Biological and methodological variation of lymphocyte subsets in blood of human adults

Immunomethylomic profiles of long-term head and neck squamous cell carcinoma survivors on immune checkpoint inhibitors

Aim: This study addresses the challenge of predicting the response of head and neck squamous cell carcinoma (HNSCC) patients to immunotherapy.Methods: Using DNA methylation cytometry, we analyzed the immune profiles of six HNSCC patients who showed a positive response to immunotherapy over a year without disease progression.Results: There was an initial increase in CD8 T memory cells and natural killer cells during the first four cycles of immunotherapy, which then returned to baseline levels after a year. Baseline CD8 T cell levels were lower in HNSCC immunotherapy responders but became similar to those in healthy subjects after immunotherapy.Conclusion: These findings suggest that monitoring fluctuations in immune profiles could potentially identify biomarkers for immunotherapy response in HNSCC patients.

Total error in lymphocyte subpopulations by flow cytometry-based in state of the art using Spanish EQAS data

OBJECTIVES

Flow cytometry analyses of lymphocyte subpopulations (T, B, NK) are crucial for enhancing clinical algorithms and research workflows. Estimating the total error (TE) values for the percentage and absolute number of lymphocyte subpopulations using the state-of-the-art (SOTA) approach with real data from an external proficiency testing (EPT) scheme was performed. A comparison with previously published Biological Variability (BV)-based specifications was carried out.

METHODS

A total of 44,998 results from 86 laboratories over 10 years were analysed and divided into two five-year periods (2012-2016) and (2017-2021). Data come from the IC-1 Lymphocytes scheme of the Spanish External Quality Assurance System (EQAS) GECLID Program. This quantitative scheme includes percentages and absolute numbers of CD3+, CD3+CD4+, CD3+CD8+, CD19+, and CD3-CD56+CD16+ NK cells. The percentage of TE was calculated as: |reported value - robust mean|*100/robust mean for each laboratory and parameter. The cut-off for TE is set at 80 % best results of the laboratories.

RESULTS

A significant reduction in the SOTA-based TE for all lymphocyte subpopulations in 2017-2021 was observed compared to 2012-2016. The SOTA-based TE fulfils the minimum BV-based TE for percentages of lymphocyte subpopulations. The parameter with the best analytical performance calculated with SOTA (2017-2021 period)-based TE was the percentage of CD3+ (TE=3.65 %).

CONCLUSIONS

The values of SOTA-based specifications from external quality assurance program data are consistent and can be used to develop technical specifications. The technological improvement, quality commitment, standardization, and training, reduce TE. An update of TE every five years is therefore recommended. TE assessment in lymphocyte subsets is a helpful and reliable tool to improve laboratory performance and data-based decision-making trust.

Association of Immune Cell Subsets with Incident Hip Fracture: The Cardiovascular Health Study

In this study, we aimed to evaluate the association of innate and adaptive immune cell subsets in peripheral blood mononuclear cells (PBMCs) with hip fracture. To conduct this study, we used data from the Cardiovascular Health Study (CHS), a U.S. multicenter observational cohort of community-dwelling men and women aged ≥ 65 years. Twenty-five immune cell phenotypes were measured by flow cytometry from cryopreserved PBMCs of CHS participants collected in 1998-1999. The natural killer (NK), γδ T, T helper 17 (Th17), and differentiated/senescent CD4+CD28- T cell subsets were pre-specified as primary subsets of interest. Hip fracture incidence was assessed prospectively by review of hospitalization records. Multivariable Cox hazard models evaluated associations of immune cell phenotypes with incident hip fracture in sex-stratified and combined analyses. Among 1928 persons, 259 hip fractures occurred over a median 9.7 years of follow-up. In women, NK cells were inversely associated with hip fracture [hazard ratio (HR) 0.77, 95% confidence interval (CI) 0.60-0.99 per one standard deviation higher value] and Th17 cells were positively associated with hip fracture [HR 1.18, 95% CI 1.01-1.39]. In men, γδ T cells were inversely associated with hip fracture [HR 0.60, 95% CI 0.37-0.98]. None of the measured immune cell phenotypes were significantly associated with hip fracture incidence in combined analyses. In this large prospective cohort of older adults, potentially important sex differences in the associations of immune cell phenotypes and hip fracture were identified. However, immune cell phenotypes had no association with hip fracture in analyses combining men and women.

Changes in natural killer and T lymphocyte phenotypes in response to cardiovascular risk management

The pro-inflammatory and regulatory roles of T lymphocytes in atherosclerosis are well established but less is known about natural killer (NK) cells and natural killer T (NKT)-like cells. The effects of cardiovascular risk management on the phenotypes of these cells are unknown. To assess changes in NK cell and lymphocyte phenotypes and circulating inflammatory proteins in response to cardiovascular risk management in patients with carotid atherosclerosis. Fifty patients were included in a prospective clinical study. Measurements were at baseline and after 12 months of cardiovascular risk management. Circulating NK, NKT-like and T lymphocyte subpopulations were phenotyped by multi-colour flow cytometry. Proximity extension assay was performed for 176 plasma proteins associated with inflammation and cardiovascular disease. At 12 months there were significant reductions in LDL (P = 0.001) and blood pressure (P = 0.028). NK cells responded with a reduction in pro-inflammatory (NKG2C+) cells (P = 0.0003), an increase in anti-inflammatory (NKG2A+) cells (P = 0.032), and a reduction in terminally differentiated (CD57+) NK cells. NKT-like cells showed a similar decrease in terminally differentiated subpopulations (P = 0.000002). Subpopulations of T helper cells exhibited a significant reduction in central memory (P = 1.09 × 10-8) and a significant increase in CD4+ naïve- (P = 0.0008) and effector memory T cells (P = 0.006). The protein analysis indicated that cardiovascular risk management affects proteins involved in the inflammatory NF-κB pathway. The consistent decrease in senescent phenotypes of NK, NKT-like and CD4+ cells with a concomitant increase in more naïve, phenotypes suggests a change towards a less pro-inflammatory lymphocyte profile in response to cardiovascular risk management.Trial registry name: CARotid MRI of Atherosclerosis (CARMA). ClinicalTrials.gov identifier NCT04835571 (08/04/2021). https://www.clinicaltrials.gov/study/NCT04835571 .

Altered expressions of CXCR4 and CD26 on T-helper lymphocytes in hereditary hemorrhagic telangiectasia

Background

Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic disease characterized by a deregulated neo-angiogenesis. Besides a mainly vascular phenotype (muco-cutaneous telangiectases, arteriovenous malformations), a specific risk of infection is suggested by case series of severe and atypical infections as well as by reports of decreased T and natural killer (NK) lymphocyte counts. As some evidence supports a dysregulation of the CXCR4/CXCL12 chemotactic axis of HHT endothelial cells, we hypothesized that a similar phenomenon could occur on lymphocytes.

Methods

Eighteen HHT patients with history of severe infection (HSI) were matched in age and sex with 18 HHT without HSI and 18 healthy control subjects (HC). We assessed the cell count and the surface expression of CXCR4 and CD26 (CXCL12 inactivating peptidase) of circulating T-helper and T-cytotoxic lymphocytes (including naive, memory and activated subsets) and NK cells.

Results

The overall HHT group of 36 patients exhibited a reduction of circulating T-helper lymphocytes compared to HC (median: 517 vs. 1026 cells/mm³, p < 0.0001), correlated with age (r =  − 0.46, p = 0.005), requirement of intravenous iron or blood transfusions (median: 291 vs. 627 cells/mm³, p = 0.03) and CXCR4 surface expression (r = 0.353, p = 0.0345). CXCR4 and CD26 membrane expression were both decreased on HHT T-helper lymphocytes (median MFI ratio: 4.49 vs. 5.74 for CXCR4 and 3.21 vs. 4.33 for CD26, p = 0.03 and 0.0018 respectively) with an unchanged CXCR4/CD26 ratio. The HHT group with HSI had a higher CXCR4/CD26 ratio on the total T-lymphocyte population, as well as on the T-helper population and its naive subset (median on naive T-helper cells: 2.34 vs. 1.32, p = 0.0002).

Conclusions

Our findings support a dysregulation of the CXCL12/CXCR4 chemotaxis of T-helper lymphocytes in HHT patients, potentially linked to their T-helper lymphopenia and susceptibility to infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-02139-y.

Study of total error specifications of lymphocyte subsets enumeration using China National EQAS data and Biological Variation Data Critical Appraisal Checklist (BIVAC)-compliant publications

Objectives

It is important to select proper quality specifications for laboratories and external quality assessment (EQA) providers for their quality control and assessment. The aim of this study is to produce new total error (TE) specifications for lymphocyte subset enumeration by analyzing the allowable TE using EQAS data and comparing them with that based on reliable biological variation (BV).

Methods

A total of 54,400 results from 1,716 laboratories were collected from China National EQAS for lymphocyte subset enumeration during the period 2017-2019. The EQA data were grouped according to lower limits of reference intervals for establishing concentration-dependent specifications. The TE value that 80% of laboratories can achieve were considered as TE specifications based on state of the art. The BV studies compliant with Biological Variation Data Critical Appraisal Checklist (BIVAC) were used to calculate the three levels of TE specifications. Then these TE specifications were compared for determining the recommended TE specifications.

Results

Four parameters whose quality specifications could achieve the optimum criteria were as follows: the percentages of CD3+, CD3+CD4+ (high concentration) and CD3-CD16/56+ cells, and the absolute count of CD3-CD16/56+ cells. Only the TE specifications of CD3-CD19+ cells could achieve the minimum criteria. The TE specifications of remaining parameters should reach the desirable criteria.

Conclusions

New TE specifications were established by combining the EQA data and reliable BV data, which could help laboratories to apply proper criteria for continuous improvement of quality control, and EQA providers to use robust acceptance limits for better evaluation of EQAS results.

Treatment effects of fingolimod in multiple sclerosis: Selective changes in peripheral blood lymphocyte subsets

BACKGROUND

Treatment with fingolimod reduces inflammation in multiple sclerosis (MS) by inhibiting lymphocyte egress from lymph nodes. We aimed to map, in detail, the alterations in peripheral blood lymphocyte subpopulations in relation to clinical outcome in MS patients treated with fingolimod.

METHODS

Paired blood samples from relapsing-remitting MS patients (n = 19) were collected before and after one year of treatment with fingolimod (0.5 mg/day). Absolute counts and relative proportions of a broad set of T- B- and NK-cell subsets were analyzed by flow cytometry. Blood samples from 18 healthy controls were used for baseline comparisons.

RESULTS

Treatment with fingolimod markedly decreased the absolute numbers of all major lymphocyte subsets, except for NK cells. The reduction was most pronounced within the T helper (Th) and B cell populations (p<0.001). By phenotyping differentiation status of T cells, dramatic reductions within the naïve and central memory (CM) cell populations were found (p<0.001), while a less pronounced reduction was observed among effector memory (EM) cells (p<0.001). The numbers of regulatory T cells (Tregs) were also decreased (p<0.001), but to a lesser extent than other T cell populations, resulting in a relative preservation of Tregs with a memory phenotype (p = 0.002).

CONCLUSIONS

Our results confirm that fingolimod therapy markedly reduces lymphocyte counts in peripheral blood of MS patients. Subgroup analysis of T cells showed that naïve and CM Th cells were the most profoundly affected and that memory Tregs were relatively preserved.

Biological variation of peripheral blood T-lymphocytes

BACKGROUND

Flow cytometric analysis of the lymphocyte subsets has become one of the most commonly used techniques in the routine clinical laboratory. It is frequently used in monitoring lymphocyte recovery after hematopoietic stem cell transplantation (HSCT), as well as diagnosis and treatment of acquired immunodeficiency syndrome (AIDS). Reliable biological variation (BV) data is needed for safe clinical application of these tests. In this study, similar preanalytical and analytical protocols to the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) checklist were followed and a stringent statistical approach was applied to define BV of T-lymphocytes.

METHODS

During the 10 weeks study period, weekly blood samples were obtained from 30 healthy individuals (20 females, 10 males) and analyzed with Facs Canto (BD Biosciences, San Jose, CA, USA) analyzer using 4-colour BD Multitest CD3/CD8/CD45/CD4 reagents. Data were assessed in terms of normality, tendencies, outliers and variance homogeneity prior to applying coefficient of variance (CV)- analysis of variance (ANOVA) test. Sex-stratified within-individual (CV_I) and between-individual (CV_G) BV estimates of CD3+, CD3 + CD4+, CD3 + CD8+, and CD3 + CD4 + CD8+ T lymphocytes were calculated.

RESULTS

No difference was found between males and females. Except for the CD3 + CD4 + CD8+ subset, stable BV was found for CD3+, CD3 + CD4+, and CD3 + CD8+ subsets.

CONCLUSSION

Instead of using the conventional reference ranges of CD3+, CD3 + CD4+ and CD3 + CD8+ counts for monitoring HIV positive or post-HSCT patients, RCV should be used. Because individualityis characteristic of lymphocytes subsets RCVs should be used instead of RIs for patient monitoring.

Commutability assessment of reference materials for the enumeration of lymphocyte subsets

Background Flow cytometric enumeration of lymphocyte subsets in peripheral blood can provide important information about immune status. Commutable reference materials (RM) are crucial for maintaining accurate and comparable measurement results over time and space. Commutability assessment of RMs for lymphocyte subsets enumeration has not been reported elsewhere. Methods Lymphocyte subsets were measured in triplicate on 56 patient samples and eight RMs using two measuring systems commonly used in laboratories (FACS Canto II and Cytomics FC500). The first step was to determine the suitability of RMs and comparability of different systems with patient samples. After the requirements of suitability and comparability were met, the second step was to assess commutability following regression approach and difference in bias approach. Results Two RMs were not measurable on FC500 system for CD3-CD16/56+ and CD3-CD19+ percentages. The results of comparability showed no significant difference in the two systems. Eight RMs for CD3+CD4+ cell count, six RMs for CD3+ and CD3+CD8+ percentages, five RMs for CD3-CD16/56+ percentage, and three RMs for CD3-CD19+ percentage were commutable using the two approaches. For CD3+, CD3+CD8+ and CD3-CD19+ percentages, the results of regression approach showed that one RM was non-commutable for each parameter, while the other approach showed that the RM was commutable. Conclusions The suitability of RM and comparability of different measuring systems are prerequisites for assessing commutability. This study indicated that different approaches led to different results. The difference in bias approach is recommended for criteria relating to medical requirements and performance characteristics of measuring systems in use.

Immunological and Quality-of-Life Profiles in Women with Breast Cancer: Complementary versus Conventional Care

BACKGROUND

Previous studies showed that women with breast cancer treated in anthroposophic clinic versus conventional care had increased quality of life (QoL) parameters, fighting spirit, and anxiety coping. We have now analyzed immune and QoL factors in these 2 groups for possible differences during the first 6 months after admission, prompted by anthroposophic studies, including mistletoe extracts, showing beneficial immune system effects.

PATIENTS AND METHODS

Fourteen immunological variables, including leukocyte count, lymphocyte count, activated T cells (CD4+ and CD8+), NK cells, B cells, IL1β, IL6, IL10, and oxytocin, were longitudinally analyzed in both groups (n = 2 × 26). A panel of QoL parameters were analyzed using 3 different instruments. Statistical evaluation included that each patient was its own control.

RESULTS

Cytotoxic CD8+ T cell frequency (percent of lymphocytes analyzed by flow-cytometry) significantly decreased over time in the anthroposophic group versus the conventional group (repeated measures ANOVA, p = 0.05). No major differences were observed in other immunological parameters, whereas QoL variables, anxiety decreased and physical symptoms increased/improved significantly in the anthroposophic group (p = 0.04 and p = 0.05, respectively).

CONCLUSION

Overall, women with breast cancer in anthroposophic or conventional therapy did not differ in their immune profiles over time, with exception of decreased cytotoxic T cells in the anthroposophic group. Improvement in physical symptoms along with less anxiety in this group may have influenced the brain-immune axis resulting in lower frequency of CD8+ T cells, a feature associated with less aggressive cancer stages. To evaluate whether this observation is associated with good or bad prognosis, further detailed analyses of memory and naïve CD8+ T cells at tumor site and in blood circulation are essential.

Annexin A1 in blood mononuclear cells from patients with coronary artery disease: Its association with inflammatory status and glucocorticoid sensitivity

Annexin A1 (AnxA1) is a key player in resolution of inflammation and a mediator of glucocorticoid actions. In atherosclerotic tissue, increased expression of AnxA1 has been associated with protective plaque-stabilizing effects. Here, we investigated the expression of AnxA1 in peripheral blood mononuclear cells (PBMCs) from patients with coronary artery disease (CAD). Blood was collected from 57 patients with stable CAD (SCAD) and 41 healthy controls. We also included a minor group (n = 10) with acute coronary syndrome (ACS). AnxA1 mRNA was measured in PBMCs. Expression of AnxA1 protein (total and surface-bound) and glucocorticoid receptors (GR) were detected in PBMC subsets by flow cytometry. Also, salivary cortisol, interleukin(IL)-6 and IL-10 in plasma, and LPS-induced cytokine secretion from PBMCs, with or without dexamethasone, were assessed. AnxA1 mRNA was found to be slightly increased in PBMCs from SCAD patients compared with controls. However, protein expression of AnxA1 or GRs in PBMC subsets did not differ between SCAD patients and controls, despite SCAD patients showing a more proinflammatory cytokine profile ex vivo. Only surface expression of AnxA1 on monocytes correlated with dexamethasone-mediated suppression of cytokines. In ACS patients, a marked activation of AnxA1 was seen involving both gene expression and translocation of protein to cell surface probably reflecting a rapid glucocorticoid action modulating the acute inflammatory response in ACS. To conclude, surface expression of AnxA1 on monocytes may reflect the degree of glucocorticoid sensitivity. Speculatively, "normal" surface expression of AnxA1 indicates that anti-inflammatory capacity is impaired in SCAD patients.

Temporal biological variability in dendritic cells and regulatory T cells in peripheral blood of healthy adults

BACKGROUND

Studies evaluating circulating dendritic cells (DCs) and natural and induced regulatory T cells (nTregs, iTregs) are often obtained at a single time point and difficult to interpret without understanding their intrinsic day-to-day biologic variability.

METHODS

We investigated the day-to-day variability in quantifying DCs, nTregs (FoxP3(+)CD25(+)CD4(+)) and cytokine production by iTregs (granzyme B-GZB, Th1/2 cytokines following CD3 plus CD46 in vitro activation) from peripheral blood mononuclear cells (PBMCs) collected on three consecutive days in healthy adults. Intraclass correlation coefficients (ICCs) were used to evaluate intra-individual variability.

RESULTS

In 10 healthy adults, the %PBMCs of plasmacytoid (pDC) and myeloid (mDC1 and mDC2) were 0.27 ± 0.12, 0.22 ± 0.10, and 0.02 ± 0.02, with ICC 0.91, 0.90, and 0.17 respectively. Natural Tregs (3.27 ± 1.27% CD4(+) cells) had an ICC of 0.86. Inducible Tregs (GZB-positive, 35.3 ± 17.7% CD4(+) cells) had an ICC of 0.77. The ICCs for IL-10, TNF-α, IFN-γ, IL-4, and IL-5 production by iTregs were 0.49, 0.63, 0.68, 0.74, and 0.82, respectively. There were no significant changes in ICC (<0.1) after adjusting for age, gender and atopy except for IL-4. Substantial variability for iTregs was determined for the control condition (PBS with IL-2).

CONCLUSIONS

No meaningful day-to-day biologic variability was observed for the quantification of nTregs, pDC and mDC1 in normal adults; however, there was substantial variability in measuring mDC2 proportions and iTreg production of IL-10. These results suggest obtaining an average of several measurements over time to determine the most representative value of these biologic measures.

Neutrophil/Lymphocyte ratio is associated with non-calcified plaque burden in patients with coronary artery disease

Background

Elevations in soluble markers of inflammation and changes in leukocyte subset distribution are frequently reported in patients with coronary artery disease (CAD). Lately, the neutrophil/lymphocyte ratio has emerged as a potential marker of both CAD severity and cardiovascular prognosis.

Objectives

The aim of the study was to investigate whether neutrophil/lymphocyte ratio and other immune-inflammatory markers were related to plaque burden, as assessed by coronary computed tomography angiography (CCTA), in patients with CAD.

Methods

Twenty patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) and 30 patients with stable angina (SA) underwent CCTA at two occasions, immediately prior to coronary angiography and after three months. Atherosclerotic plaques were classified as calcified, mixed and non-calcified. Blood samples were drawn at both occasions. Leukocyte subsets were analyzed by white blood cell differential counts and flow cytometry. Levels of C-reactive protein (CRP) and interleukin(IL)-6 were measured in plasma. Blood analyses were also performed in 37 healthy controls.

Results

Plaque variables did not change over 3 months, total plaque burden being similar in NSTE-ACS and SA. However, non-calcified/total plaque ratio was higher in NSTE-ACS, 0.25(0.09–0.44) vs 0.11(0.00–0.25), p<0.05. At admission, levels of monocytes, neutrophils, neutrophil/lymphocyte ratios, CD4+ T cells, CRP and IL-6 were significantly elevated, while levels of NK cells were reduced, in both patient groups as compared to controls. After 3 months, levels of monocytes, neutrophils, neutrophil/lymphocyte ratios and CD4+ T cells remained elevated in patients. Neutrophil/lymphocyte ratios and neutrophil counts correlated significantly with numbers of non-calcified plaques and also with non-calcified/total plaque ratio (r = 0.403, p = 0.010 and r = 0.382, p = 0.024, respectively), but not with total plaque burden.

Conclusions

Among immune-inflammatory markers in NSTE-ACS and SA patients, neutrophil counts and neutrophil/lymphocyte ratios were significantly correlated with non-calcified plaques. Data suggest that these easily measured biomarkers reflect the burden of vulnerable plaques in CAD.

Exercise training, lymphocyte subsets and their cytokines production: experience of an Italian professional football team and their impact on allergy

BACKGROUND

In recent years, numerous articles have attempted to shed light on our understanding of the pathophysiological mechanisms of exercise-induced immunologic changes and their impact on allergy and asthma. It is known that lymphocyte subclasses, cytokines, and chemokines show modifications after exercise, but outcomes can be affected by the type of exercise as well as by its intensity and duration. Interesting data have been presented in many recent studies on mouse models, but few studies on humans have been performed to check the long-term effects of exercise over a whole championship season.

METHODS

This study evaluated lymphocyte subsets and their intracellular IL-2, IL-4, TNF-α, and IFN-γ production in professional football (soccer) players, at three stages of the season, to evaluate if alterations occur, particularly in relation to their allergic status.

RESULTS AND CONCLUSION

Despite significant mid-season alterations, no significant lymphocyte subclasses count modifications, except for NKs that were significantly higher, were observed at the end. IL-2 and IL-4 producing cells showed a significant decrease (P = 0.018 and P = 0.001, but in a steady fashion for IL-4), confirming the murine data about the potential beneficial effects of aerobic exercise for allergic asthma.

Exercise training, lymphocyte subsets and their cytokines production: experience of an Italian professional football team and their impact on allergy

BACKGROUND

In recent years, numerous articles have attempted to shed light on our understanding of the pathophysiological mechanisms of exercise-induced immunologic changes and their impact on allergy and asthma. It is known that lymphocyte subclasses, cytokines, and chemokines show modifications after exercise, but outcomes can be affected by the type of exercise as well as by its intensity and duration. Interesting data have been presented in many recent studies on mouse models, but few studies on humans have been performed to check the long-term effects of exercise over a whole championship season.

METHODS

This study evaluated lymphocyte subsets and their intracellular IL-2, IL-4, TNF-α, and IFN-γ production in professional football (soccer) players, at three stages of the season, to evaluate if alterations occur, particularly in relation to their allergic status.

RESULTS AND CONCLUSION

Despite significant mid-season alterations, no significant lymphocyte subclasses count modifications, except for NKs that were significantly higher, were observed at the end. IL-2 and IL-4 producing cells showed a significant decrease (P = 0.018 and P = 0.001, but in a steady fashion for IL-4), confirming the murine data about the potential beneficial effects of aerobic exercise for allergic asthma.

Natural killer (NK) cell deficit in coronary artery disease: no aberrations in phenotype but sustained reduction of NK cells is associated with low-grade inflammation

Although reduced natural killer (NK) cell levels have been reported consistently in patients with coronary artery disease (CAD), the clinical significance and persistence of this immune perturbation is not clarified. In this study we characterized the NK cell deficit further by determining (i) differentiation surface markers and cytokine profile of NK cell subsets and (ii) ability to reconstitute NK cell levels over time. Flow cytometry was used to analyse NK cell subsets and the intracellular cytokine profile in 31 patients with non-ST elevation myocardial infarction (non-STEMI), 34 patients with stable angina (SA) and 37 healthy controls. In blood collected prior to coronary angiography, the proportions of NK cells were reduced significantly in non-STEMI and SA patients compared with controls, whereas NK cell subset analyses or cytokine profile measurements did not reveal any differences across groups. During a 12-month follow-up, the proportions of NK cells increased, although not in all patients. Failure to reconstitute NK cell levels was associated with several components of metabolic syndrome. Moreover, interleukin (IL)-6 levels remained high in patients with sustained NK cell deficit, whereas a decline in IL-6 (P < 0·001) was seen in patients with a pronounced increase in NK cells. In conclusion, we found no evidence that reduction of NK cells in CAD patients was associated with aberrations in NK cell phenotype at any clinical stage of the disease. Conversely, failure to reconstitute NK cell levels was associated with a persistent low-grade inflammation, suggesting a protective role of NK cells in CAD.

Soluble Fas ligand is associated with natural killer cell dynamics in coronary artery disease

OBJECTIVE

Apoptosis of natural killer (NK) cells is increased in patients with coronary artery disease (CAD) and may explain why NK cell levels are altered in these patients. Soluble forms of Fas and Fas ligand (L) are considered as markers of apoptosis. Here, we investigated whether plasma levels of Fas and FasL were associated with NK cell apoptosis and NK cell levels in CAD patients.

METHODS

Fas and FasL in plasma were determined by ELISA in 2 cohorts of CAD patients; one longitudinal study measuring circulating NK cells and apoptotic NK cells by flow cytometry 1 day, 3 months and 12 months after a coronary event and one cross-sectional study measuring NK cell apoptosis ex vivo. Both studies included matched healthy controls. Fas and FasL were also determined in supernatants from NK cells undergoing cytokine-induced apoptosis in cell culture.

RESULTS

In the 12-month longitudinal study, plasma FasL increased by 15% (p<0.001) and NK cell levels by 31% (p<0.05) while plasma Fas did not change. Plasma FasL and NK cell levels were significantly related at 3 months and 12 months, r=0.40, p<0.01. Furthermore, plasma FasL, but not plasma Fas, correlated with NK cell apoptosis ex vivo in CAD patients, r=0.54, p<0.05. In vitro, cytokine-induced apoptosis of NK cells resulted in abundant release of FasL.

CONCLUSION

In CAD patients, FasL in plasma is associated with both apoptotic susceptibility of NK cells and dynamic changes in circulating NK cells. NK cells are also themselves a potential source of soluble FasL. Our findings link NK cell status to a soluble marker with possible atheroprotective effects thereby supporting a beneficial role of NK cells in CAD.

Biological variability of lymphocyte subsets of human adults' blood

BACKGROUND

Alterations in lymphocyte subpopulations are present in several immune diseases, and clinicians and researchers recognise the importance of investigating the distribution and changes in lymphocyte subsets over relatively long periods of time in order to evaluate the effectiveness of treatment and follow the course of disease. Yet further insight is required on the biological variability (BV) of lymphocyte subsets, which is crucial to the correct interpretation of longitudinal changes and provides essential information for setting desirable quality specifications and defining the usefulness of reference values.

METHODS

Four-colour-flow cytometry was used to investigate the BV of lymphocyte populations (LP) in the peripheral blood of 20 healthy adults recruited from our laboratory staff and followed for three months. The total lymphocyte count was measured, and the relative frequencies determined for T-cells (CD3+), T-helper cells (CD3+CD4+), cytolytic T-cells (CD3+CD8+), B-cells (CD3-CD19+), NK-cells (CD3-CD16+/56+), non-MHC restricted cytolytic T-cells (CD3+CD56+) and activated T-cells (CD3+HLA-DR+).

RESULTS AND CONCLUSIONS

Data on the components of BV were applied to set quality specifications for allowable precision, bias and total error. Analytical performances were established, and they were more than desirable for all the markers considered in our study. By comparing within-subject and between-subjects BV, we were able to define the uselessness of reference ranges in the evaluation of changes in CD serial results. Data on within-subject BV and analytical precision were thus used to determine the reference change values, in order to identify the significance of changes in serial results. The findings made in the present study provide further evidence of the relevance of BV in the evaluation of immunological markers of LP.

Persistent accumulation of interferon-γ-producing CD8+CD56+ T cells in blood from patients with coronary artery disease

OBJECTIVE

There is emerging evidence for CD8(+) T cell alterations in blood from patients with coronary artery disease (CAD). We examined whether the distribution and phenotype of CD8(+)CD56(+) T cells differed according to the clinical manifestation of CAD.

METHODS

Patients with acute coronary syndrome (ACS, n = 30), stable angina (SA, n = 34) and controls (n = 36) were included. Blood was collected before and up to 12 months after referral for coronary investigation. CD8(+)CD56(+) T cells were assessed by flow cytometry for expression of surface markers, apoptosis, and intracellular expression of cytokines.

RESULTS

The proportions of CD8(+)CD56(+) T cells were significantly higher in both ACS and SA patients compared with controls, and remained so after 3 and 12 months. This was independent of age, sex, systemic inflammation and cytomegalovirus seropositivity. CD8(+)CD56(+) T cells differed from CD8(+)CD56(-) T cells in terms of lower CD28 expression and fewer apoptotic cells. Both CD8(+) T cell subsets were positive for interferon (IFN)-γ and tumor necrosis factor, although IFN-γ was significantly more confined to the CD8(+)CD56(+) T cells.

CONCLUSION

The persistent accumulation of CD8(+)CD56(+) T cells in ACS and SA patients share several features with immunological aging. It also contributes to a larger IFN-γ(+) pool in blood, and may thereby hypothetically drive the atherosclerotic process in a less favorable direction.

Distribution of circulating natural killer cells and T lymphocytes in head and neck squamous cell carcinoma

OBJECTIVE

Natural killer (NK) cells are capable of eliminating malignantly transformed cells without prior sensitization. In contrast to NK-cells, T lymphocytes possess antitumourous activity that is restricted to major histocompatibility complex (MHC) recognition. The aim of this study was to determine the causes of the different distributions of these cell types in the peripheral blood of patients with head and neck squamous cell carcinomas (HNSCC).

METHODS

A cohort of 105 subjects was divided into three clinical groups: non-treated HNSCC patients, treated relapse-free HNSCC patients and healthy control subjects. Peripheral blood mononuclear cells (PBMC) were isolated from venous blood, subsets were depleted, flow cytometric counts were made and subsequently correlation analyses with clinical parameters were performed.

RESULTS

Treated relapse-free HNSCC patients have a significantly increased mean proportion of NK-cells in PBMC of 26.39% (p<0.001), whereas T lymphocytes and natural killer-T-(NKT) cells of treated patients have a significantly decreased mean proportion in PBMC of 55.15% (p<0.05) at least 12 months after treatment. This inverse redistribution of these two subsets is reflected in a significantly increased mean NK/T-ratio of 0.54 (p<0.05) in treated patients. The NK/T-ratio correlates with the systemic invasiveness of the type of therapy patients undergo and is highest after surgery with adjuvant radiochemotherapy (0.64, rs=0.334, p<0.01). This appears to be a post-therapeutic long-term effect in treated patients, as they had a mean relapse-free period until venous puncture of 47.9 months in our study. We also demonstrated age-dependent changes in the peripheral distribution of T- and NK-cells.

CONCLUSION

These findings reveal new aspects in understanding tumour biology and interactions with the cellular immune system which provide novel starting points for further research.

Elevated CD8 counts during HAART are associated with HIV virologic treatment failure

OBJECTIVE

To evaluate whether elevated CD8 counts are associated with increased risk of virologic treatment failure in HIV-infected individuals.

DESIGN

Retrospective cohort study.

METHODS

US Military HIV Natural History Study participants who initiated highly active antiretroviral therapy (HAART) in 1996-2008 had 6- and 12-month post-HAART HIV RNA <400 copies per milliliter, ≥ 2 subsequent HIV viral loads and a baseline CD8 count were eligible (n = 817). Baseline was 12 months after the start of HAART, virologic failure (VF) was defined as confirmed HIV RNA ≥ 400 copies per milliliter, and CD8 counts ≥ 1200 cells per cubic millimeter were considered elevated. Cox models were used to examine the effect of baseline and time-updated CD8 counts on VF.

RESULTS

There were 216 failures for a rate of 5.6 per 100 person-years [95% confidence interval (CI): 4.9 to 6.4]. Among those initiating HAART in 2000-2008, the participants with elevated baseline CD8 counts had significantly greater risk of VF compared with those with baseline CD8 counts ≤ 600 cells per cubic millimeter [hazard ratio (HR) = 2.68, 95% CI: 1.13 to 6.35]. The participants with elevated CD8 counts at >20% of previous 6-month follow-up visits had a greater risk of failure at the current visit than those who did not (HR = 1.53, 95% CI: 1.14 to 2.06). Those with CD8 counts that increased after the start of HAART had a greater risk of failure than those with CD8 counts that decreased or remained the same (HR = 1.59, 95% CI: 1.19 to 2.13).

CONCLUSIONS

Initial or serial elevated CD8 counts while on HAART or an increase in CD8 counts from HAART initiation may be early warnings for future treatment failure.

Seasonal variations in the onset and healing rates of venous leg ulcers

Objectives

As many vascular pathologies exhibit circannual fluctuation, the aim of this study was to assess the chronobiological features of venous ulcers.

Methods

Based on a retrospective survey of the case histories of 391 venous ulcer patients, the rates of ulcer onset and healing in each month were analysed statistically; a time series was constructed to evaluate the seasonality.

Results

There was a significantly higher frequency of ulcer onset during the warmer part of the year (April–October), and onset showed strong seasonality. Healing rates were also unequally and statistically significantly distributed throughout the year: ulcers that appeared or that were treated with specialized treatment in the winter or summer healed slower in comparison to ulcers that began in the spring or autumn.

Conclusions

Venous ulcers exhibit circannual fluctuations in their onset and healing rates. Hypothetically, in addition to exacerbation of chronic venous insufficiency, seasonal variations in immune system activity might potentially be responsible for this phenomenon.

Flow cytometric characterization of T lymphocyte subsets in the peripheral blood of Chinese rhesus macaques: normal range, age- and sex-related differences

Available data on the normal levels of white blood cell populations in healthy rhesus macaques (Macaca mulatta) originated and living in China is scanty. To obtain such data, blood samples from 150 Chinese rhesus macaques were collected and the normal range of white blood cells and their subsets were analyzed according to age and sex by flow cytometry. CBC data showed that the count of total white blood cells and lymphocytes decreased with age. Phenotypic analysis of CD4 and CD8 expression on CD3+ T lymphocytes showed that the percentage of CD4+ T cells (51.4+/-9.6%), CD4-CD8- T cells (8.5+/-4.1%) and the ratio of CD4+ T to CD8+ T cells (1.26+/-0.55) decreased with age; and the percentage of CD8+ T cells (42.0+/-9.7%), CD4+CD8+ T cells (1.3+/-0.9%) and CD3+ lymphocytes (55.3+/-13.3%) increased with age. However, no statistically significant difference was observed between the male and female groups in most parameters in these monkeys except for the percentage of CD4+CD8+ T cells. This study provided basic information about blood cell count and T lymphocyte subsets in Chinese rhesus macaques. It may be useful for comparative studies using Indian and Chinese rhesus macaques.