Lymphocyte immunophenotype reference ranges in healthy Indian adults: implications for management of HIV/AIDS in India

Assessment of immune cell profiles among post-menopausal women in the Women's Health Initiative using DNA methylation-based methods

BACKGROUND

Over the past decade, DNA methylation (DNAm)-based deconvolution methods that leverage cell-specific DNAm markers of immune cell types have been developed to provide accurate estimates of the proportions of leukocytes in peripheral blood. Immune cell phenotyping using DNAm markers, termed immunomethylomics or methylation cytometry, offers a solution for determining the body's immune cell landscape that does not require fresh blood and is scalable to large sample sizes. Despite significant advances in DNAm-based deconvolution, references at the population level are needed for clinical and research interpretation of these additional immune layers. Here we aim to provide some references for immune populations in a group of multi-ethnic post-menopausal American women.

RESULTS

We applied DNAm-based deconvolution to a large sample of post-menopausal women enrolled in the Women's Health Initiative (baseline, N = 58) or the ancillary Long Life Study (WHI-LLS, N = 1237) to determine the reference ranges of 58 immune parameters, including proportions and absolute counts for 19 leukocyte subsets and 20 derived cell ratios. Participants were 50-94 years old at the time of blood draw, and N = 898 (69.3%) self-identified as White. Using linear regression models, we observed significant associations between age at blood draw and absolute counts and proportions of naïve B, memory CD4+, naïve CD4+, naïve CD8+, memory CD8+ memory, neutrophils, and natural killer cells. We also assessed the same immune profiles in a subset of paired longitudinal samples collected 14-18 years apart across N = 52 participants. Our results demonstrate high inter-individual variability in rates of change of leukocyte subsets over this time. And, when conducting paired t tests to test the difference in counts and proportions between the baseline visit and LLS visit, there were significant changes in naïve B, memory CD4+, naïve CD4+, naïve CD8+, memory CD8+ cells and neutrophils, similar to the results seen when analyzing the association with age in the entire cohort.

CONCLUSIONS

Here, we show that derived cell counts largely reflect the immune profile associated with proportions and that these novel methods replicate the known immune profiles associated with age. Further, we demonstrate the value this methylation cytometry approach can add as a potential application in epidemiological studies.

A Critical Review on the Standardization and Quality Assessment of Nonfunctional Laboratory Tests Frequently Used to Identify Inborn Errors of Immunity

Inborn errors of immunity (IEI), which were previously termed primary immunodeficiency diseases, represent a large and growing heterogeneous group of diseases that are mostly monogenic. In addition to increased susceptibility to infections, other clinical phenotypes have recently been associated with IEI, such as autoimmune disorders, severe allergies, autoinflammatory disorders, benign lymphoproliferative diseases, and malignant manifestations. The IUIS 2019 classification comprises 430 distinct defects that, although rare individually, represent a group affecting a significant number of patients, with an overall prevalence of 1:1,200-2,000 in the general population. Early IEI diagnosis is critical for appropriate therapy and genetic counseling, however, this process is deeply dependent on accurate laboratory tests. Despite the striking importance of laboratory data for clinical immunologists, several IEI-relevant immunoassays still lack standardization, including standardized protocols, reference materials, and external quality assessment programs. Moreover, well-established reference values mostly remain to be determined, especially for early ages, when the most severe conditions manifest and diagnosis is critical for patient survival. In this article, we intend to approach the issue of standardization and quality control of the nonfunctional diagnostic tests used for IEI, focusing on those frequently utilized in clinical practice. Herein, we will focus on discussing the issues of nonfunctional immunoassays (flow cytometry, enzyme-linked immunosorbent assays, and turbidimetry/nephelometry, among others), as defined by the pure quantification of proteins or cell subsets without cell activation or cell culture-based methods.

Establishment of normative ranges of the healthy human immune system with comprehensive polychromatic flow cytometry profiling

Existing normative flow cytometry data have several limitations including small sample sizes, incompletely described study populations, variable flow cytometry methodology, and limited depth for defining lymphocyte subpopulations. To overcome these issues, we defined high-dimensional flow cytometry reference ranges for the healthy human immune system using Human Immunology Project Consortium methodologies after carefully screening 127 subjects deemed healthy through clinical and laboratory testing. We enrolled subjects in the following age cohorts: 18–29 years, 30–39, 40–49, and 50–66 and enrolled cohorts to ensure an even gender distribution and at least 30% non-Caucasians. From peripheral blood mononuclear cells, flow cytometry reference ranges were defined for >50 immune subsets including T-cell (activation, maturation, T follicular helper and regulatory T cell), B-cell, and innate cells. We also developed a web tool for visualization of the dataset and download of raw data. This dataset provides the immunology community with a resource to compare and extract data from rigorously characterized healthy subjects across age groups, gender and race.

Cytokine gene polymorphisms among North Indians: Implications for genetic predisposition?

Variations in the production and activity of cytokines influence the susceptibility and/or resistance to various infectious agents, autoimmune diseases, as well as the post-transplant engraftment/ rejection. Differences in the production of cytokines between individuals have been correlated to single nucleotide polymorphisms (SNPs) in the promoter, coding or non-coding regions of cytokine genes. The present study aimed at understanding distribution of cytokine gene variants among HIV seropositive subjects including HIV + TB+ subjects of Indian origin. Our findings indicate significant association of pro-inflammatory (IL2, IFN-γ, TNF-α) and anti-inflammatory cytokine gene variants (IL4, IL10) with the risk to acquire the HIV infection and development of AIDS related illness in Indian population. Since distribution of genetic polymorphisms varies significantly across different populations, different genotypes might exhibit different disease-modifying effects. An understanding of the immunogenetic factors or AIDS restriction genes is important not only for elucidating the mechanisms of disease pathogenesis but also for vaccine design and its application.

Vitamin C is taken up by human T cells via sodium-dependent vitamin C transporter 2 (SVCT2) and exerts inhibitory effects on the activation of these cells in vitro

Vitamin C is an essential micronutrient that affects immune responses. T cells are one of the main players in acquired immunity and have been reported to be influenced by in vivo vitamin C supplementation. Yet, the way by which T cells uptake vitamin C and what direct effects vitamin C exerts on the cells are not known. To elucidate, we isolated human peripheral blood T cells and analyzed the expression of sodium-dependent vitamin C transporters (SVCT). T cells were activated in vitro in the absence or presence of vitamin C, before or after activation. As results, human T cells expressed SVCT2, but not SVCT1, and the expression level increased following activation. Vitamin C added in the culture media generally did not affect T-cell behaviors following activation, such as proliferation, apoptosis, expression of CD25 and CD69, and interleukin 2 secretion, regardless whether it was added before or after activation. However, exceptionally, high concentration vitamin C, when it was added before activation, but not after activation, did exert toxic effects on cell activation with respect to the above-mentioned parameters. In conclusion, we showed the expression of SVCT2 in human T cells for the first time. Vitamin C exerted toxic effects, at least in vitro, when the concentration was high and when it was given before activation. These toxic effects are not thought to be via anti-oxidant effects of vitamin C.

Reference ranges of lymphocyte subsets balanced for age and gender from a population of healthy adults in Chongqing District of China

The enumeration of lymphocyte subsets plays an essential role in the monitoring of immunological disorders. Immunophenotyping values have been found to be influenced by race, age, gender, and environmental conditions. Therefore, it is important to establish reference ranges for healthy adults from the local population for clinical decision-making. The current study aimed to establish a normal reference range for peripheral blood lymphocyte subsets in healthy adults from the Chongqing District of China by using single-platform flow cytometry. Age- and gender-specific reference ranges were established in 268 healthy adult males and females between 21 and 60 years of age. The CD8+ cell counts decreased with age, CD4+ cell percentages and counts increased with age, and total T cell percentages were higher in the female population. Our results are similar to those reported from other parts of China but different from some results reported from other countries; this further stresses the need to establish local reference ranges by region. Our results will help in the management of patients with human immunodeficiency virus and other immunological disorders in Chongqing District. © 2015 International Clinical Cytometry Society.

Control lymphocyte subsets: can one country's values serve for another's?

Lymphocyte subsets can be affected by host and environmental factors, yet direct comparisons of their patterns across continents are lacking. This work compares proportions and counts of lymphocyte subsets between healthy children from Thailand, Malawi and the USA. We analyzed subsets of 1,399 healthy children aged between 0 and 15 years: 281 Thai, 397 Malawian and 721American children. Existing data for five subsets were available for all three cohorts (Total T, CD4+ T, CD8+ T, natural killer (NK) and B cells), with data for another six subsets from the Thai and American cohorts (naïve, memory and activated CD4+ and CD8+ T cells). Cellular patterns between cohorts differed mainly in children under two years. Compared to American children, Thai children had higher median numbers of total T cells, CD8+ T cells and NK cells while Malawian children under 18 months, on average, had more CD8+ T cells and B cells. Both Thai and Malawian children had lower median CD4+ T cell percentages and CD4/CD8 ratios than American children. Thai children had more memory and activated CD8+ T cells than American children. Approximately one-fifth of Thai and Malawian HIV-uninfected healthy children aged 0-3 years met WHO-defined CD4+ count criteria for immune-deficiency in HIV-infected children. Healthy children from Thailand, Malawi and the USA have differences in lymphocyte subsets that are likely to be due to differences in ethnicity, exposure to infectious diseases and environmental factors. These results indicate the need for country-specific reference ranges for diagnosis and management of immunologic disorders.

Reference ranges for lymphocyte subsets among healthy Hong Kong Chinese adults by single-platform flow cytometry

Race, age, sex, and environmental conditions have significant impacts on lymphocyte subset values. It is important to establish the local reference ranges from healthy and non-HIV-positive adults in the local population for clinical decision making. In this study, the reference ranges for lymphocyte subsets among Chinese adults were established by analysis by single-platform flow cytometry of the lymphocyte compositions of 273 healthy adult blood donors between 17 and 59 years of age. The 95% reference ranges for CD3(+) T cells, CD3(+) CD4(+) T helper cells, and CD3(+) CD8(+) T suppressor cells are 723 to 2,271 cells/μl, 396 to 1,309 cells/μl, and 224 to 1,014 cells/μl, respectively. The 95% reference ranges for CD19(+) B cells and CD56(+) NK cells are 118 to 645 cells/μl and 61 to 607 cells/μl, respectively. Significant gender and age differences in the lymphocyte subsets have been demonstrated. Our results have also shown that the T-lymphocyte compositions in Hong Kong Chinese were comparable to those of other Asian populations but were different from those of Caucasians.

One percent tenofovir applied topically to humanized BLT mice and used according to the CAPRISA 004 experimental design demonstrates partial protection from vaginal HIV infection, validating the BLT model for evaluation of new microbicide candidates

Recent iPrEx clinical trial results provided evidence that systemic preexposure prophylaxis (PrEP) with emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) can partially prevent rectal HIV transmission in humans. Similarly, we have previously demonstrated that systemic administration of the same FTC-TDF combination efficiently prevented rectal transmission in humanized bone marrow/liver/thymus (BLT) mice. The CAPRISA 004 trial recently demonstrated that topical application of the tenofovir could partially prevent vaginal HIV-1 transmission in humans. To further validate the usefulness of the BLT mouse model for testing HIV prevention strategies, we evaluated the topical administration of tenofovir as used in CAPRISA 004 to prevent vaginal HIV transmission in BLT mice. Our results demonstrate that vaginally administered 1% tenofovir significantly reduced HIV transmission in BLT mice (P = 0.002). Together with the results obtained after systemic antiretroviral PrEP, these topical inhibitor data serve to validate the use of humanized BLT mice to evaluate both systemic and topical inhibitors of HIV transmission. Based on these observations, we tested six additional microbicide candidates for their ability to prevent vaginal HIV transmission: a C-peptide fusion inhibitor (C52L), a membrane-disrupting amphipathic peptide inhibitor (C5A), a trimeric d-peptide fusion inhibitor (PIE12-Trimer), a combination of reverse transcriptase inhibitors (FTC-TDF), a thioester zinc finger inhibitor (TC247), and a small-molecule Rac inhibitor (NSC23766). No protection was seen with the Rac inhibitor NSC23766. The thioester compound TC247 offered partial protection. Significant protection was afforded by FTC-TDF, and complete protection was offered by three different peptide inhibitors tested. Our results demonstrate that these effective topical inhibitors have excellent potential to prevent vaginal HIV transmission in humans.

Factors associated with CD4 lymphocyte counts in HIV-negative Senegalese individuals

CD4+ lymphocytes are a primary target of the human immunodeficiency virus (HIV), and CD4 counts are one of the factors used to measure disease progression in HIV-positive individuals. CD4 counts vary in uninfected individuals and across populations due to a variety of demographic, environmental, immunological and genetic factors that probably persist throughout the course of HIV infection. This study sought to determine reference levels and identify factors that influence lymphocyte counts in 681 HIV-uninfected adults in Senegal, where residents are exposed to a variety of infectious diseases and other conditions that may affect CD4 counts. Lymphocyte counts were assessed in commercial sex workers, symptomatic men and women presenting to the University of Dakar infectious disease clinic for out-patient care and women seeking family planning services. CD4 and CD3 lymphocyte counts differed between the four study groups (P < 0.01). Men had the lowest mean CD4 count (711.6 cells/microl), while commercial sex workers had the highest levels (966.0 cells/microl). After adjustment for age and other behavioural and clinical factors, the difference in CD4 counts between the three groups of women did not remain. However, both gender and smoking were associated independently with CD4 counts, as men maintained lower mean CD4 counts (beta = -156.4 cells/microl, P < 0.01) and smokers had higher mean CD4 counts (beta = 124.0 cells/microl, P < 0.01) than non-smokers in multivariable analyses. This study is the first to explore factors that may influence CD4 levels in Senegal and to estimate baseline CD4 levels among HIV-negatives, information that may guide clinicians in interpreting CD4 counts.

Correlation of immune activation with HIV-1 RNA levels assayed by real-time RT-PCR in HIV-1 subtype C infected patients in Northern India

BACKGROUND

Assays with specificity and cost effectiveness are needed for the measurement of HIV-1 burden to monitor disease progression or response to anti-retroviral therapy (ART) in HIV-1 subtype C infected patients.

OBJECTIVES

The objective of this study was to develop and validate an affordable one step real-time RT-PCR assay with high specificity and sensitivity to measure plasma HIV-1 loads in HIV-1 subtype C infected patients.

RESULTS

We developed an RT-PCR assay to detect and quantitate plasma HIV-1 levels in HIV-1 subtype C infected patients. An inverse correlation between plasma viral loads (PVL) and CD4+ T-cell numbers was detected at all CDC stages. Significant correlations were found between CD8+ T-cell activation and PVL, as well as with the clinical and immunological status of the patients.

CONCLUSIONS

This RT-PCR assay provides a sensitive method to measure PVL in HIV-1 subtype C infected patients. Viral loads correlated with immune activation and can be used to monitor HIV care in India.

Lymphocyte numbers and subsets in the human blood. Do they mirror the situation in all organs?

Lymphocyte numbers in the blood are used to evaluate the immune status on a daily basis in medicine. Several studies have documented the normal ranges of lymphocytes and lymphocyte subsets in the peripheral blood. A variety of techniques and criteria have revealed clear differences between the lymphocyte subsets in childhood and adolescence. Race and gender are also variables for blood lymphocytes, and even environmental factors seem to influence the numbers of some lymphocyte populations. However, do all these variations in lymphocyte subsets in the peripheral blood mirror changes in the lymphocyte populations of the whole body, or is it just a result of different migratory habits of cells? The factors influencing the distribution of lymphocytes in the peripheral blood with regard to the different abilities of T and B cells to migrate to distinct lymphoid or non-lymphoid tissue are summarized. In addition it will be described how the removal of organs (e.g. thymus, spleen, liver) influences the distribution of lymphocytes in the blood. All these parameters should be considered not only in the clinical situation when the immune status of a patient is extrapolated from the lymphocyte numbers in the blood, but also when interpreting treatment effects in patients.

CDC staging based on absolute CD4 count and CD4 percentage in an HIV-1-infected Indian population: treatment implications

CD4+ T-cell levels are an important criterion for categorizing HIV-related clinical conditions according to the CDC classification system and are therefore important in the management of HIV by initiating antiretroviral therapy and prophylaxis for opportunistic infections due to HIV among HIV-infected individuals. However, it has been observed that the CD4 counts are affected by the geographical location, race, ethnic origin, age, gender and changes in total and differential leucocyte counts. In the light of this knowledge, we classified 600 HIV seropositive antiretroviral treatment (ART)-naïve Indian individuals belonging to different CDC groups A, B and C on the basis of CDC criteria of both CD4% and CD4 counts and receiver operating characteristic (ROC) curves were generated. Importantly, CDC staging on the basis of CD4% indicated significant clinical implications, requiring an early implementation of effective antiretroviral treatment regimen in HIV-infected individuals deprived of treatment when classified on the basis of CD4 counts.

Validity of existing CD4+ classification in north Indians, in predicting immune status

BACKGROUND

The CD4 lymphocyte count had ethnic variability as observed in many studies. In populations with CD4 counts inherently lower than in the West, the Center for Disease Control and Prevention (CDC) classification system of HIV-infected individuals may not be appropriate. As there is no such criterion currently available for ethnic north Indians HIV-patients, we undertook this study to assess the applicability of the western case definition in north Indian HIV patients.

METHODS

The CD4 counts of 40 normal and 376 HIV-infected north Indian adults attending to ID clinic, SS hospital, Varanasi were estimated by flowcytometry. The mean CD4 counts were estimated and compared between CDC groups A, B and C and controls. Receiver operator characteristic (ROC) curves were generated to determine the cut-off that correlated best with clinical staging for this population.

RESULTS

For CDC groups A, B and C, the mean CD4 counts/mul (upper limits of the 95% CI) were 380.3, 249.2 and 120.9, while the mean CD4 levels in healthy volunteers was 818.4.

CONCLUSION

The mean CD4 count among normal north Indians is significantly lower than that in the western population and parallels that of the Chinese. When categorized based on the Center for Disease Control and Prevention (CDC) classification system, the mean CD4 counts in HIV-infected individuals was lower. Categories of CD4 counts >280, 120-280 and < or =120 cells/microl correlate better with disease progression among HIV-infected individuals. A longitudinal study is required before guidelines for the India population can be devised.