homosexual men were assessed for 23 parameters reflecting immune activation to determine prognostic significance for occurrence of AIDS. Samples cryopreserved in 1987-1989 were analyzed, with AIDS occurrence determined by mid-1992. Cell surface antigens assessed on the major lymphocyte subsets were HLA-DR, CD38, CD71, and CD25. Soluble serum molecules assessed were tumor necrosis factor alpha, soluble TNFalpha receptor II, soluble IL-2 receptor alpha, neopterin, and beta2-microglobulin. Using a proportional hazards model, prognostic markers included decreased CD4 number and percentage; increased sIL-2R, neopterin, and beta2M; increased percentage HLA-DR+ total lymphocytes and CD4+ cells; increased CD38+ total lymphocytes and CD8+ cells; increased CD71+ total lymphocytes and CD4+ cells; and decreased CD25+ total lymphocytes and CD19+ cells. After adjustment for CD4 cell levels, sIL-2R, neopterin, beta2M, and CD25+ CD19 cells remained significant, indicating that additional information about AIDS risk was provided by these markers.

Variables that affect assays for plasma cytokines and soluble activation markers

Cytokines and soluble immune activation markers that reflect cytokine activities in vivo are increasingly being measured in plasma, serum, and other body fluids. They provide useful diagnostic and prognostic information as well as insight into disease pathogenesis. Assays of neopterin, beta2-microglobulin, soluble interleukin-2 receptor, and soluble tumor necrosis factor receptor type II as well as of the cytokines tumor necrosis factor alpha and gamma interferon (IFN-gamma) were evaluated by using serum and plasma samples of human immunodeficiency virus (HIV)-positive and HIV-negative subjects. Many factors were found to influence the outcomes of these assays. Substantial differences in apparent levels of analytes were frequently found when enzyme-linked immunosorbent assay (ELISA) kits from different manufacturers were used. In some cases, differences were found in the standards provided by separate manufacturers. Furthermore, the analytic results from different lots of ELISA kits supplied by single manufacturers differed by as much as 50%. The need for uniformity in the standards for quantitative assays was clearly illustrated. International reference standards are available for cytokines but not for soluble cytokine receptors or soluble activation markers. Marker levels in serum or in plasma were similar except those for IFN-gamma. Most of the analytes were stable under several storage conditions. Thus, batch testing of frozen stored samples is feasible. The findings indicate that for longitudinal studies, the levels of cytokines and immune activation markers in plasma or serum should be measured by using preverified reagents from one manufacturer. The quality of laboratory performance can have an impact on clinical relevance. Proficiency testing and external quality assurance programs can help to develop the needed consensus.