T cell responses in fresh and cryopreserved peripheral blood mononuclear cells: Kinetics of cell viability, cellular subsets, proliferation, and cytokine production

Technical pitfalls when collecting, cryopreserving, thawing, and stimulating human T-cells

The collection, cryopreservation, thawing, and culture of peripheral blood mononuclear cells (PBMCs) can profoundly influence T cell viability and immunogenicity. Gold-standard PBMC processing protocols have been developed by the Office of HIV/AIDS Network Coordination (HANC); however, these protocols are not universally observed. Herein, we have explored the current literature assessing how technical variation during PBMC processing can influence cellular viability and T cell immunogenicity, noting inconsistent findings between many of these studies. Amid the mounting concerns over scientific replicability, there is growing acknowledgement that improved methodological rigour and transparent reporting is required to facilitate independent reproducibility. This review highlights that in human T cell studies, this entails adopting stringent standardised operating procedures (SOPs) for PBMC processing. We specifically propose the use of HANC's Cross-Network PBMC Processing SOP, when collecting and cryopreserving PBMCs, and the HANC member network International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) PBMC Thawing SOP when thawing PBMCs. These stringent and detailed protocols include comprehensive reporting procedures to document unavoidable technical variations, such as delayed processing times. Additionally, we make further standardisation and reporting recommendations to minimise and document variability during this critical experimental period. This review provides a detailed overview of the challenges inherent to a procedure often considered routine, highlighting the importance of carefully considering each aspect of SOPs for PBMC collection, cryopreservation, thawing, and culture to ensure accurate interpretation and comparison between studies.

A whole blood intracellular cytokine assay optimised for field site studies demonstrates polyfunctionality of CD4+ T cells in acute scrub typhus

BACKGROUND

Assessment of cellular immune responses by combining intracellular cytokine staining and immunophenotyping using flow cytometry enables the simultaneous measurement of T cell phenotype and effector function in response to pathogens and vaccines. The use of whole blood samples rather than peripheral blood mononuclear cells avoids both the need for immediate processing and loss of functional antigen presenting cells due to processing and cryopreservation. Using whole blood provides the possibility to stimulate peripheral T cells in situ, and is more suitable for studies where sample volume is limited, such as those involving children, the elderly and critically ill patients. The aim of this study was to provide a robust tool for the assessment of antigen-specific T cell responses in a field site setting with limited resources.

METHODOLOGY/PRINCIPLE FINDINGS

We optimised a flow cytometry-based whole blood intracellular cytokine assay (WBA) with respect to duration of antigen stimulation and intracellular protein retention time. We demonstrate the ability of the WBA to capture polyfunctional T cell responses in the context of acute scrub typhus infection, by measuring IFN-γ, TNF and IL-2 in CD4+ and CD8+ T cells in response to the causative agent O. tsutsugamushi (OT). Using an optimised OT antigen preparation, we demonstrate the presence of polyfunctional antigen-specific memory CD4+ T cells in the blood of scrub typhus patients.

CONCLUSIONS/SIGNIFICANCE

In conclusion, this flow cytometry-based WBA is well-suited for use at field study sites, and enables the assessment of polyfunctional T cell responses to infectious agents and vaccines through delineation of antigen-specific cytokine secretion at the single cell level.

[The influence of fluoxetine on neuroimmune interaction in multiple sclerosis]

OBJECTIVE

To study the effect of fluoxetine on Th17- and Th1-immune response, which plays an important role in the pathogenesis of multiple sclerosis (MS).

MATERIAL AND METHODS

Ten patients with relapsing-remitting MS and ten healthy subjects were examined. The functions of Th17- and Th1-immune responses were assessed by the production of cytokines interleukin-17 (IL-17) and interferon-gamma (IFN-γ) by CD4+ T cells stimulated with macrophages or microbeads coated with anti-CD3 and anti-CD28-antibodies. To assess the effect of fluoxetine on the macrophages-induced Th17- and Th1-immune response, macrophages were pre-incubated in the presence of fluoxetine and co-cultured with autologous CD4+ T-cells. In the case of stimulation of CD4+ T-cells with anti-CD3/CD28-microbeads, fluoxetine was added directly to the T-helper cells before adding of microbeads. In addition, we evaluated the effect of fluoxetine on the production of the factors of differentiation of Th17-cells cytokines IL-6 and IL-1β by macrophages. The levels of cytokines in the cell culture supernatants were measured by ELISA.

RESULTS

The production of IL-17 and IFN-γ by CD4+ T-cells stimulated with macrophages or anti-CD3/CD28-microbeads was comparable between the groups. Fluoxetine suppressed the production of IL-17 and IFN-γ by anti-CD/CD28-stimulated CD4+ T-cells in both groups. Fluoxetine also suppressed the production of IL-6 and IL-1β by macrophages as well as their ability to induce IL-17 and IFN-γ production by CD4+ T-cells in both groups.

CONCLUSIONS

Fluoxetine may have an anti-inflammatory effect in MS that could be mediated by suppression of Th17- and Th1-cells or macrophage-induced Th17- and Th1-immune response.

Circular RNA profile in Graves' disease and potential function of hsa_circ_0090364

Background

Graves' disease is a common autoimmune disease. Cytokines and their signalling pathways play a major part in the pathogenesis of Graves' disease; however, the underlying mechanism needs to be clarified.

Aims

The aim of this study was to explore whether circular RNAs participate in the immunological pathology of Graves' disease via cytokine-related signalling pathways.

Methods

Bioinformatics analysis was performed to identify differentially expressed circular RNAs and their targets and associated pathways. A total of three patients with Graves' disease and three sex- and age-matched healthy controls were enrolled for validation with microarray analysis and real-time quantitative PCR (qPCR). An additional 24 patients with Graves' disease and 24 gender- and age-matched controls were included for validation by real-time fluorescent qPCR. Flow cytometry and CCK8 assays were used to detect the apoptotic and proliferative levels of Jurkat cells (T lymphocytes) with the silenced expression of circRNA. ELISA was performed to detect the growth and apoptosis-related proteins. The competition mechanism of endogenous RNA was explored by real-time fluorescence qPCR.

Results

A total of 366 significantly differentially expressed circular RNAs were identified in the Graves' disease group compared to healthy controls. The level of hsa_circ_0090364 was elevated in Graves' disease patients and positively correlated with thyroid-stimulating hormone receptor antibodies. Further analyses suggested that hsa_circ_0090364 may regulate the JAK-STAT pathway via the hsa-miR-378a-3p/IL-6ST/IL21R axis to promote cell growth.

Conclusions

These results provide novel clues into the pathophysiological mechanisms of Graves' disease and potential targets for drug treatment.

CAR-T manufactured from frozen PBMC yield efficient function with prolonged in vitro production

Chimeric antigen receptor (CAR)-T cells are engineered to identify and eliminate cells expressing a target antigen. Current manufacturing protocols vary between commercial CAR-T cell products warranting an assessment of these methods to determine which approach optimally balances successful manufacturing capacity and product efficacy. One difference between commercial product manufacturing methods is whether T cell engineering begins with fresh (unfrozen) patient cells or cells that have been cryopreserved prior to manufacture. Starting with frozen PBMC material allows for greater manufacturing flexibility, and the possibility of collecting and storing blood from patients prior to multiple lines of therapy. We prospectively analyzed if second generation anti-CD19 CAR-T cells with either CD28 or 4-1BB co-stimulatory domains have different phenotype or function when prepared side-by-side using fresh or cryopreserved PBMCs. We found that cryopreserved PBMC starting material is associated with slower CAR-T cell expansion during manufacture but does not affect phenotype. We also demonstrate that CAR-T cell activation, cytokine production and in vitro anti-tumor cytotoxicity were not different when CAR-T cells were manufactured from fresh or cryopreserved PBMC. As CAR-T cell therapy expands globally, the need for greater flexibility around the timing of manufacture will continue to grow. This study helps support the concept that cryopreservation of PBMCs could be the solution to these issues without compromising the quality of the final CAR-T product.

High-Dimensional Analysis Reveals Distinct Endotypes in Patients With Idiopathic Inflammatory Myopathies

The idiopathic inflammatory myopathies (IIM) are a rare clinically heterogeneous group of conditions affecting the skin, muscle, joint, and lung in various combinations. While myositis specific autoantibodies are well described, we postulate that broader immune endotypes exist in IIM spanning B cell, T cell, and monocyte compartments. This study aims to identify immune endotypes through detailed immunophenotyping of peripheral blood mononuclear cells (PBMCs) in IIM patients compared to healthy controls. We collected PBMCs from 17 patients with a clinical diagnosis of inflammatory myositis and characterized the B, T, and myeloid cell subsets using mass cytometry by time of flight (CyTOF). Data were analyzed using a combination of the dimensionality reduction algorithm t-distributed stochastic neighbor embedding (t-SNE), cluster identification, characterization, and regression (CITRUS), and marker enrichment modeling (MEM); supervised biaxial gating validated populations identified by these methods to be differentially abundant between groups. Using these approaches, we identified shared immunologic features across all IIM patients, despite different clinical features, as well as two distinct immune endotypes. All IIM patients had decreased surface expression of RP105/CD180 on B cells and a reduction in circulating CD3+CXCR3+ subsets relative to healthy controls. One IIM endotype featured CXCR4 upregulation across all cellular compartments. The second endotype was hallmarked by an increased frequency of CD19+CD21loCD11c+ and CD3+CD4+PD1+ subsets. The experimental and analytical methods we describe here are broadly applicable to studying other immune-mediated diseases (e.g., autoimmunity, immunodeficiency) or protective immune responses (e.g., infection, vaccination).

The Dual Role of the β2-Adrenoreceptor in the Modulation of IL-17 and IFN-γ Production by T Cells in Multiple Sclerosis

Norepinephrine is a neurotransmitter that also has an immunomodulatory effect and is involved in multiple sclerosis (MS) pathogenesis. This study aimed to clarify the role of the β₂-adrenoreceptor in the norepinephrine-mediated modulation of interleukin-17 (IL-17) and interferon-γ (IFN-γ) production, which play a critical pathogenetic role in MS. CD4⁺ T cells obtained from twenty-five relapsing-remitting MS patients and sixteen healthy subjects were cultured ex vivo with norepinephrine and/or β₂-adrenoreceptor antagonist or agonist, followed by a cytokine production analysis using ELISA. Norepinephrine suppressed IL-17 and IFN-γ production by the anti-CD3/anti-CD28-microbead-stimulated CD4⁺ T cells in both groups. Blockade of the β₂-adrenoreceptor with the specific antagonist ICI 118.551 enhanced norepinephrine-mediated IL-17 suppression but decreased its inhibitory effect on IFN-γ production in MS patients. In contrast, the β₂-adrenoreceptor agonist formoterol did not influence norepinephrine’s inhibitory effect on cytokine production in both groups. The blockade of the β₂-adrenoreceptor, even in the absence of exogenous norepinephrine, suppressed IL-17 production but did not influence IFN-γ production in both groups. Conversely, β₂-adrenoreceptor activation by formoterol decreased IFN-γ production and did not affect IL-17 production in both groups. These data illustrate the inhibitory effect of norepinephrine on IL-17 and IFN-γ production by CD4⁺ T cells in MS. The inhibitory effect of norepinephrine on IFN-γ production by CD4⁺ T cells in MS could be mediated via β₂-adrenoreceptor activation.

Taraxasterol mitigates Con A-induced hepatitis in mice by suppressing interleukin-2 expression and its signaling in T lymphocytes

Discovery of anti-inflammatory drugs that can suppress T lymphocyte activation and proliferation by inhibiting TCR/CD3 and IL-2/IL-2R signaling is still needed in clinic, though rapamycin and other related reagents have made great success. Taraxasterol (TAS) is an active ingredient of dandelion, an anti-inflammatory medicinal herb with low in vivo toxicity that has long been used in China. Yet the action mechanism of TAS on lymphocytes remains elusive. The anti-inflammatory effects of TAS were evaluated in C57BL/6 mouse primary lymphocytes stimulated with concanavalin A (Con A) in vitro and in mouse model of Con A-induced acute hepatitis in vivo. Our results showed that TAS significantly suppressed Con A-induced acute hepatitis in a mouse model, reducing the hepatic necrosis areas, the release of aminotransferases, and the production of IL-2 and other inflammatory cytokines. Supporting this, in vitro study also showed that TAS reduced the production of IL-2 and the expression of IL-2 receptor subunit α (CD25) upon the stimulation of Con A, which was likely mediated by suppressing NF-κB activation. The downstream pathways of IL-2/IL-2R signaling, including the activation of PI3K/PDK1/mTOR, STAT3 and STAT5, were also suppressed by TAS. Consistently, Con A-induced T cell proliferation was also inhibited by TAS in vitro. Our data indicate that TAS can suppress both T lymphocyte activation and cell proliferation by down-regulating IL-2 expression and its signaling pathway thereby ameliorating Con A-induced acute hepatitis, highlighting TAS as a potential drug candidate for treating inflammatory diseases including autoimmune hepatitis.

T Cell Immune Profiles of Blood and Tumor in Dogs Diagnosed With Malignant Melanoma

Investigation of canine T cell immunophenotypes in canine melanomas as prognostic biomarkers for disease progression or predictive biomarkers for targeted immunotherapeutics remains in preliminary stages. We aimed to examine T cell phenotypes and function in peripheral blood mononuclear cells (PBMC) and baseline tumor samples by flow cytometry, and to compare patient (n = 11–20) T cell phenotypes with healthy controls dogs (n = 10–20). CD3, CD4, CD8, CD25, FoxP3, Ki67, granzyme B, and interferon-γ (IFN-γ) were used to classify T cell subsets in resting and mitogen stimulated PBMCs. In a separate patient cohort (n = 11), T cells were classified using CD3, CD4, CD8, FoxP3, and granzyme B in paired PBMC and single cell suspensions of tumor samples. Analysis of flow cytometric data of individual T cell phenotypes in PBMC revealed specific T cell phenotypes including FoxP3+ and CD25+FoxP3- populations that distinguished patients from healthy controls. Frequencies of IFN-γ+ cells after ConA stimulation identified two different patient phenotypic responses, including a normal/exaggerated IFN-γ response and a lower response suggesting dysfunction. Principle component analysis of selected T cell immunophenotypes also distinguished patients and controls for T cell phenotype and revealed a clustering of patients based on metastasis detected at diagnosis. Findings supported the overall hypothesis that canine melanoma patients display a T cell immunophenotype profile that is unique from healthy pet dogs and will guide future studies designed with larger patient cohorts necessary to further characterize prognostic T cell immunophenotypes.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

The role of 5-HT2B-receptors in fluoxetine-mediated modulation of Th17- and Th1-cells in multiple sclerosis

Fluoxetine is a selective serotonin reuptake inhibitor, which also has an immunomodulatory effect. We investigated the effects of fluoxetine and serotonin (5-HT) on the pro-inflammatory Th17- and Th1-cells in 30 patients with relapsing-remitting MS and 20 healthy subjects. Fluoxetine and 5-HT suppressed IL-17, IFN-γ and GM-CSF production by stimulated СD4⁺ T-cells in both groups. Blockade of 5-HT_2B-receptors decreased the inhibitory effect of fluoxetine on cytokine production in MS patients. Finally, 5-HT_2B-receptor activation inhibits IL-17, IFN-γ and GM-CSF production in both groups. These data suggest an anti-inflammatory role for fluoxetine in MS, which could be mediated by the activation of 5-HT_2B-receptors.

Fresh vs. frozen allogeneic peripheral blood stem cell grafts: A successful timely option

Cryopreservation of grafts has been established in autologous and cord blood transplantation, yet there is little experience regarding the effect of cryopreservation with sibling and unrelated grafts. We evaluated the effect of cryopreservation of grafts on allogeneic transplant outcomes using related, unrelated and haploidentical donors, including 958 patients, age 18-74 years (median 55) and using PBSC for various hematologic malignancies. Fresh grafts were received by 648 (68%) patients, 310 (32%) received cryopreserved. There was no difference between fresh vs cryopreserved grafts for neutrophil engraftment (P = .09), platelet engraftment (P = .11), graft failure (5.6% vs 6.8%, P = .46) and grade II-IV acute graft-vs-host disease (GVHD) (P = .71), moderate/severe chronic GVHD was observed in 176 (27%) vs 123 (40%) patients, respectively (P < .001). Multivariable analysis demonstrated no difference between fresh vs cryopreserved for OS (P = .39) and CIR (P = .08) while fresh grafts demonstrated borderline increased NRM (HR 1.27, 95% CI 1.02-1.59, P = .04). Of note, for patients with no or mild chronic GVHD, CIR was less for fresh compared to cryopreserved (HR = 0.67 for fresh, 95% CI 0.48-0.92, P = .01). We conclude there were no differences in engraftment and survival between fresh and cryopreserved grafts for allogeneic HCT, thus establishing cryopreservation to be a safe option for allogeneic HCT.

The influence of glatiramer acetate on Th17-immune response in multiple sclerosis

Glatiramer acetate (GA) is approved for the treatment of multiple sclerosis (MS). However, the mechanism of action of GA in MS is still unclear. In particular, it is not known whether GA can modulate the pro-inflammatory Th17-type immune response in MS. We investigated the effects of original GA (Copaxone^®, Teva, Israel) and generic GA (Timexone^®, Biocad, Russia) on Th17- and Th1-type cytokine production in vitro in 25 patients with relapsing-remitting MS and 25 healthy subjects. Both original and generic GA at concentrations 50–200 μg/ml dose-dependently inhibited interleukin-17 and interferon-γ production by anti-CD3/anti-CD28-activated peripheral blood mononuclear cells from MS patients and healthy subjects. This effect of GA was reproduced using purified CD4⁺ T cells, suggesting that GA can directly modulate the functions of Th17 and Th1 cells. At high concentrations (100–200 μg/ml), GA also suppressed the production of Th17-differentiation cytokines (interleukin-1β and interleukin-6) by lipopolysaccharide (LPS)-activated dendritic cells (DCs). These GA/LPS-treated DCs induced lower interleukin-17 and interferon-γ production by autologous CD4⁺ T cells compared to LPS-treated DCs. These data suggest that GA can inhibit Th17-immune response and that this inhibitory effect is preferentially exercised by direct influence of GA on T cells. We also demonstrate a comparable ability of original and generic GA to modulate pro-inflammatory cytokine production.

Bispecific anti-CD20, anti-CD19 CAR T cells for relapsed B cell malignancies: a phase 1 dose escalation and expansion trial

Chimeric antigen receptor (CAR) T cells targeting CD19 are a breakthrough treatment for relapsed, refractory B cell malignancies^1-5. Despite impressive outcomes, relapse with CD19^- disease remains a challenge. We address this limitation through a first-in-human trial of bispecific anti-CD20, anti-CD19 (LV20.19) CAR T cells for relapsed, refractory B cell malignancies. Adult patients with B cell non-Hodgkin lymphoma or chronic lymphocytic leukemia were treated on a phase 1 dose escalation and expansion trial (NCT03019055) to evaluate the safety of 4-1BB-CD3ζ LV20.19 CAR T cells and the feasibility of on-site manufacturing using the CliniMACS Prodigy system. CAR T cell doses ranged from 2.5 × 10⁵-2.5 × 10⁶ cells per kg. Cell manufacturing was set at 14 d with the goal of infusing non-cryopreserved LV20.19 CAR T cells. The target dose of LV20.19 CAR T cells was met in all CAR-naive patients, and 22 patients received LV20.19 CAR T cells on protocol. In the absence of dose-limiting toxicity, a dose of 2.5 × 10⁶ cells per kg was chosen for expansion. Grade 3-4 cytokine release syndrome occurred in one (5%) patient, and grade 3-4 neurotoxicity occurred in three (14%) patients. Eighteen (82%) patients achieved an overall response at day 28, 14 (64%) had a complete response, and 4 (18%) had a partial response. The overall response rate to the dose of 2.5 × 10⁶ cells per kg with non-cryopreserved infusion (n = 12) was 100% (complete response, 92%; partial response, 8%). Notably, loss of the CD19 antigen was not seen in patients who relapsed or experienced treatment failure. In conclusion, on-site manufacturing and infusion of non-cryopreserved LV20.19 CAR T cells were feasible and therapeutically safe, showing low toxicity and high efficacy. Bispecific CARs may improve clinical responses by mitigating target antigen downregulation as a mechanism of relapse.

Actovegin® reduces PMA-induced inflammation on human cells

Purpose

The effect of Actovegin® was investigated on PMA- and LPS-induced human peripheral blood mononuclear cells (PBMCs).

Methods

PBMCs (1 × 10⁶ cells/ml) from five blood donors (2 f, 3 m; 45–55 years) were grown in medium and exposed to Actovegin® in the presence or absence of PMA or LPS. Supernatants were collected to assess the concentration of cytokines (TNF-α, IL-1beta, IL-6 and IL-10). The reactive oxygen species (ROS) were assessed by a ROS-Glo^TM H₂O₂ assay.

Results

Stimulation of cells by PMA or LPS (without Actovegin®) significantly increased the secretion of IL-1beta, IL-6, IL-10 and TNF-α from PBMCs, compared to controls. Pre-treatment of cells with Actovegin® (1, 5, 25, 125 µg/ml) plus PMA significantly decreased the secretion of IL-1beta from PBMCs, compared to controls (PMA without Actovegin®). In contrast, addition of Actovegin® (1, 5, 25, 125 and 250 µg/ml) plus LPS did not alter the IL-1beta production, compared to controls (LPS without Actovegin®). TNF-α, IL-6 and IL-10 do not contribute to the reduction of inflammatory reactions with Actovegin®.

Conclusions

Actovegin® can reduce the PMA-induced IL-1beta release and the ROS production from PBMCs. These findings may help to explain the clinically known positive effects of Actovegin® on athletic injuries with inflammatory responses (e.g., muscle injuries, tendinopathies).

Understanding the freezing responses of T cells and other subsets of human peripheral blood mononuclear cells using DSMO-free cryoprotectants

BACKGROUND

This study examined the freezing responses of peripheral blood mononuclear cells (PBMCs) and specific white blood cell subsets contained therein when cryopreserved in three combinations of osmolytes composed of sugars, sugar alcohols and amino acids.

METHODS

A differential evolution algorithm with multiple objectives was used to optimize cryoprotectant composition and thus the post-thaw recoveries for both helper and cytotoxicity T cells simultaneously.

RESULTS

The screening of various formulations using a differential evolution algorithm showed post-thaw recoveries greater than 80% for the two subsets of T cells. The phenotypes and viabilities of PBMC subsets were characterized using flow cytometry. Significant differences between the post-thaw recovery for helper T cells and cytotoxic T cells were observed. Statistical models were used to analyze the importance of individual osmolytes and interactions between post-thaw recoveries of three subsets of T cell including helper T cells, cytotoxic T cells and natural killer T cells. The statistical model indicated that the preferred concentration levels of osmolytes and interaction modes were distinct between the three subsets studied. PBMCs were cultured for 72 h post-thaw to determine the stability of the cells. Because post-thaw apoptosis is a significant concern for lymphocytes, apoptosis of helper T cell and cytotoxic T cells frozen in a DMSO-free cryoprotectant was analyzed immediately post-thaw and 24 h post-thaw. Both cell types showed a decrease in cell viability 24 h post-thaw compared with immediately post-thaw. Helper T cell viability dropped 17%, and cytotoxic T cells had a 10% drop in viability. Immediately post-thaw, both cell types had >30% of cells in early apoptosis, but after 24 h the number of cells in early apoptosis decreased to below 20%.

CONCLUSION

This study helped us identify the freezing responses of different human PBMC subsets using combinations of osmolytes.

Variability of ex-vivo stimulated T-cells secretory profile in healthy subjects

Peripheral blood lymphocytes (PBL) are able to synthesize various cytokines that play key roles in the immune response and intercellular signaling. Since alterations in cytokine production and/or activity occur in many pathological processes, the study of cytokine synthetic capacity of PBL is a valuable tool for assessing the immune profile. In this paper, we aimed to investigate the variability of interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α) and interferon gamma (IFN-γ) synthetic capacity of CD4+/CD8+ T-cells stimulated ex-vivo in healthy subjects, by means of a commercial intracellular cytokine staining (ICS) protocol. Peripheral blood mononuclear cells were isolated from 16 healthy subjects by Ficoll gradient centrifugation and activated ex-vivo with PMA/Ionomycin/Brefeldin-A for 4 hours. Activated PBL were surface-stained for CD3/CD4/CD8, fixed and permeabilized. ICS was performed using anti-human IL-2/TNF-α/IFN-γ and samples were analyzed on a BD-FACSAria-III flow cytometer. We recorded high post-isolation and post-activation mean viabilities: 82.1% and 82.4% respectively, p=0.84. Both CD4+/CD8+ subpopulations were found to partially produce each of the three cytokines, but in different proportions. On average, a significantly greater percentage of CD4+ cells was shown to produce IL-2 and TNF-α, compared with CD8+ cells (61.5%+/-5.8 vs. 25%+/-5.6 and 26.9%+/-11 vs. 7.5%+/-3.3 respectively, p---lt---0.0001 for both). Contrarily, IFN-γ was produced by a higher proportion of CD8+ cells (8.4%+/-3.9 vs. 6.8%+/-3.2, p=0.01). These results show that the employed ICS protocol elicits a satisfactory and consistent cytokine response from PBL of healthy subjects. The collected data may be used to outline a preliminary reference range for future studies on both healthy/pathological subjects.

No Evidence for Circulating Retina Specific Autoreactive T-cells in Latent Tuberculosis-associated Uveitis and Sarcoid Uveitis

Purpose: To detect circulating retina-specific autoreactive CD4⁺ T-cells and antiretinal antibodies (ARA) in latent tuberculosis (TB)-associated uveitis or sarcoid uveitis patients.Methods: The presence of crude retinal extract (RE) autoreactive CD4⁺ T-cells was determined by a highly sensitive flowcytometric-based technique examining co-expression of CD25 and CD134 (OX40) on RE stimulated PBMC. The presence of ARA in available matched serum samples was assessed by indirect immunofluorescence.Results: No autoreactive CD4⁺ T-cells against RE could be detected in either latent TB-associated uveitis or sarcoid uveitis patients, while ARA were detected in the serum of the majority (5/6) of latent TB-associated uveitis and all (3/3) sarcoid uveitis patients.Conclusion: Even with the use of this highly sensitive flowcytometric technique circulating retina-specific autoreactive CD4⁺ T-cells could not be detected. In contrast, ARA were detected in the majority of patients indicating an adaptive humoral immune response toward retinal antigens had occurred.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

Development of a BiTE®-mediated CD8+ cytotoxic T-lymphocyte activity assay to assess immunomodulatory potential of drug candidates in Cynomolgus macaque

The immunotoxic potential of drug candidates is assessed through the examination of results from a variety of studies and endpoints. While the functional assessment of CD8⁺ cytotoxic T-lymphocytes (CTL) is well-characterized in the clinic, the lack of a robust macaque CTL functional assay has been an important hurdle in evaluating and accurately quantifying cell-mediated CD8⁺ T-cell effector responses in the nonclinical setting. This paper describes the development of an assay to measure CTL activity in peripheral blood mononuclear cells (PBMC) isolated from Cynomolgus macaques. A human EGFR/CD3 Bispecific T-cell Engager (BiTE^®) was used to mount a robust CD8⁺ T-cell response in the presence of target-expressing cells. Upon target engagement, degranulation of CD107a and production of interferon (IFN)-γ both reliably indicated a robust functional response in CD8⁺ T-cells. The BiTE^®-mediated stimulation method proved to be favorable when compared to other methods of stimulation in the absence of target cells. These studies demonstrated acceptable longitudinal variability of the functional assay and sensitivity to dexamethasone-mediated immunosuppression. Taken together, the results indicated an assay leveraging CD3-bispecific antibodies and target-expressing cells can provide a robust approach to the in vitro or ex vivo assessment of CTL function in Cynomolgus macaques. Because the impairment of CTL activity by immunomodulators is recognized to be an important contributor to decreased antiviral defense and increased carcinogenicity risk, we believe that this novel assay to be a valuable addition to the immunotoxicology assessment of therapeutic drug candidates.

Effect of peripheral blood mononuclear cell cryopreservation on innate and adaptive immune responses

Cryopreservation of blood-derived immune cells is commonly used in clinical trials to examine immunological responses. However, studies elucidating the effects of cryopreservation on peripheral blood mononuclear cell (PBMC) responses have shown inconsistent results making it difficult to draw meaningful conclusions. Therefore we sought to address this issue by comparing key innate and adaptive immune parameters between freshly-isolated and cryopreserved PBMCs from healthy adults. We examined the effect of cryopreservation on the expression of key markers on innate and adaptive immune cell populations (i.e. CD4+ and CD8+ [T cells], CD14+ [monocytes], CD19+ [B cells], CD56+ [NK cells] or CD19 + CD27+ [memory B cells]), on cytokine secretion (TNF-α, INF-γ, IL-1β, IL-10, IL-6, MCP-1 and RANTES) in cultured PBMC supernatants following stimulation with a range of Toll-like receptor (TLR) agonists, as well as on antigen-specific memory B cell enumeration by ELISpot. We found that cryopreservation had no effect on the expression of immune markers on innate and adaptive immune cells as well on the number of antigen-specific memory B cells. However, the response to TLR ligands such as FLA-ST, CpG and LPS was variable with increased cytokine production by cryopreserved PBMCs observed compared to freshly-isolated PBMCs. Our results suggest that the effect of cryopreservation on the biological response of immune cell populations needs to be carefully considered, particularly in the context of clinical studies that rely on these immune outcomes.

Susceptibility of A. fumigatus-specific T-cell assays to pre-analytic blood storage and PBMC cryopreservation greatly depends on readout platform and analytes

Mould-specific T cells detectable by flow cytometry or ELISPOT were proposed as a novel biomarker in invasive aspergillosis. To define protocols facilitating sample shipment and longitudinal analysis, this study evaluated the susceptibility of different functional assays for A. fumigatus-specific T-cell quantification and characterisation to pre-analytic delays. PBMCs from 6 healthy donors were analysed after immediate isolation, after 6 hours whole blood storage or after cryopreservation using 3 different common media. Functional responses to A. fumigatus lysate stimulation were comparatively assessed by flow cytometry, ELISPOT and 14-plex cytokine assay. After 6 hours pre-analytic storage, all functional assays showed reduced detection rates, higher coefficients of variation (CV) and widely varying individual recovery indices of specific T-cell response. While cryopreservation resulted in sufficient yields and largely unaltered cellular composition, outcomes of functional readouts significantly differed from freshly processed samples. For CD154-based flow cytometry, only cryopreservation in RPMI supplemented with autologous serum resulted in satisfactory detection rates and CVs. For ELISPOT and cytokine secretion assays, none of the cryopreservation protocols provided sufficient concordance with immediately processed samples. Even using the same readout platform, individual analytes widely varied in their susceptibility to cryopreservation, highlighting that distinct optimisation is required depending on the downstream assay.

Evaluating Cytokines in Immunotoxicity Testing

One of the most powerful tools in immunotoxicology is the assessment of cytokines, the proteins/peptides responsible for regulating a variety of processes including immunity, inflammation, apoptosis, and hematopoiesis. Cytokine production measurements offer outstanding information and may eventually substitute for other more laborious procedures in the assessment of immunotoxicity. The particular profile of cytokine production provides indeed important information regarding the nature of many immunotoxic responses.Recent expansion in the knowledge of cytokine biology and the realization that cytokines play a role in human diseases have created a need for the precise assessment and accurate interpretation of their presence and activity in body fluids, tissues, and cells. Proper evaluation of cytokines requires attention to several technical details. Multi-cytokine analysis still needs to be standardized in terms of optimum source for analysis, protocols, and quality control issues, such as the use of reference standards and the expression of results.Important practical details and considerations will be discussed in this chapter, including the source of the sample to be tested (circulating fluids or ex vivo/in vitro isolated cells); the potential effects of collection, processing, and storage of the results of the assays, as well as potential variables associated with the source material (matrix effects, relevance, inhibitory substances); and factors influencing the choice of assay used (bioassay, immunoassay, molecular biology technique, flow cytometry).

The state of T cells before cryopreservation: Effects on post-thaw proliferation and function

AIM

We aim to assess the effect of the state of T cells before cryopreservation on the post-thaw proliferative capacity, phenotype and functional response.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from a hepatocellular carcinoma (HCC) patient, and the T cells were frozen during cell culture according to our experimental design. After a period of re-culture, the proliferative capacity of the cryopreserved cells, the expression of T cell surface markers and the secretion of IFN-γ and IL-10 were assayed.

RESULTS

There was >90% cell viability after thaw in every group. Lymphocytes cryopreserved at day 4, 8 or 12 during the cell culture were allowed to recover for 24 h, whereas lymphocytes cryopreserved while freshly isolated were allowed to recover for 72 h. After the period of re-culture, cryopreservation at day 4, 8 or 12 during T cell culture was not found to alter the T cell subpopulation. The proportions of NKT and Treg cells were unchanged when cells were cryopreserved at day 12 during T cell culture. IFN-γ secretion was not impacted by cryopreservation, and IL-10 secretion was significantly decreased when cells were cryopreserved at day 8 or 12 during T cell culture.

CONCLUSION

The state of T cells before cryopreservation has effects on the post-thaw proliferation capacity, the phenotype and the secretion of IFN-γ and IL-10. Cryopreservation of lymphocytes at day 8 or 12 during the cell culture may be the best choice for T cell immunotherapy.

A calcineurin antifungal strategy with analogs of FK506

A novel antifungal strategy targeting the inhibition of calcineurin is described. To develop a calcineurin based inhibitor of pathogenic fungi, analogs of FK506 were synthesized that were able to permeate mammalian but not fungal cells. Antagonists in combination with FK506 were not immunosuppressive and retained antifungal activity in A. fumigatus. To reduce the dosage burden of the antagonist, murine oral PK was improved an order of magnitude relative to previous FK506 antagonists.

Exposure to a farm environment is associated with T helper 1 and regulatory cytokines at age 4.5 years

BACKGROUND

Farm exposure has been shown to protect from childhood asthma and allergic diseases, but underlying immunological mechanisms are not clear yet.

OBJECTIVE

To explore whether farming lifestyle determines cytokine profile of peripheral blood mononuclear cells (PBMCs) of 4.5-year-old children (n = 88) from the Finnish PASTURE birth cohort study.

METHODS

We analysed regulatory (IL-10, IL-2), T helper 1 (Th1)-associated (IL-12, IFN-γ), inflammatory (IL-1β, TNF, CXCL8) and Th2-associated (IL-13) cytokines in unstimulated PBMCs and after a short-term (5 h) stimulation with lipopolysaccharide (LPS). Specific farm exposures (stables, hay barn, farm milk) at age 4 years were assessed from questionnaires.

RESULTS

The unstimulated PBMCs of farm children produced more IL-10 (GMR 1.22, P = 0.032), IL-12 (GMR 1.24, P = 0.012) and IFN-γ (GMR 1.24, P = 0.024) than those of non-farm children. Also, specific farm exposures were associated with higher spontaneous production of cytokines. The number of specific farm exposures tended to be dose dependently associated with higher spontaneous production of IFN-γ (test for trends, P = 0.013) and lower LPS-induced production of TNF (test for trends, P = 0.025).

CONCLUSION AND CLINICAL RELEVANCE

Farming lifestyle seemed to be associated with increased spontaneous production of Th1 and regulatory cytokines. Decreased TNF responses to short-term LPS stimulation in farm-exposed children may imply tolerogenic immune mechanisms. These novel findings might contribute to the asthma and allergy protection in farm environment.

Quantification of A. fumigatus-specific CD154+ T-cells-preanalytic considerations

Fungal specific CD154⁺ T-cells have been described as a biomarker in invasive aspergillosis. The influence of sample storage on the detection of these cells was assessed. Six-hour delay prior to PBMC isolation is associated with an 18% decrease of cell viability and alterations of the cellular composition of the sample. This results in 87% reduction of CD154⁺ A. fumigatus specific cells due to reduced assay sensitivity and increased background values in unstimulated samples. If prompt cell measurement is not feasible, isolated PBMCs can be frozen (at -20°C and -80°C) and processed later with comparable assay reliability (mean value fresh vs. thawing: 0.126, 0.133; Pearson-Coefficient: 0.962).

Effect of storage conditions on subpopulations of peripheral blood T lymphocytes isolated from naïve cattle and cattle infected with foot-and-mouth disease virus

BACKGROUND

Immunophenotyping of blood lymphocytes by flow cytometry is important in infectious disease research. In animal experiments and other longitudinal studies, the processing, prompt staining, and analysis of fresh samples is a logistical challenge and daily assay variation can confound data interpretation.

OBJECTIVE

This study examined the feasibility of cryopreservation and deferred analysis of bovine peripheral blood T lymphocytes from normal or infected animals.

METHODS

Peripheral blood mononuclear cells were collected from 4 naïve Holstein steers and 4 steers infected with foot-and-mouth-disease virus serotype Asia1. Identical aliquots were labeled and analyzed immediately, labeled for deferred analysis, or stored at -70°C or over liquid nitrogen for up to 3 weeks before labeling.

RESULTS

Freezing of unlabeled cells induced statistically significant changes in phenotypic recognition. In infected animals, the γδ T-cell population increased by 28% and CD8(+) αβT cells by 32%, while total CD3(+) cells decreased by 16%, and CD4(+) αβT cells decreased by 12%. Subsequent storage of frozen cells for the duration of the study, however, had no significant effect. There was less than 20% relative change in subpopulation sizes, and storage at -70°C or over liquid nitrogen was equivalent.

CONCLUSIONS

Depending on the objectives and practical limitations of a study, deferred labeling of peripheral blood lymphocytes can be a viable option. Although frozen storage of lymphocytes can introduce some artifactual distortion of relative cell populations, frozen cells can be maintained in storage until all samples in a longitudinal study can be analyzed in batch under standardized conditions and without introducing further bias.

Antigen-specific T cells fully conserve antitumour function following cryopreservation

Immunotherapies based on the autologous adoptive transfer of ex vivo-manipulated T cells are rapidly evolving for the treatment of both metastatic and primary malignancies. However, extended ex vivo culturing reduces the functionality of isolated T cells. Cryopreservation of rapidly expanded T cells for subsequent use throughout an immunotherapeutic regimen is a highly desirable recourse, thus far encumbered by a lack of studies investigating its effects on effector T-cell functionality. Here we directly compare murine tumour-reactive CD8⁺ T cells cryopreserved during ex vivo expansion to freshly isolated populations. We show that cryopreservation fully conserves the differentiation potential of effector T cells, secretion of pro-inflammatory cytokines, cytotoxic function and does not impair the three-dimensional scanning motility of T cells or their capacity to infiltrate and reject tumours.

An In Vitro Model for Measuring Immune Responses to Malaria in the Context of HIV Co-infection

Malaria and HIV co-infection is a growing health priority. However, most research on malaria or HIV currently focuses on each infection individually. Although understanding the disease dynamics for each of these pathogens independently is vital, it is also important that the interactions between these pathogens are investigated and understood. We have developed a versatile in vitro model of HIV-malaria co-infection to study host immune responses to malaria in the context of HIV infection. Our model allows the study of secreted factors in cellular supernatants, cell surface and intracellular protein markers, as well as RNA expression levels. The experimental design and methods used limit variability and promote data reliability and reproducibility. All pathogens used in this model are natural human pathogens (Plasmodium falciparum and HIV-1), and all infected cells are naturally infected and used fresh. We use human erythrocytes parasitized with P. falciparum and maintained in continuous in vitro culture. We obtain freshly isolated peripheral blood mononuclear cells from chronically HIV-infected volunteers. Every condition used has an appropriate control (P. falciparum parasitized vs. normal erythrocytes), and every HIV-infected donor has an HIV uninfected control, from which cells are harvested on the same day. This model provides a realistic environment to study the interactions between malaria parasites and human immune cells in the context of HIV infection.

Effects of blood transportation on human peripheral mononuclear cell yield, phenotype and function: implications for immune cell biobanking

Human biospecimen collection, processing and preservation are rapidly emerging subjects providing essential support to clinical as well as basic researchers. Unlike collection of other biospecimens (e.g. DNA and serum), biobanking of viable immune cells, such as peripheral blood mononuclear cells (PBMC) and/or isolated immune cell subsets is still in its infancy. While certain aspects of processing and freezing conditions have been studied in the past years, little is known about the effect of blood transportation on immune cell survival, phenotype and specific functions. However, especially for multicentric and cooperative projects it is vital to precisely know those effects. In this study we investigated the effect of blood shipping and pre-processing delay on immune cell phenotype and function both on cellular and subcellular levels. Peripheral blood was collected from healthy volunteers (n = 9): at a distal location (shipped overnight) and in the central laboratory (processed immediately). PBMC were processed in the central laboratory and analyzed post-cryopreservation. We analyzed yield, major immune subset distribution, proliferative capacity of T cells, cytokine pattern and T-cell receptor signal transduction. Results show that overnight transportation of blood samples does not globally compromise T- cell subsets as they largely retain their phenotype and proliferative capacity. However, NK and B cell frequencies, the production of certain PBMC-derived cytokines and IL-6 mediated cytokine signaling pathway are altered due to transportation. Various control experiments have been carried out to compare issues related to shipping versus pre-processing delay on site. Our results suggest the implementation of appropriate controls when using multicenter logistics for blood transportation aiming at subsequent isolation of viable immune cells, e.g. in multicenter clinical trials or studies analyzing immune cells/subsets. One important conclusion might be that despite changes due to overnight shipment, highly standardized central processing (and analysis) could be superior to multicentric de-central processing with more difficult standardization.

Processing of blood samples influences PBMC viability and outcome of cell-mediated immune responses in antiretroviral therapy-naïve HIV-1-infected patients

Intracellular cytokine staining (ICS) assay is increasingly used in vaccine clinical trials to measure antigen-specific T-cell mediated immune (CMI) responses in cryopreserved peripheral blood mononuclear cells (PBMCs) and whole blood. However, recent observations indicate that several parameters involved in blood processing can impact PBMC viability and CMI responses, especially in antiretroviral therapy (ART)-naïve HIV-1-infected individuals. In this phase I study (NCT01610427), we collected blood samples from 22 ART-naïve HIV-1-infected adults. PBMCs were isolated and processed for ICS assay. The individual and combined effects of the following parameters were investigated: time between blood collection and PBMC processing (time-to-process: 2, 7 or 24 h); time between PBMC thawing and initiation of in vitro stimulation with HIV-1 antigens (resting-time: 0, 2, 6 and 18 h); and duration of antigen-stimulation in PBMC cultures (stimulation-time: 6h or overnight). The cell recovery after thawing, cell viability after ICS and magnitude of HIV-specific CD8(+) T-cell responses were considered to determine the optimal combination of process conditions. The impact of time-to-process (2 or 4 h) on HIV-specific CD8(+) T-cell responses was also assessed in a whole blood ICS assay. A higher quality of cells in terms of recovery and viability (up to 81% and >80% respectively) was obtained with shorter time-to-process (less than 7 h) and resting-time (less than 2 h) intervals. Longer (overnight) rather than shorter (6 h) stimulation-time intervals increased the frequency of CD8(+)-specific T-cell responses using ICS in PBMCs without change of the functionality. The CD8(+) specific T-cell responses detected using fresh whole blood showed a good correlation with the responses detected using frozen PBMCs. Our results support the need of standardized procedures for the evaluation of CMI responses, especially in HIV-1-infected, ART-naïve patients.

Rapid expansion of T cells: Effects of culture and cryopreservation and importance of short-term cell recovery

BACKGROUND

Successful cell therapy relies on the identification and mass expansion of functional cells for infusion. Cryopreservation of cells is an inevitable step in most cell therapies which also entails consequences for the frozen cells.

MATERIAL AND METHODS

This study assessed the impact of cryopreservation and the widely used protocol for rapid expansion of T lymphocytes. The effects on cell viability, immunocompetence and the impact on apoptotic and immunosuppressive marker expression were analyzed using validated assays.

RESULTS AND CONCLUSION

Cryopreservation of lymphocytes during the rapid expansion protocol did not affect cell viability. Lymphocytes that underwent mass expansion or culture in high dose IL-2 were unable to respond to PHA stimulation by intracellular ATP production immediately after thawing (ATP = 16 ± 11 ng/ml). However, their reactivity to PHA was regained within 48 hours of recovery (ATP = 356 ± 61 ng/ml). Analysis of mRNA levels revealed downregulation of TGF-β and IL-10 at all time points. Culture in high dose IL-2 led to upregulation of p73 and BCL-2 mRNA levels while FoxP3 expression was elevated after culture in IL-2 and artificial TCR stimuli. FoxP3 levels decreased after short-term recovery without IL-2 or stimulation. Antigen specificity, as determined by IFNγ secretion, was unaffected by cryopreservation but was completely lost after addition of high dose IL-2 and artificial TCR stimuli. In conclusion, allowing short-time recovery of mass expanded and cryopreserved cells before reinfusion could enhance the outcome of adoptive cell therapy as the cells regain immune competence and specificity.

Optimal thawing of cryopreserved peripheral blood mononuclear cells for use in high-throughput human immune monitoring studies

Cryopreserved peripheral blood mononuclear cells (PBMC) constitute an important component of immune monitoring studies as they allow for efficient batch- testing of samples as well as for the validation and extension of original studies in the future. In this study, we systematically test the permutations of PBMC thawing practices commonly employed in the field and identify conditions that are high and low risk for the viability of PBMC and their functionality in downstream ELISPOT assays. The study identifies the addition of ice-chilled washing media to thawed cells at the same temperature as being a high risk practice, as it yields significantly lower viability and functionality of recovered PBMC when compared to warming the cryovials to 37 °C and adding a warm washing medium. We found thawed PBMC in cryovials could be kept up to 30 minutes at 37 °C in the presence of DMSO before commencement of washing, which surprisingly identifies exposure to DMSO as a low risk step during the thawing process. This latter finding is of considerable practical relevance since it permits batch-thawing of PBMC in high-throughput immune monitoring environments.

Towards a xeno-free and fully chemically defined cryopreservation medium for maintaining viability, recovery, and antigen-specific functionality of PBMC during long-term storage

Analysis of cryopreserved peripheral mononuclear cells (PBMC) is important for evaluating new vaccines in immune based therapies and in pathogenesis studies. To ensure comparable assay results from different laboratories and points of time, collaborative research in multicenter trials needs reliable and reproducible cryopreservation protocols that maintain cell viability and functionality. Current cryomedia consist largely of fetal bovine serum (FBS), a natural mix of growth factors, cytokines, and undefined compounds. Standardized procedures are not possible, as FBS can affect the antigen-specific T-cell response, the most important parameter in functionality assays. Also, worldwide sample exchange is complicated by the strict import restrictions on FBS, because of transfection risk. After establishing a serum-free cryopreservation protocol that maintains cell viability, recovery and antigen-specific T-cell response of PBMC comparably to FBS-based cryomedia (Germann et al., 2011), the aim of this study was the complete avoidance of animal proteins and products in combination with efficient cryopreservation. As long-term stability of the cryopreservation process is crucial for retrospective evaluation of samples at different points of time, PBMC were analyzed after storage for maximal four weeks and again after approximately six months. The cryopreservation efficiency of the protein-free and fully chemically defined cryomedium was comparable to FBS-medium after storage for few weeks and several months. Directly after thawing, this medium yielded viabilities over 97% and recovery values over 84%. Also, the specific T-cell functionality was preserved. Additionally, short-term and six month cryopreservation gave comparable results. The fully chemically defined medium presented here will increase standardization and reproducibility of analysis in multicenter-studies or in retrospective evaluation.

A comparative in vitro study of the effects of separate and combined products of Citrus e fructibus and Cydonia e fructibus on immunological parameters of seasonal allergic rhinitis

This paper examined the effects of the combined product, Citrus e fructibus/Cydonia e fructibus (Citrus/Cydonia; Citrus and Cydonia: each 0.01 g/mL), and separate products of Citrus (0.01 g/mL) and Cydonia (0.01 g/mL) on the immunological pathways involved in seasonal allergic rhinitis (SAR). Peripheral blood mononuclear cells (PBMCs) from five healthy and five grass pollen-allergic donors were isolated and analyzed in vitro after polyclonal and allergen-specific stimulation of T cells in the presence of the three extracts. The analyses demonstrated acceptable cell survival with no signs of toxicity. Citrus mainly had a selective effect on reducing allergen-specific chronic inflammatory (TNF-α; Citrus compared to Cydonia and Citrus/Cydonia: −87.4 (P < 0.001) and −68.0 (P < 0.05), resp.) and Th2 pathway activity (IL-5; Citrus compared to Cydonia: −217.8 (P < 0.01); while, both Cydonia and Citrus/Cydonia mainly affected the induction of the allergen-specific Th1 pathway (IFN-γ; Cydonia and Citrus/Cydonia compared to Citrus: 3.8 (P < 0.01) and 3.0 (P < 0.01), resp.). Citrus and Cydonia demonstrated different working mechanisms in the treatment of SAR and the combination product did not demonstrate larger effects than the separate preparations. Further effectiveness and efficacy studies comparing the effects of the products on SAR in vivo are indicated.

Comparison of cryopreservation methods on T-cell responses to islet and control antigens from type 1 diabetic patients and controls

BACKGROUND

Type 1 diabetes (T1D) is a cell-mediated autoimmune disease characterized by destruction of the pancreatic islet cells. The use of cryopreserved cells is preferable to the use of freshly isolated cells to monitor clinical trials to decrease assay and laboratory variability.

METHODS

The T-Cell Workshop Committee of the Immunology of Diabetes Society compared two widely accepted T-cell freezing protocols (warm and cold) to freshly isolated peripheral blood mononuclear cells from patients with T1D and controls in terms of recovery, viability, cell subset composition, and performance in functional assays currently in use in T1D-related research. Nine laboratories participated in the study with four different functional assays included.

RESULTS

The cold freezing method yielded higher recovery and viability compared with the warm freezing method. Irrespective of freezing protocol, B cells and CD8+ T cells were enriched, monocyte fraction decreased, and islet antigen-reactive responses were lower in frozen versus fresh cells. However, these results need to take in to account that the overall response to islet autoantigens was low in some assays.

CONCLUSIONS

In the current study, none of the tested T-cell functional assays performed well using frozen samples. More research is required to identify a freezing method and a T-cell functional assay that will produce responses in patients with T1D comparable to responses using fresh peripheral blood mononuclear cells.

Induced cytokine response of human PMBC-cultures: correlation of gene expression and secretion profiling and the effect of cryopreservation

The immune system is regulated by the complex interaction of multiple cytokines, which are secreted signaling molecules affecting other cells. In this work, we studied the cytokine response to several well-known stimulants, such as OKT-3, Con A, PWM, and SEB. Healthy donor cells (PBMCs) were cultivated for up to 72 h and the mRNA levels and cytokine release of four key cytokines (IL-2, IL-4, IFN-γ, and TNF-α) were analyzed by RT-PCR and bead-based multiplex analyses. The generated cytokine profiles showed characteristic expression patterns and secretion kinetics for each cytokine and substance. PWM/SEB and OKT-3 led to a very fast and long-lasting immune response, whereas Con A induced the slowest cytokine production. Cytokine concentrations also differed greatly. The highest IFN-γ concentration was 1000 times higher than the respective IL-4 concentration. Gene expression and cytokine concentration profiles were strongly correlated during the time course. The chronological response of the donors' cytokine profiles coincided, but showed individual characteristics regarding the strength of the cytokine release. The comparison of stimulation experiments using freshly isolated and cryopreserved PBMCs showed that, for the observation of an immunological response at early points in time, gene expression experiments are more reliable than the measurement of cytokines in the cell culture supernatant. However, the freezing of cells influences the response significantly. The measurement of secreted proteins is the superior method at later points in time.

Effect of heating and glycation on the allergenicity of 2S albumins (Ara h 2/6) from peanut

Background

Peanut allergy is one of the most common and severe food allergies, and processing is known to influence the allergenicity of peanut proteins. We aimed to establish the effect of heating and glycation on the IgE-binding properties and biological activity of 2S albumins (Ara h 2/6) from peanut.

Methodology/Principal Findings

Native Ara h 2/6 was purified from raw peanuts and heated in solution (15 min, 110°C) in the presence or absence of glucose. Ara h 2 and 6 were also purified from roasted peanut. Using PBMC and sera from peanut-allergic patients, the cellular proliferative potency and IgE reactivity (reverse EAST inhibition) and functionality (basophil degranulation capacity) of allergens were assessed. Heating Ara h 2/6 at 110°C resulted in extensive denaturation, hydrolysis and aggregation of the protein, whilst Ara h 2 and 6 isolated from roasted peanut retained its native conformation. Allergen stimulation of PBMC induced proliferation and Th2 cytokine secretion which was unaffected by thermal processing. Conversely, IgE reactivity and functionality of Ara h 2/6 was decreased by heating. Whilst heating-glycation further reduced the IgE binding capacity of the proteins, it moderated their loss of histamine releasing capacity. Ara h 2 and 6 purified from roasted peanut demonstrated the same IgE reactivity as unheated, native Ara h 2/6.

Conclusions/Significance

Although no effect of processing on T-cell reactivity was observed, heat induced denaturation reduced the IgE reactivity and subsequent functionality of Ara h 2/6. Conversely, Ara h 2 and 6 purified from roasted peanut retained the structure and IgE reactivity/functionality of the native protein which may explain the allergenic potency of this protein. Through detailed molecular study and allergenicity assessment approaches, this work then gives new insights into the effect of thermal processing on structure/allergenicity of peanut proteins.

Citrus/Cydonia Compositum Subcutaneous Injections versus Nasal Spray for Seasonal Allergic Rhinitis: A Randomized Controlled Trial on Efficacy and Safety

Background. Clinical experiences in vitro and clinical studies have demonstrated the curative potency and safety of Citrus/Cydonia compositum in seasonal allergic rhinitis treatment. Objectives. To compare the efficacy and safety of two routes of administration (nasal spray versus subcutaneous injections). Methodology: Design. a national, randomised, comparative clinical trial with two parallel groups. Participants. 23 patients fulfilled the study requirements. Intervention. after a one- or two-week wash-out period, 23 patients were randomized, to a 6-week treatment period. Outcomes. immunological and symptom severity changes and safety. Immunologic outcome assessments were blinded to group assignment. 23 patients were randomized and from 22/23 patients (11 in each group) blood samples were analyzed before and after treatment. Conclusion. Both routes of administration demonstrate immunological and clinical effects, with larger inflammatory and innate immunological effects of the nasal spray route and larger allergen-specific clinical effects of the subcutaneous route, and are safe.

Isolation and preservation of peripheral blood mononuclear cells for analysis of islet antigen-reactive T cell responses: position statement of the T-Cell Workshop Committee of the Immunology of Diabetes Society

Autoimmune T cell responses directed against insulin-producing β cells are central to the pathogenesis of type 1 diabetes (T1D). Detection of such responses is therefore critical to provide novel biomarkers for T1D 'immune staging' and to understand the mechanisms underlying the disease. While different T cell assays are being developed for these purposes, it is important to optimize and standardize methods for processing human blood samples for these assays. To this end, we review data relevant to critical parameters in peripheral blood mononuclear cell (PBMC) isolation, (cryo)preservation, distribution and usage for detecting antigen-specific T cell responses. Based on these data, we propose recommendations on processing blood samples for T cell assays and identify gaps in knowledge that need to be addressed. These recommendations may be relevant not only for the analysis of T cell responses in autoimmune disease, but also in cancer and infectious disease, particularly in the context of clinical trials.

Effect of nutrient deficiencies on in vitro Th1 and Th2 cytokine response of peripheral blood mononuclear cells to Plasmodium falciparum infection

Background

An appropriate balance between pro-inflammatory and anti-inflammatory cytokines that mediate innate and adaptive immune responses is required for effective protection against human malaria and to avoid immunopathology. In malaria endemic countries, this immunological balance may be influenced by micronutrient deficiencies.

Methods

Peripheral blood mononuclear cells from Tanzanian preschool children were stimulated in vitro with Plasmodium falciparum-parasitized red blood cells to determine T-cell responses to malaria under different conditions of nutrient deficiencies and malaria status.

Results

The data obtained indicate that zinc deficiency is associated with an increase in TNF response by 37%; 95% CI: 14% to 118% and IFN-γ response by 74%; 95% CI: 24% to 297%. Magnesium deficiency, on the other hand, was associated with an increase in production of IL-13 by 80%; 95% CI: 31% to 371% and a reduction in IFN-γ production. These results reflect a shift in cytokine profile to a more type I cytokine profile and cell-cell mediated responses in zinc deficiency and a type II response in magnesium deficiency. The data also reveal a non-specific decrease in cytokine production in children due to iron deficiency anaemia that is largely associated with malaria infection status.

Conclusions

The pathological sequels of malaria potentially depend more on the balance between type I and type II cytokine responses than on absolute suppression of these cytokines and this balance may be influenced by a combination of micronutrient deficiencies and malaria status.

Alterations in early cytokine-mediated immune responses to Plasmodium falciparum infection in Tanzanian children with mineral element deficiencies: a cross-sectional survey

Background

Deficiencies in vitamins and mineral elements are important causes of morbidity in developing countries, possibly because they lead to defective immune responses to infection. The aim of the study was to assess the effects of mineral element deficiencies on early innate cytokine responses to Plasmodium falciparum malaria.

Methods

Peripheral blood mononuclear cells from 304 Tanzanian children aged 6-72 months were stimulated with P. falciparum-parasitized erythrocytes obtained from in vitro cultures.

Results

The results showed a significant increase by 74% in geometric mean of TNF production in malaria-infected individuals with zinc deficiency (11% to 240%; 95% CI). Iron deficiency anaemia was associated with increased TNF production in infected individuals and overall with increased IL-10 production, while magnesium deficiency induced increased production of IL-10 by 46% (13% to 144%) in uninfected donors. All donors showed a response towards IL-1β production, drawing special attention for its possible protective role in early innate immune responses to malaria.

Conclusions

In view of these results, the findings show plasticity in cytokine profiles of mononuclear cells reacting to malaria infection under conditions of different micronutrient deficiencies. These findings lay the foundations for future inclusion of a combination of precisely selected set of micronutrients rather than single nutrients as part of malaria vaccine intervention programmes in endemic countries.

Quality monitoring of HIV-1-infected and uninfected peripheral blood mononuclear cell samples in a resource-limited setting

Human immunodeficiency virus type 1 (HIV-1) vaccine and natural history studies are critically dependent on the ability to isolate, cryopreserve, and thaw peripheral blood mononuclear cell (PBMC) samples with a high level of quality and reproducibility. Here we characterize the yield, viability, phenotype, and function of PBMC from HIV-1-infected and uninfected Ugandans and describe measures to ascertain reproducibility and sample quality at the sites that perform cryopreservation. We have developed a comprehensive internal quality control program to monitor processing, including components of method validation. Quality indicators for real-time performance assessment included the time from venipuncture to cryopreservation, time for PBMC processing, yield of PBMC from whole blood, and viability of the PBMC before cryopreservation. Immune phenotype analysis indicated lowered B-cell frequencies following processing and cryopreservation for both HIV-1-infected and uninfected subjects (P < 0.007), but all other major lymphocyte subsets were unchanged. Long-term cryopreservation did not impact function, as unstimulated specimens exhibited low background and all specimens responded to staphylococcal enterotoxin B (SEB) by gamma interferon and interleukin-2 production, as measured by intracellular cytokine staining. Samples stored for more than 3 years did not decay with regard to yield or viability, regardless of HIV-1 infection status. These results demonstrate that it is possible to achieve the high level of quality necessary for vaccine trials and natural history studies in a resource-limited setting and provide strategies for laboratories to monitor PBMC processing performance.