A flow cytometry based assay for the enumeration of regulatory T cells in whole blood

Maternal obesity is associated with a higher number of regulatory-T-cells in newborns without affecting suppression

BACKGROUND

Maternal obesity (MO) is associated with a higher risk of immune-mediated diseases in the offspring and higher leptin levels in cord blood (CB). This study evaluates the number and function of lymphocyte subtypes in CB related to MO and its relationship with leptin concentration and leptin receptor expression.

METHODS

Pregnant women with (n = 32) or without obesity (n = 41) were enrolled at delivery. Cord blood mononuclear cells were separated with Ficoll-Hypaque. B and CD4+, regulatory and effector T cells were quantified by Flow Cytometry. Cord blood leptin concentration was measured by ELISA, and the leptin receptor (sLepR) on Treg cells was determined by Flow Cytometry.

RESULTS

MO was associated with higher numbers of CD4+, Treg and effector T cells in the CB of their offspring, without differences in the suppressive function of Tregs. Female offspring had a higher number of these cells and a higher cord leptin concentration. Tregs expressed higher levels of sLepR than effector T cells, without differences between groups.

CONCLUSIONS

MO is associated with changes in the newborn's immune profile, more evident in female newborns with higher leptin concentrations. More studies are needed to identify the mechanisms by which the high levels of cord leptin in the newborn of women with obesity could affect the offspring's immune system.

Process development and validation of expanded regulatory T cells for prospective applications: an example of manufacturing a personalized advanced therapy medicinal product

BACKGROUND

A growing number of clinical trials have shown that regulatory T (Treg) cell transfer may have a favorable effect on the maintenance of self-tolerance and immune homeostasis in different conditions such as graft-versus-host disease (GvHD), solid organ transplantation, type 1 diabetes, and others. In this context, the availability of a robust manufacturing protocol that is able to produce a sufficient number of functional Treg cells represents a fundamental prerequisite for the success of a cell therapy clinical protocol. However, extended workflow guidelines for nonprofit manufacturers are currently lacking. Despite the fact that different successful manufacturing procedures and cell products with excellent safety profiles have been reported from early clinical trials, the selection and expansion protocols for Treg cells vary a lot. The objective of this study was to validate a Good Manufacturing Practice (GMP)-compliant protocol for the production of Treg cells that approaches the whole process with a risk-management methodology, from process design to completion of final product development. High emphasis was given to the description of the quality control (QC) methodologies used for the in-process and release tests (sterility, endotoxin test, mycoplasma, and immunophenotype).

RESULTS

The GMP-compliant protocol defined in this work allows at least 4.11 × 109 Treg cells to be obtained with an average purity of 95.75 ± 4.38% and can be used in different clinical settings to exploit Treg cell immunomodulatory function.

CONCLUSIONS

These results could be of great use for facilities implementing GMP-compliant cell therapy protocols of these cells for different conditions aimed at restoring the Treg cell number and function, which may slow the progression of certain diseases.

Lymphocyte Immune Response and T Cell Differentiation in Fontan Patients with protein-losing enteropathy

Background  Protein-losing enteropathy (PLE) is a severe complication of the Fontan circulation. There is increasing discussion about whether lymphatic dysregulation is involved as pathomechanism of PLE. This investigation focuses on the interplay between alteration of lymphatic cells and immunologic pathway alterations.

Methods  Micro-ribonucleic acid (miRNA) expression profiling was performed in 49 patients ( n  = 10 Fontan patients with PLE, n  = 30 Fontan patients without PLE, and n  = 9 patients with dextro-transposition of the great arteries (dTGA). miRNA pathway analysis was performed to identify significantly enriched pathways. To determine lymphocyte populations and subtypes multiparameter flow cytometry was used.

Results  miRNAs pathway analysis of Fontan patients with PLE revealed 20 significantly changed networks of which four of the ten largest were associated with immunologic processes. This finding is supported by significant T cell deficiency with decreased CD4+ count ( p  = 0.0002), altered CD4 +/CD8+ ratio, and significantly modified CD4+ ( p  < 0.0001) and CD8+ ( p  = 0.0002) T cell differentiation toward effector and terminal differentiated T cells in Fontan patients with PLE. Analyses of CD4+ T cell subsets demonstrated significantly increased frequencies of CD4+ CD25+ CD127– regulatory T cells (Treg) in Fontan patients with PLE ( p  = 0.0011).

Conclusion  PLE in Fontan patients is associated with severe lymphopenia, T cell deficiency, significant alterations of T cell differentiation, and increased Treg frequency reflecting an immune status of chronic inflammation and shortened protection against pathogens and autoimmunity. These cellular alterations seemed to be dysregulated by several miRNA controlled immunological pathways.

Correlation between serum vitamin D status and immunological changes in children affected by gastrointestinal food allergy

BACKGROUND

Low vitamin D status is linked to increased incidence of food allergy and intestinal inflammation. Whether vitamin D status is associated with immunological changes in children with gastrointestinal food allergy (GFA) remains unclear.

METHODS

Forty-nine GFA children (aged 2-11 years old) were enrolled in this study. Serum 25-hydroxyvitamin D (25OHD) level, total immunoglobulin E (IgE), specific IgE against allergens, circulating regulatory T lymphocytes (Tregs), and blood eosinophil numbers were measured.

RESULTS

Levels of serum 25OHD in the GFA children ranged 35.5-156.4nmol/L, with a mean value similar to that of the healthy controls. Compared to those with normal 25OHD (≥75nmol/L), GFA children with low 25OHD (<75nmol/L) had increased total IgE (84% vs. 54%, P<0.05), persistent blood eosinophilia (56% vs. 25%, P<0.05), and delayed resolution of symptoms after food allergen elimination (odds ratio 3.51, 95% CI 1.00-12.36, P<0.05). Among the GFA children with elevated total IgE, those with low 25OHD had lower circulatory Tregs (8.79±2.4% vs. 10.21±1.37%, P<0.05), higher total IgE (1197.5±1209.8 vs. 418.5±304.6kU/L, P<0.05), and persistent eosinophilia (0.61±0.52 vs. 0.31±0.15×10⁹cells/L, P<0.05) compared to those with normal 25OHD. In addition, serum 25OHD concentrations inversely correlated with total IgE (R=-0.434, P<0.05), and positively with Treg population (R=0.356, P<0.05).

CONCLUSION

Low serum vitamin D status correlates with stronger allergic immune response in GFA children.

Increased Expression of Programmed Cell Death-1 in Regulatory T Cells of Patients with Severe Sepsis and Septic Shock: An Observational Clinical Study

While regulatory T cells (Tregs) constitutively express programmed cell death-1 (PD-1), the role of PD-1 expression in Tregs of patients with sepsis remains unclear. Thus, we determined PD-1 expression in Tregs from the peripheral blood of patients with severe sepsis and septic shock. Seventy-eight patients with severe sepsis and 40 with septic shock, as well as 21 healthy subjects, were enrolled in this study. The percentage of peripheral blood PD-1⁺ Tregs, as well as absolute Treg counts, were compared between these three groups. PD-1 expression in Tregs and absolute Treg counts were also compared between survivors and non-survivors in patients with sepsis. PD-1 expression in Tregs increased in patients with sepsis compared to healthy controls. Conversely, absolute Treg counts were significantly decreased in patients with sepsis compared to healthy controls; patients with septic shock had the lowest absolute Treg counts. Among patients with sepsis, survivors had lower levels of PD-1 expression in Tregs, as well as higher absolute Treg counts, than non-survivors. Additionally, the percentage of PD-1⁺ Tregs correlated positively with lactate levels as well as the Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores in patients with sepsis. PD-1 was upregulated in Tregs of patients with sepsis and may indicate a state of immune dysfunction. Overexpression of PD-1 in Tregs was associated with more severe sepsis as well as poor outcomes.

Latent Cytomegalovirus (CMV) Infection Does Not Detrimentally Alter T Cell Responses in the Healthy Old, But Increased Latent CMV Carriage Is Related to Expanded CMV-Specific T Cells

Human cytomegalovirus (HCMV) primary infection and periodic reactivation of latent virus is generally well controlled by T-cell responses in healthy people. In older donors, overt HCMV disease is not generally seen despite the association of HCMV infection with increased risk of mortality. However, increases in HCMV DNA in urine of older people suggest that, although the immune response retains functionality, immunomodulation of the immune response due to lifelong viral carriage may alter its efficacy. Viral transcription is limited during latency to a handful of viral genes and there is both an IFNγ and cellular IL-10 CD4⁺ T-cell response to HCMV latency-associated proteins. Production of cIL-10 by HCMV-specific CD4⁺ T-cells is a candidate for aging-related immunomodulation. To address whether long-term carriage of HCMV changes the balance of cIL-10 and IFNγ-secreting T-cell populations, we recruited a large donor cohort aged 23–78 years and correlated T-cell responses to 11 HCMV proteins with age, HCMV IgG levels, latent HCMV load in CD14⁺ monocytes, and T-cell numbers in the blood. IFNγ responses by CD4⁺ and CD8⁺ T-cells to all HCMV proteins were detected, with no age-related increase in this cohort. IL-10-secreting CD4⁺ T cell responses were predominant to latency-associated proteins but did not increase with age. Quantification of HCMV genomes in CD14⁺ monocytes, a known site of latent HCMV carriage, did not reveal any increase in viral genome copies in older donors. Importantly, there was a significant positive correlation between the latent viral genome copy number and the breadth and magnitude of the IFNγ T-cell response to HCMV proteins. This study suggests in healthy aged donors that HCMV-specific changes in the T cell compartment were not affected by age and were effective, as viremia was a very rare event. Evidence from studies of unwell aged has shown HCMV to be an important comorbidity factor, surveillance of latent HCMV load and low-level viremia in blood and body fluids, alongside typical immunological measures and assessment of the antiviral capacity of the HCMV-specific immune cell function would be informative in determining if antiviral treatment of HCMV replication in the old maybe beneficial.

Immunophenotyping pattern characterization in canine blood: towards a clinical application

Immunophenotyping is a widely used method for a precise diagnosis and classification of haematopoietic neoplasia in human beings and also in dogs. The gold standard for cell preparation is density gradient centrifugation of mononuclear cells. Alternatively, another way to separate human leukocytes is carrying out whole blood lysis. The aim of this study was to validate whole blood lysis as an alternative method in clinical veterinary procedures using an immunophenotype panel of leukocytes designed by our group. Flow cytometry study of adult canine leukocytes subset groups, using whole blood lysis or mononuclear cells tested against an array of canine leukocyte antibodies were done. Besides differential white blood cell counts were done. Also immunophenotyping studies in whole blood samples stored at 4 °C for 48 h were performed. The Coefficient Variation values were less than 20%, for most of the comparison. Consistent results were observed in phenotyping canine peripheral blood leukocytes. Stability results indicated that whole blood samples might be stored for 48 h without a significant difference in the data compared to samples processed immediately after blood collection. This study shows that whole blood lysis represents an efficient and quick alternative for canine leukocyte preparation. In addition, samples can be analysed immediately or stored for 48 h without a significant difference between them. This is relevant for veterinary medicine considering the lack of facilities in many laboratories to process samples.

Preserved dendritic cell HLA-DR expression and reduced regulatory T cell activation in asymptomatic Plasmodium falciparum and P. vivax infection

Clinical illness with Plasmodium falciparum or Plasmodium vivax compromises the function of dendritic cells (DC) and expands regulatory T (Treg) cells. Individuals with asymptomatic parasitemia have clinical immunity, restricting parasite expansion and preventing clinical disease. The role of DC and Treg cells during asymptomatic Plasmodium infection is unclear. During a cross-sectional household survey in Papua, Indonesia, we examined the number and activation of blood plasmacytoid DC (pDC), CD141(+), and CD1c(+) myeloid DC (mDC) subsets and Treg cells using flow cytometry in 168 afebrile children (of whom 15 had P. falciparum and 36 had P. vivax infections) and 162 afebrile adults (of whom 20 had P. falciparum and 20 had P. vivax infections), alongside samples from 16 patients hospitalized with uncomplicated malaria. Unlike DC from malaria patients, DC from children and adults with asymptomatic, microscopy-positive P. vivax or P. falciparum infection increased or retained HLA-DR expression. Treg cells in asymptomatic adults and children exhibited reduced activation, suggesting increased immune responsiveness. The pDC and mDC subsets varied according to clinical immunity (asymptomatic or symptomatic Plasmodium infection) and, in asymptomatic infection, according to host age and parasite species. In conclusion, active control of asymptomatic infection was associated with and likely contingent upon functional DC and reduced Treg cell activation.

Strategies for improving the reporting of human immunophenotypes by flow cytometry

BACKGROUND

Flow cytometry is the gold standard for phenotyping and quantifying immune cells. New technologies have greatly increased our capacity to measure both routine and complex immunophenotypes. The reporting of immunophenotype data is not consistent in human studies yet it is quite critical for understanding disease specific changes, responses to immunotherapies, and normal immune homeostasis. Here we examine the barriers that hinder cross comparisons of flow cytometry data collected from human studies and clinical trials.

FINDINGS

We demonstrate that phenotypes reported as percentages within a cell compartment (i.e. myeloid derived suppressor cells as a percent of mononuclear cells) without providing data on the parent population may contribute to misleading conclusions. The enumeration of phenotypes as cell counts (cells/μl) provides a basis to more accurately compare the relationships among phenotypes. Finally, we provide evidence that density gradient centrifugation, which eliminates the ability to measure phenotypes as cell counts, can affect the expression of surface markers and consequently alter the distribution of particular immunophenotypes.

CONCLUSIONS

We propose that by measuring immunophenotypes as cell counts from minimally manipulated samples (whole blood) will improve the reporting of flow data and facilitate more direct comparisons of data across human studies.