Immunophenotyping Of Whole Blood Research Articles

Abstract A099: Preliminary pharmacodynamic characterization in patients with platinum-resistant ovarian cancer treated with nemvaleukin in combination with pembrolizumab

Abstract A099: Preliminary pharmacodynamic characterization in patients with platinum-resistant ovarian cancer treated with nemvaleukin in combination with pembrolizumab

Translational potential of JAX humanized APOE mice: Peripheral biomarkers of pathology

AbstractBackgroundAlzheimer’s Disease (AD) drives the global rising incidence of neurodegenerative dementia. Disease progression includes cerebral aggregation of amyloid‐beta plaques and immune activation. Many AD animal models carry mutations that cause an early onset of these phenotypes, but the mutations are rare in human populations; most cases are idiopathic and late‐onset AD (LOAD). Another approach utilizing a transgenic APOE animal model may better model clinical populations. APOE4 is the predominant genetic risk factor for LOAD and confers increasing risk for LOAD in allelic fashion, relative to normative APOE3. This study investigates the JAX humanized APOE knock‐in mouse model of LOAD’s translational potential for peripheral biomarkers of pathology in aged, male and female mice.MethodAged mice of both sexes (23‐25 months old; 39M/37F) with APOE3/3,APOE3/4, andAPOE4/4 genotypes underwent blood plasma amyloid‐beta (Aß) measurement. A subset of these animals (30M/28F) additionally received peripheral immunophenotyping of whole blood via flow cytometry. Two‐way ANOVA and post‐hoc t‐tests were conducted to determine data significance.ResultsFemale mice had lower Aß42 plasma levels as well as a decreased Aß42/40 ratio, suggesting higher levels of the aggregate‐prone Aß42 protein in the brain, but there were no observed APOE genotype effects. Blood plasma Aß40 levels did not differ by genotype or sex. Whole blood flow cytometry showed an elevation in CD8+ memory T cells in APOE4/4 mice relative to APOE3/3 andAPOE3/4 mice. Aged female mice had a peripheral immune cell profile consistent with a more reactive and dysfunctional immune system than genotype‐matched aged males: higher levels of CD11b+ B cells, CD4+ helper T cells, and CD8+ cytotoxic T cells along with a lower percentage of naïve CD4+ and CD8+ T cells.ConclusionIn mice aged to resemble a ∼70‐year‐old human population, these results suggest increased brain levels of the aggregate‐prone Aß42 isoform and a reactive peripheral immune system in female APOE mice. This sex difference is consistent with the increased prevalence of LOAD in women. However, the specificity of APOE4 genotype effects may define the translational potential of this humanized APOE mouse model of late‐onset Alzheimer’s Disease.Research supported by T32AG061897, R01AG057931, and RF1AG059093 to RDB.

Severe COVID-19 is characterised by inflammation and immature myeloid cells early in disease progression

SARS-CoV-2 infection causes a wide spectrum of disease severity. Identifying the immunological characteristics of severe disease and the risk factors for their development are important in the management of COVID-19. This study aimed to identify and rank clinical and immunological features associated with progression to severe COVID-19 in order to investigate an immunological signature of severe disease. One hundred and eight patients with positive SARS-CoV-2 PCR were recruited. Routine clinical and laboratory markers were measured, as well as myeloid and lymphoid whole-blood immunophenotyping and measurement of the pro-inflammatory cytokines IL-6 and soluble CD25. All analysis was carried out in a routine hospital diagnostic laboratory. Univariate analysis demonstrated that severe disease was most strongly associated with elevated CRP and IL-6, loss of DLA-DR expression on monocytes and CD10 expression on neutrophils. Unbiased machine learning demonstrated that these four features were strongly associated with severe disease, with an average prediction score for severe disease of 0.925. These results demonstrate that these four markers could be used to identify patients developing severe COVID-19 and allow timely delivery of therapeutics.

Influence of Aerosol Delivered BCG Vaccination on Immunological and Disease Parameters Following SARS-CoV-2 Challenge in Rhesus Macaques.

The tuberculosis vaccine, Bacille Calmette-Guerin (BCG), also affords protection against non-tuberculous diseases attributable to heterologous immune mechanisms such as trained innate immunity, activation of non-conventional T-cells, and cross-reactive adaptive immunity. Aerosol vaccine delivery can target immune responses toward the primary site of infection for a respiratory pathogen. Therefore, we hypothesised that aerosol delivery of BCG would enhance cross-protective action against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and be a deployable intervention against coronavirus disease 2019 (COVID-19). Immune parameters were monitored in vaccinated and unvaccinated rhesus macaques for 28 days following aerosol BCG vaccination. High-dose SARS-CoV-2 challenge was applied by intranasal and intrabronchial instillation and animals culled 6–8 days later for assessment of viral, disease, and immunological parameters. Mycobacteria-specific cell-mediated immune responses were detected following aerosol BCG vaccination, but SARS-CoV-2-specific cellular- and antibody-mediated immunity was only measured following challenge. Early secretion of cytokine and chemokine markers associated with the innate cellular and adaptive antiviral immune response was detected following SARS-CoV-2 challenge in vaccinated animals, at concentrations that exceeded titres measured in unvaccinated macaques. Classical CD14+ monocytes and Vδ2 γδ T-cells quantified by whole-blood immunophenotyping increased rapidly in vaccinated animals following SARS-CoV-2 challenge, indicating a priming of innate immune cells and non-conventional T-cell populations. However, viral RNA quantified in nasal and pharyngeal swabs, bronchoalveolar lavage (BAL), and tissue samples collected at necropsy was equivalent in vaccinated and unvaccinated animals, and in-life CT imaging and histopathology scoring applied to pulmonary tissue sections indicated that the disease induced by SARS-CoV-2 challenge was comparable between vaccinated and unvaccinated groups. Hence, aerosol BCG vaccination did not induce, or enhance the induction of, SARS-CoV-2 cross-reactive adaptive cellular or humoral immunity, although an influence of BCG vaccination on the subsequent immune response to SARS-CoV-2 challenge was apparent in immune signatures indicative of trained innate immune mechanisms and primed unconventional T-cell populations. Nevertheless, aerosol BCG vaccination did not enhance the initial clearance of virus, nor reduce the occurrence of early disease pathology after high dose SARS-CoV-2 challenge. However, the heterologous immune mechanisms primed by BCG vaccination could contribute to the moderation of COVID-19 disease severity in more susceptible species following natural infection.

High CD4-to-CD8 ratio identifies an at-risk population susceptible to lethal COVID-19.

Around half of people with severe COVID‐19 requiring intensive care unit (ICU) treatment will survive, but it is unclear how the immune response to SARS‐CoV‐2 differs between ICU patients that recover and those that do not. We conducted whole‐blood immunophenotyping of COVID‐19 patients upon admission to ICU and during their treatment and uncovered marked differences in their circulating immune cell subsets. At admission, patients who later succumbed to COVID‐19 had significantly lower frequencies of all memory CD8+ T cell subsets, resulting in increased CD4‐to‐CD8 T cell and neutrophil‐to‐CD8 T cell ratios. ROC and Kaplan‐Meier analyses demonstrated that both CD4‐to‐CD8 and neutrophil‐to‐CD8 ratios at admission were strong predictors of in‐ICU mortality. Therefore, we propose the use of the CD4‐to‐CD8 T cell ratio as a marker for the early identification of those individuals likely to require enhanced monitoring and/or pro‐active intervention in ICU.

Clinical and Immunological Metrics During Pediatric Rhesus Macaque Development.

Background: Clinical measurements commonly used to evaluate overall health of laboratory animals including complete blood count, serum chemistry, weight, and immunophenotyping, differ with respect to age, development, and environment. This report provides comprehensive clinical and immunological reference ranges for pediatric rhesus macaques over the first year of life.Methods: We collected and analyzed blood samples from 151 healthy rhesus macaques, aged 0–55 weeks, and compared mother-reared infants to two categories of nursery-reared infants; those on an active research protocol and those under derivation for the expanded specific-pathogen-free breeding colony. Hematology was performed on EDTA-anticoagulated blood using a Sysmex XT2000i, and serum clinical chemistry was performed using the Beckman AU480 chemistry analyzer. Immunophenotyping of whole blood was performed with immunofluorescence staining and subsequent flow cytometric analysis on a BD LSRFortessa. Plasma cytokine analysis was performed using a Millipore multiplex Luminex assay.Results: For hematological and chemistry measurements, pediatric reference ranges deviate largely from adults. Comparison of mother-reared and nursery-reared animals revealed that large differences depend on rearing conditions and diet. Significant differences found between two nursery-reared cohorts (research and colony animals) indicate large influences of experimental factors and anesthetic events on these parameters. Immune cells and cytokine responses presented with distinct patterns for infants depending on age, birth location, and rearing conditions.Conclusions: Our results illustrate how the immune system changed over time and that there was variability among pediatric age groups. Reference ranges of results reported here will support interpretations for how infection and treatment may skew common immune correlates used for assessment of pathology or protection in research studies as well as help veterinarians in the clinical care of infant non-human primates. We highlighted the importance of using age-specific reference comparisons for pediatric studies and reiterated the utility of rhesus macaques as a model for human studies. Given the rapid transformation that occurs in multiple tissue compartments after birth and cumulative exposures to antigens as individuals grow, a better understanding of immunological development and how this relates to timing of infection or vaccination will support optimal experimental designs for developing vaccines and treatment interventions.

1124P - Single cycle induction treatment with cisplatin/docetaxel plus durvalumab/tremelimumab in stage III-IVB head and neck squamous cell cancer (CheckRad-CD8 trial)

BackgroundIn head and neck squamous cell cancer (HNSCC) a valid predictive parameter for the efficacy of immune-checkpoint inhibitors is still missing especially in locally advanced stages. MethodsIn the phase II CheckRad-CD8 trial unselected patients with HNSCC stage III-IVB receive one cycle of induction chemo-immunotherapy with cisplatin (30mg/m² d1-3)/ docetaxel (75mg/m² d1) plus durvalumab (1500mg absolute d5)/ tremelimumab(75mg absolute d5). Intra- and peritumoral CD8+ cytotoxic T-cells are assessed before and after the induction chemo-immunotherapy. Patients with CD8+ T-cell increase after induction chemo-immunotherapy enter radio-immunotherapy, patients without CD8+ T-cell increase enter radio-chemotherapy. This interim analysis including immunophenotyping of whole blood was performed after 10 patients had completed the re-evaluation after induction chemo-immunotherapy. Results6 patients with oropharyngeal, 2 patients with hypopharyngeal and 2 patients with supraglottic laryngeal cancer were included. The mean pre-treatment intratumoral CD8 density was 1094 CD8+ cells/mm². 8 of 10 patients had a pathological complete response of their primary tumor defined by complete absence of remaining tumor cells in re-biopsies after induction treatment. The other two patients showed an average intratumoral increase from 227 CD8+ cells/mm² to 1074 CD8+ cells/mm². According to RECIST 1.1 criteria 6 patients had a partial response (PR), 3 patients a stable disease (SD), 1 patient was not evaluable. Grade III-IV toxicity included one case of hepatitis and one infectious diarrhea. Detailed immunophenotyping revealed a trend of slight reduction of CD8+ T-cells in the peripheral blood of patients with initially lower numbers of intratumoral CD8+ T-cells. The early activation marker CD69 is increased on T-cells and PD-1 on T-helper cells after induction treatment. ConclusionsThese preliminary results suggest a promising response to single cycle induction treatment with cisplatin/ docetaxel plus durvalumab/ tremelimumab in unselected HNSCC patients. Furthermore, they show an induction of an immune response in both in the tumor tissue and the peripheral blood. Clinical trial identificationNCT03426657. Legal entity responsible for the studyThe authors. FundingAstraZeneca. DisclosureM. Hecht: Research grant / Funding (institution): AstraZeneca; Advisory / Consultancy, Research grant / Funding (institution), Travel / Accommodation / Expenses: MSD. A. Gostian: Advisory / Consultancy: test. M. Eckstein: Honoraria (self), Advisory / Consultancy: AstraZeneca; Advisory / Consultancy, Research grant / Funding (institution): Janssen-Cilag/Johnson&Johnson; Honoraria (self): Astellas; Honoraria (self): Roche. M.G. Hautmann: Honoraria (self): AstraZeneca. S. Laban: Honoraria (self), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy: BMS; Honoraria (self), Advisory / Consultancy: AstraZeneca; Honoraria (self): Merck Serono. A. Hartmann: Honoraria (self), Advisory / Consultancy: BMS; Honoraria (self), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Roche; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Cepheid; Honoraria (self), Advisory / Consultancy: AstraZeneca; Honoraria (self), Advisory / Consultancy: Boehringer Ingelheim; Honoraria (self), Advisory / Consultancy: AbbVie; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Janssen; Advisory / Consultancy, Research grant / Funding (institution): NanoString; Advisory / Consultancy, Research grant / Funding (institution): Illumina; Advisory / Consultancy: Quiagen; Advisory / Consultancy, Research grant / Funding (institution): Biontech; Advisory / Consultancy: 3D Histotech. U. Gaipl: Research grant / Funding (institution): AstraZeneca; Research grant / Funding (institution): MSD. R. Fietkau: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Merck Serono; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Novocure; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Brainlab; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Fresenius Kabi; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): BMS; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): MSD. All other authors have declared no conflicts of interest.

1161P - Intratumoral and peripheral exploratory biomarker analysis in patients with locoregional, recurrent head and neck squamous cell carcinoma (rHNSCC) treated with RM-1929 photoimmunotherapy

BackgroundPhotoimmunotherapy (PIT) is a platform technology that utilizes a photoactivatable dye conjugated to a cancer-targeting antibody. RM-1929 is composed of anti-EGFR antibody cetuximab and IRDye® 700DX. Binding of RM-1929 to EGFR followed by tumor illumination with non-thermal red light elicits rapid necrosis of EGFR-expressing cancer cells. RM-1929 PIT treatment was evaluated in a Phase 1/2a trial in patients with rHNSCC who failed multiple standard of care therapies, and demonstrated a favorable safety profile and resulted in positive response rates (Cognetti et al. ASCO 2019). Here we report preliminary data from exploratory biomarker studies from this study. MethodsPhase 1 included 9 patients and Phase 2a cohort 30 patients. Pre-treatment biopsies and blood were collected within 12 months and 2 weeks prior to treatment, respectively. Post-treatment biopsies and blood samples were collected after cycle 1 and multiple time points during treatment cycles, respectively. EGFR and PD-L1 IHC expression and plasma cytokines levels were measured. PBMCs were phenotyped using innate and adaptive immune-marker panels. ResultsIn 25 patients with pre-treatment biopsies, no trend was observed between EGFR expression and best target tumour response. In 12 patients for which pre- and post-treatment biopsies were available, EGFR expression was maintained in residual tumour after RM-1929 PIT treatment. Additionally, treatment was associated with induction of PD-L1 expression in tumour and immune cells in 10 out of 12 cases. In 13 samples tested, elevated baseline plasma cytokine levels were observed in 4 of 7 responders (3 of 4 CR and 1 of 3 PR) and 1 of 6 non-responders (1 of 5 SD and 0 of 1 PD). Immunophenotyping of whole blood showed systemic induction of innate and adaptive immunity (e.g. NK cells, cytokines, lymphocytes, monocytes, CD4 and CD8 T-cells) after treatment in 15 of 18 patients. ConclusionsBiomarker analysis in this limited data set provided evidence of potential activation of innate and adaptive immunity following RM-1929 PIT treatment. Further evaluation of these biomarkers will be conducted in a Phase 3 trial (NCT03769506). Clinical trial identificationNCT02422979. Legal entity responsible for the studyRakuten Medical, Inc. FundingRakuten Medical, Inc. DisclosureJ.D. Bui: Advisory / Consultancy: Rakuten Medical, Inc.; Advisory / Consultancy, Research grant / Funding (self): Ignyta, Inc.; Shareholder / Stockholder / Stock options: Paramita Therapeutics. N. Suslov: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. D. Yadav: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. J. Fong: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. E. Sun: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. M. Haedo: Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc. M. Garcia-Guzman: Leadership role, Shareholder / Stockholder / Stock options, Full / Part-time employment: Rakuten Medical, Inc.

Standardized Whole-Blood Immunophenotyping Panels on Flow Cytometry for Transplant Recipients and Clinical Trials

Standardized Whole-Blood Immunophenotyping Panels on Flow Cytometry for Transplant Recipients and Clinical Trials

An efficient human whole blood workflow using CyTOF technology: a lyophilized 30-plex antibody panel coupled with automated data analysis

Abstract CyTOF® mass cytometry is a highly multiplexed, single-cell analysis platform that uses metal-tagged antibodies. A significant advantage of this technology is its ability to resolve more than 30 markers in a single panel without the need for compensation. Nonetheless, a highly multiplexed panel requires optimization of antibody titers, full panel verification, sample preparation, data acquisition, and analysis. Preparation of a staining cocktail from 30 individual tubes may be prone to errors. Not only is data analysis time-consuming for complex panels, it is difficult to interpret without expertise in immunology. We have developed a lyophilized 30-plex immunphenotyping panel contained in a single tube, an efficient workflow, and an automated software solution for human whole blood analysis using mass cytometry. The panel focuses on T cell lineage while also capturing other relevant immune populations. Blood is added directly to the lyophilized antibody tube, followed by RBC lysis, wash, and fixation steps and finally data acquisition of stained samples on the Helios™ system. The dedicated software tool accepts FCS3.0 files and in under 10 minutes automatically generates reports on the number of live cells, percentage of specific cell populations, staining intensities, histograms, 2D dot plots, and tSNE graphs. The auto-calculated frequencies of populations are comparable to manual gating, with a validated correlation coefficient over 0.9. The panel and software tool enable researchers to streamline immunophenotyping of whole blood while accurately and reproducibly monitoring changes in immune cell subsets in patient samples.

Cryopreservation of human whole blood allows immunophenotyping by flow cytometry up to 30 days after cell isolation

Immunophenotyping of whole blood (WB) by flow cytometry (FC) is used clinically to assess a patient's immune status and also in biomedical research. Current protocols recommend storage of immunolabeled samples at 4°C with FC analysis to be completed within seven days. This data acquisition window can be extended to up to one year post-labeling, but this requires cryopreservation of the samples at ultra-low temperatures (≤−80°C or in liquid nitrogen). In this study we optimized a standardized cryopreservation protocol to enable preservation of immunolabeled, human WB samples at −20°C for FC and tested its effectiveness after 0, 5, 15 or 30days. Analysis of stored samples shows that this protocol effectively preserves immunolabeled WB samples and that the duration of storage has no effect on morphology, viability or frequency of WB cell subpopulations, and that the intensity of fluorescent signal from labeled extracellular markers is fully preserved for at least 15days, and up to 30days for some markers. We demonstrate that using this protocol, we are able to differentiate resting versus activated WB cells as demonstrated by detection of significantly increased expression of CD11b by myeloid cells in WB samples pretreated with LPS (100μg/mL for 12h). Finally, we show that this method allows for labeling and detection of the intracellular cytokine (IL-8) up to 30days following cryopreservation from myeloid cells, in previously labeled and cryopreserved WB samples.

Immunomodulatory and toxicological safety studies of two novel anti-leishmanial compounds

Background: Leishmaniasis is a parasitic disease which can manifest in various clinical forms and the visceral form is highly fatal if not treated. The drugs available are either highly costly or have poor efficacy against the parasite. Hence there is a need to find new molecules and compounds for the treatment of this disease. However, to put the new compounds in clinical trials, their toxicity and immune-modulatory effects must be ascertained to avoid harmful effects on the host. Methods & Materials: Putative immunomodulatory activity of two advanced preclinical anti-kinetoplastid candidates (KIND0001589 and KIND0001591) was evaluated, using primary human peripheral blood cells from healthy controls and kala-azar patients. Amphotericin B was used as standard drug control. The optimal concentrations of KIND0001589 (0.0134 μg/mL) and KIND0001591 (0.03 μg/mL) was used, to pre-treat the peripheral blood mononuclear cell, for 14 hours followed by addition of, PMA (25 ng/mL) and Ionomycin (1 μg/mL) for 4 hours together with Brefeldin A (1 μg/mL). Cell viability was assessed by determining the frequency of Annexin V/7AAD positive cells in CD3+, CD14+ and CD19+ leukocyte subpopulations through BD Influx FACS system. Immunophenotyping was determined in CD3+, CD4+ and CD3+, CD8+ T cells, CD14+ monocytes and CD19+ B cells. The frequency of T-cells, monocytes and B-cells expressing IFNγ, and TNF-α, respectively, was determined by the same flow cytometer. Results: Short term ex-vivo immunophenotyping assay showed KIND001589 induces CD4+TNF-α and CD4+IFNγ including IL-4, IL-10 and IL-17, in all patients. Where as KIND0001591 induced a short term immunostimulation of CD8+ T cells. Both KIND000189 and KIND0001591 highly induced CD14+ monocytes (CD14+IFNγ and CD14+TNF-α) as compared to the standard drug. KIND0001589 does not induce any B cells mediated immuno-stimulation where as KIND0001591 induced immuno-stimulation in one Patient. KIND0001589 showed stronger short term immunomodulatory activity than KIND0001591. Conclusion: Both the novel compounds (KIND0001589 and KIND0001589) were found to be safe and potential anti-kinetoplastids for animal and human trials. Funding: The study was funded from the European Community's Seventh Framework Program under the grant agreement 602773 (Project KINDReD). Immunophenotyping of whole blood from kala-azar Patient 1 Immunophenotyping of whole blood from kala-azar Patient 2 Immunophenotyping of whole blood from kala-azar Patient 3

Disease Remission in a Horse with EHV‐5‐Associated Lymphoma

Disease Remission in a Horse with <scp>EHV</scp>‐5‐Associated Lymphoma

Regulatory T Cells Phenotype in Different Clinical Forms of Chagas' Disease

CD25High CD4+ regulatory T cells (Treg cells) have been described as key players in immune regulation, preventing infection-induced immune pathology and limiting collateral tissue damage caused by vigorous anti-parasite immune response. In this review, we summarize data obtained by the investigation of Treg cells in different clinical forms of Chagas' disease. Ex vivo immunophenotyping of whole blood, as well as after stimulation with Trypanosoma cruzi antigens, demonstrated that individuals in the indeterminate (IND) clinical form of the disease have a higher frequency of Treg cells, suggesting that an expansion of those cells could be beneficial, possibly by limiting strong cytotoxic activity and tissue damage. Additional analysis demonstrated an activated status of Treg cells based on low expression of CD62L and high expression of CD40L, CD69, and CD54 by cells from all chagasic patients after T. cruzi antigenic stimulation. Moreover, there was an increase in the frequency of the population of Foxp3+ CD25HighCD4+ cells that was also IL-10+ in the IND group, whereas in the cardiac (CARD) group, there was an increase in the percentage of Foxp3+ CD25High CD4+ cells that expressed CTLA-4. These data suggest that IL-10 produced by Treg cells is effective in controlling disease development in IND patients. However, in CARD patients, the same regulatory mechanism, mediated by IL-10 and CTLA-4 expression is unlikely to be sufficient to control the progression of the disease. These data suggest that Treg cells may play an important role in controlling the immune response in Chagas' disease and the balance between regulatory and effector T cells may be important for the progression and development of the disease. Additional detailed analysis of the mechanisms on how these cells are activated and exert their function will certainly give insights for the rational design of procedure to achieve the appropriate balance between protection and pathology during parasite infections.

Chronic Epstein-Barr virus-related hepatitis in immunocompetent patients

To investigate reactivated Epstein-Barr virus (EBV) infection as a cause for chronic hepatitis. Patients with occasionally established elevated serum aminotransferases were studied. HIV, HBV and HCV-infections were excluded as well as any other immunosuppressive factors, metabolic or toxic disorders. EBV viral capsid antigen (VCA) IgG and IgM, EA-R and EA-D IgG and Epstein-Barr nuclear antigen (EBNA) were measured using IFA kits. Immunophenotyping of whole blood was performed by multicolor flow cytometry. CD8(+) T cell responses to EBV and PHA were determined according to the intracellular expression of IFN-gamma. The mean alanine aminotransferase (ALT) and gamma glutamyl transpeptidase (GGTP) values exceeded twice the upper normal limit, AST/ALT ratio < 1. Serology tests showed reactivated EBV infection in all patients. Absolute number and percentages of T, B and NK cells were within the reference ranges. Fine subset analysis, in comparison to EBV(+) healthy carriers, revealed a significant decrease of naive T cells (P < 0.001), accompanied by increased percentage of CD45RA(-) (P < 0.0001), and terminally differentiated CD28(-)CD27(-)CD8(+) T cells (P < 0.01). Moderately elevated numbers of CD38 molecules on CD8(+) T cells (P < 0.05) proposed a low viral burden. A significantly increased percentage of CD8(+) T cells expressing IFN-gamma in response to EBV and PHA stimulation was registered in patients, as compared to controls (P < 0.05). Liver biopsy specimens from 5 patients revealed nonspecific features of low-grade hepatitis. Chronic hepatitis might be a manifestation of chronic EBV infection in the lack of detectable immune deficiency; the expansion of CD28(-)CD27(-) and increase of functional EBV-specific CD8(+) T cells being the only surrogate markers of viral activity.

Chagasic Patients with Indeterminate Clinical Form of the Disease have High Frequencies of Circulating CD3+CD16–CD56+ Natural Killer T Cells and CD4+CD25High Regulatory T Lymphocytes

Several studies have demonstrated that different clinical manifestations of human Chagas' disease are associated with distinct and complex host-parasite relationships directly involving the immune system. In this context, it has been proposed that tissue damage might be more severe in the absence of regulatory mechanisms that involve both innate and adaptive immune responses. Herein, we describe a descriptive phenotypic profile focusing on the frequency of major regulatory T cells [CD4+CD25high and natural killer T (NKT) lymphocytes] in different clinical forms of Chagas' disease. Ex vivo immunophenotyping of whole blood demonstrated that the indeterminate clinical form displays a higher frequency of both CD4+CD25high and NKT regulatory cells (CD3+CD16-CD56+), associated with increased levels of circulating cytotoxic NK cells (CD3-CD16+CD56+ and CD3-CD16+CD56dim NK cells). By contrast, the increased percentage of activated CD8+HLA-DR+ T-cell subset was exclusively associated with severe clinical forms of Chagas' disease. We hypothesize that regulatory T cells may be able to control the deleterious cytotoxic activity in the indeterminate clinical form by inhibiting the activation of CD8+HLA-DR+ T cells. The lack of regulated populations in cardiac and digestive clinical forms could account for impaired immune response that culminates in strong cytotoxic activity and tissue damage.

Fixation and cryopreservation of whole blood and isolated mononuclear cells: Influence of different procedures on lymphocyte subset analysis by flow cytometry

Immunophenotyping of whole blood (WB) and isolated peripheral blood mononuclear cells (PBMCs) is a common tool used to evaluate immune system changes in clinical studies. The development of methods that would allow preservation of samples for flow cytometric analysis is important for the extension of this technology to field testing in settings where the equipment might be not readily accessible. Three-color flow cytometric analysis was used to determine percentages of T cells and their subsets (CD3(+), CD4(+), CD8(+)), B cells (CD19(+)), and natural killer cells (CD16(+)/56(+)) in WB and PBMCs using variations of a standard stain/fix WB staining procedure (Optilyse) that included staining following fixation and freezing of fixed samples before or after staining. Comparable lymphocyte subset percentages in WB or PBMCs were observed regardless of Optliyse method used (all Ps >/= 0.8). However, differences in fluorescence intensity for several markers were observed across procedures. Compared with the standard stain/fix procedures, fix/stain decreased the mean fluorescence intensities for CD4, CD8, CD19 and CD16/56 in WB and PBMCs (P </= 0.03 for these markers P = 0.105 for CD8 in PBMCs). Further decreases in mean fluorescence intensity were seen with the fix/stain/freeze procedure. The stain/fix/freeze yielded intensities largely comparable to those seen with standard stain/fix procedure (P >/= 0.13), suggesting that, when the markers of interest are known at the time of field collection, implementation of this procedure might be desirable. Fix/freeze/stain resulted in diminution of intensity in general, but they tended to be more modest than those seen for fix/stain/freeze and therefore might be applicable to field studies in instances when the specific markers of interest cannot be defined upfront. Freezing of fixed WB and PBMCs before or after cell surface staining is a reliable method for preserving specimens in field sites for later determination of lymphocyte subset percentages, which are commonly assessed in immunodeficient and cancer patients.

Long-term effects of intermittent interleukin 2 therapy in patients with HIV infection: characterization of a novel subset of CD4+/CD25+ T cells

AbstractThe long-term immunologic effects of intermittent interleukin 2 (IL-2) therapy were evaluated in a cross-sectional study by comparing 3 groups: HIV-seronegative volunteers, HIV-infected (HIV+) patients receiving highly active antiretroviral therapy (HAART), and HIV+ patients receiving HAART and intermittent IL-2. Whole-blood immunophenotyping was performed to study expression of the IL-2 receptor chains on T lymphocytes and natural killer cells and to further characterize CD4+/CD25+ T cells. Increased CD25 expression, especially in CD4+ T cells but also in CD8+ T cells, without increases in expression of the β and γ chains of the IL-2 receptor was detected in the IL-2 group. Up to 79% of naive CD4+ T cells (median, 61%) from patients in the IL-2 group expressed CD25, and the number of naive CD4+/CD25+ T cells correlated positively with both the total and naive CD4+ T-cell counts. A discrete population of CD45 double intermediate RA+/RO+CD4+ cells was also preferentially expanded in the IL-2 group, and the number of these cells strongly correlated with the total CD4+ count. Despite increases in CD25 expression, T lymphocytes from patients treated with IL-2 did not have increased expression of early (CD69) or late (CD95) activation markers or evidence of recent proliferation (Ki67). Both CD4+/CD25+ and CD4+/CD25− cells from IL-2–treated HIV+ patients proliferated in response to mitogens, specific antigens, and T-cell-receptor–mediated stimuli. Thus, intermittent administration of IL-2 in HIV+ patients leads to preferential expansion of a unique subset of CD4+ T cells that may represent a critical population in T-cell homeostasis.

Long-term effects of intermittent interleukin 2 therapy in patients with HIV infection: characterization of a novel subset of CD4+/CD25+ T cells

The long-term immunologic effects of intermittent interleukin 2 (IL-2) therapy were evaluated in a cross-sectional study by comparing 3 groups: HIV-seronegative volunteers, HIV-infected (HIV+) patients receiving highly active antiretroviral therapy (HAART), and HIV+ patients receiving HAART and intermittent IL-2. Whole-blood immunophenotyping was performed to study expression of the IL-2 receptor chains on T lymphocytes and natural killer cells and to further characterize CD4+/CD25+ T cells. Increased CD25 expression, especially in CD4+ T cells but also in CD8+ T cells, without increases in expression of the β and γ chains of the IL-2 receptor was detected in the IL-2 group. Up to 79% of naive CD4+ T cells (median, 61%) from patients in the IL-2 group expressed CD25, and the number of naive CD4+/CD25+ T cells correlated positively with both the total and naive CD4+ T-cell counts. A discrete population of CD45 double intermediate RA+/RO+CD4+ cells was also preferentially expanded in the IL-2 group, and the number of these cells strongly correlated with the total CD4+ count. Despite increases in CD25 expression, T lymphocytes from patients treated with IL-2 did not have increased expression of early (CD69) or late (CD95) activation markers or evidence of recent proliferation (Ki67). Both CD4+/CD25+ and CD4+/CD25− cells from IL-2–treated HIV+ patients proliferated in response to mitogens, specific antigens, and T-cell-receptor–mediated stimuli. Thus, intermittent administration of IL-2 in HIV+ patients leads to preferential expansion of a unique subset of CD4+ T cells that may represent a critical population in T-cell homeostasis.

Peripheral Blood Mononuclear Phagocyte Subpopulations as Cellular Markers in Hypercholesterolemia

Mononuclear phagocytes play a major role in the development of vascular lesions in atherogenesis. The goal of our study was to characterize circulating blood monocyte subpopulations as potential cellular markers of systemic immunological abnormalities in hypercholesterolemia. In normal subjects, three-parameter immunophenotyping of whole blood revealed that 61.3 +/- 6.0% of monocytes showed "bright" expression of the lipopolysaccharide receptor (LPSR: CD14) and Fc gamma receptor I (RI: CD64) without expression of Fc gamma-RIII (CD16). Other monocyte subsets (populations 2, 3, 4, and 5) were characterized by the simultaneous expression of both Fc gamma-R's (25.6 +/- 5.0%), isolated expression of Fc gamma-RIII (9.4 +/- 1.7%), or high expression of CD33 (3.7 +/- 1.1%) with only dim expression of CD14, respectively. The smallest subset of monocytes (population 5: 2.1 +/- 0.8%) differed from the predominant population of CD14brightCD64+CD16- monocytes by additional expression of neural cell adhesion molecule (N-CAM: CD56). In a group of hypercholesterolemic patients (n = 19), high density lipoprotein cholesterol levels were negatively correlated to the population size of CD64-CD16+ monocytes. In both healthy subjects (n = 55) and hypercholesterolemic patients, the rare apolipoprotein E3/E4 and E4/E4 phenotypes were associated with a tendency toward a larger population of CD64-CD16+ monocytes. Expression of the variant activation antigen CD45RA by peripheral blood mononuclear phagocytes showed a positive correlation to plasma levels of the atherogenic lipoproteins low density lipoprotein and lipoprotein(a). These data suggest that systemic abnormalities in mononuclear phagocyte subpopulations may play a role in the pathogenesis of atherosclerosis.